UBC Theses and Dissertations

UBC Theses Logo

UBC Theses and Dissertations

Synthesis and photolysis of aromatic nitrate esters Csizmadia, Imre Gyula 1962

Your browser doesn't seem to have a PDF viewer, please download the PDF to view this item.

Item Metadata

Download

Media
831-UBC_1962_A1 C8 S8.pdf [ 8.46MB ]
Metadata
JSON: 831-1.0062250.json
JSON-LD: 831-1.0062250-ld.json
RDF/XML (Pretty): 831-1.0062250-rdf.xml
RDF/JSON: 831-1.0062250-rdf.json
Turtle: 831-1.0062250-turtle.txt
N-Triples: 831-1.0062250-rdf-ntriples.txt
Original Record: 831-1.0062250-source.json
Full Text
831-1.0062250-fulltext.txt
Citation
831-1.0062250.ris

Full Text

SYNTHESIS AND FHOTOLISIS OF AROMATIC NITRATE ESTERS  by BfflE G. CSIZMADIA Dipl. Chem. Eng., Polytechnical University of Budapest,  1956.  M.Sc, University of B r i t i s h Columbia,  1959•  A Thesis Submitted i n Partial Fulfilment of the Requirements for the Degree of DOCTOR OF PHILOSOPHY in the Department of CHEMISTRY  We accept this thesis as conforming to the required standard  THE UNIVERSITY OF BRITISH COLUMBIA SEPTEMBER, 1962.  \  In presenting  t h i s thesis i n p a r t i a l f u l f i l m e n t of  the r e q u i r e m e n t s f o r an advanced degree a t t h e U n i v e r s i t y  of  B r i t i s h Columbia, I agree t h a t the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e and for extensive  study.  I f u r t h e r agree t h a t p e r m i s s i o n  c o p y i n g o f t h i s t h e s i s f o r s c h o l a r l y p u r p o s e s may  g r a n t e d by the Head o f my Department o r by h i s  be  representatives.  I t i s understood t h a t copying or p u b l i c a t i o n of t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l not be a l l o w e d w i t h o u t my w r i t t e n p e r m i s s i o n .  Department o f The U n i v e r s i t y o f B r i t i s h Vancouver 8, Canada. Date  Columbia,  The U n i v e r s i t y  of B r i t i s h Columbia  FACULTY OF GRADUATE STUDIES  PROGRAMME OF THE FINAL ORAL EXAMINATION FOR' THE DEGREE OF DOCTOR OF PHILOSOPHY  of  IMRE G. CSIZMADIA D i p l . Chem. Eng. P o l y t e c h n i c a l U n i v e r s i t y of Budapest, 1956 M . S c , U n i v e r s i t y o f B r i t i s h Columbia, 1959 FRIDAY, SEPTEMBER 28, 1962, AT 2:30 P.M. IN ROOM 261, CHEMISTRY BUILDING PUBLICATION  1.  I.G. C s i z m a d i a and L„D« Hayward, Steric E f f e c t s i n N i t r a t e E s t e r s I . The S y n t h e s i s and S p e c t r a o f 1, 2-Acenaphthenediol D e r i v a t i v e s and the S t e r i c I n t e r a c t i o n o f Contiguous N i t r o x y Groups. T e t r a h e d r o n , submitted f o r p u b l i c a t i o n ,  COMMITTEE IN CHARGE Chairman: F„H„ J E, W.A. J,B L„D. S  0  BLOOR BRYCE FARMER HAYWARD  SOWARD J . P. c  A  0  D E„ C  KUTNEY  MCDOWELL  McGREER C.-REID  E x t e r n a l Examiner: P. de MAYO U n i v e r s i t y o f Western O n t a r i o  SYNTHESIS AND PHOTOLYSIS OF AROMATIC NITRATE ESTERS GRADUATE STUDIES  ABSTRACT N i t r a t e e s t e r s o f aromatic a l c o h o l s were s y n t h e s i z e d by e s t e r i f i c a t i o n which i n v o l v e d c o m p e t i t i o n between 0n i t r a t i o n and a r o m a t i c C - n i t r a t i o n . TLC a n a l y s i s gave a p a t t e r n o f a d s o r p t i o n a f f i n i t i e s f o r the n i t r o x y group and o t h e r s u b s t i t u e n t s c o n s i s t e n t w i t h t h e m o l e c u l a r conformations. The NMR frequency o f the CC-protons showed a l i n e a r c o r r e l a t i o n w i t h the a c c e p t e d group e l e c t r o n e g a t i v i t i e s o f the s u b s t i t u e n t s i n m o l e c u l e s w i t h r i g i d carbon s k e l e t o n s and gave a v a l u e o f 4.18 k c a l / m o l e f o r t h e n i t r o x y group. The symmetric and asymmetric IR s t r e t c h i n g f r e q u e n c i e s of n i t r o x y groups i n d i l u t e cyclohexane s o l u t i o n were s h i f t e d t o h i g h e r v a l u e s by s t e r i c i n t e r a c t i o n between contiguous groups when the C-QNQ2 bonds were c o n s t r a i n e d t o c o p l a n a r i t y . The UV s p e c t r a showed benzenoid, TC—*-TC*, and n-»ir* bands' and a s o l v e n t p e r t u r b a t i o n e f f e c t a s s i g n e d t o a s o l v e n t • —^-solute charge-transfer i n t e r a c t i o n . '  Field  o f Study;  Organic  Chemistry  Quantum Chemistry..................J.A.R. Coope S t a t i s t i c a l Mechanics ........ ......R.F. S n i d e r 3  C r y s t a l S t r u c t u r e s ..................K.B. Harvey Physical  Organic Chemistry  M o l e c u l a r Rearrangements...... Recent S y n t h e t i c Methods Chemistry  of Polysaccharides  L.W. Reeves R. . Stewart R.E. P i n c o c k A. Rosenthal .R.A. Bonnett D.E. McGreer G.G.S. Dutton  ;  The n i t r a t e e s t e r s r e a c t e d w i t h the s o l v e n t when i r r a d i a t e d i n s o l u t i o n i n the wavelength range o f the n — e x c i t a t i o n . Product a n a l y s i s i n d i c a t e d that C-C bond c l e a v a g e o c c u r r e d v i a i n t e r m e d i a t e a l k o x y l r a d i c a l s . Rate s t u d i e s showed the f o l l o w i n g order o f r e a c t i v i t y : benzyl n i t r a t e < d l - h y d r o b e n z o i n d i n i t r a t e <C mesoh y d r o b e n z o i n d i n i t r a t e , < t r a n s - 1 , 2-acenaphthenediol n i t r a t e <^ c i s - 1 , 2-acenaphthenediol d i n i t r a t e . The r a t e measurements and ESR s p e c t r a gave evidence o f i n t r a m o l e c u l a r energy t r a n s f e r from the naphthalene moiety to the n i t r o x y groups i n the 1, 2-acenaphthenediol d i n i t r a t e s a s s i g n e d as a s i n g l e t — ^ s i n g l e t t r a n s f e r . Calculations from the apparent f i r s t - o r d e r r a t e c o n s t a n t s and s p e c t r a showed t h a t b e n z y l n i t r a t e , and meso- and d l - h y d r o b e n z o i n d i n i t r a t e s p h o t o l y s e d w i t h a quantum y i e l d o f about 2 i n benzene s o l u t i o n . A s o l v e n t e f f e c t caused k g t 2 0 > ^EtOH > PhH. k  On the b a s i s o f product a n a l y s i s , r a t e measurements, e s t i m a t e d quantum y i e l d s and ESR s p e c t r a a mechanism f o r the n i t r a t e e s t e r p h o t o l y s i s was proposed.  Related Studies: Biochemistry  D i f f e r e n t i a l Equations.. Computer Programming Analogue Computers  M. Darrach J. Polglase S.H. Zbarsky . . . J . Abramowich H. Dempster E.V. Bohn  (ii) ABSTRACT  Nitrate esters of aromatic alcohols have been synthesized  success-  f u l l y by direct esterification which involved competition between ^-nitration andr aromatic C-nitration.  The physical properties of the f u l l y characterised  nitrate esters have been studied by TLC and by NMR, IR, and UV spectroscopy,, TLC results gave a consistent pattern of adsorption a f f i n i t i e s for the nitroxy group and other substituents and also revealed  stereochemical  features of the nitrate esters. The NMR frequency of the OC—protons i n substituted carbinoljte, R'R"CHOX, showed correlation with the accepted group electronegativities of X i f the system had a r i g i d carbon skeleton.  The correlation f a i l e d however  when free rotation was possible on the common bond i n substituted d i o l s . The correlation also showed the nitroxy group electronegativity to be higher (ca. 4.18 kcal/mole) than hitherto reported. The characteristic infrared frequencies measured i n dilute cyclohexane,solutions  of nitroxy groups were  of the nitrate esters and showed  shifts to higher frequencies due to steric interaction between contiguous nitrate ester groups when the C-ONC^ bonds were constrained to coplanarity. The UV spectra of the aromatic nitrate esters showed benzenoid, It—»fC  and n  —  - bands and a solvent perturbation effect which was  assigned to a solvent—*• solute charge—transfer  tenta  interaction similar to that  previously reported for aliphatic nitro compounds. Fhotolytic experiments revealed that nitrate esters underwent photochemical reaction when irradiated i n the wavelength range of the n—*-1t excitation.  Product analysis indicated that C-C bond cleavage occurred  (lli)  which was  explained  i n terms of intermediate  a l k o x y l r a d i c a l formation.  Rate studies of the p h o t o l y s i s showed the f o l l o w i n g order of r e a c t i v i t y ? Benzyl N i t r a t e <C" dl-Hydrobenzoin D i n i t r a t e  4.  Dinitrate, ^  cis-l,2-Acenaphthenediol  Dinitrate.  jbraij£-l2-Acenaphthenediol D i n i t r a t e ^ Both rate measurements and ESR  intramolecular  meso-Hydrobenzoin  spectra gave evidence of  extensive  energy t r a n s f e r from the naphthalene moiety to the n i t r o x y groups  i n the 1,2-acenaphthenediol d i n i t r a t e s which was singlet transfer.  assigned as a s i n g l e t  C a l c u l a t i o n s from the k i n e t i c data and  benzyl n i t r a t e , and meso—  spectra showed that  and dl—hydrobenzoin d i n i t r a t e s photolysed with a  quantum y i e l d of about 2 i n benzene s o l u t i o n .  A solvent e f f e c t caused the  f o l l o w i n g r a t e enhancement:  ^Et 0 2  >  ^tOH  >  k  PhH  On the basis of product a n a l y s i s , rate and quantum y i e l d measurements and ESR proposed.  spectra a mechanism f o r the n i t r a t e ester p h o t o l y s i s  was  (ma)  A D D E N D A Pages 63-66.  The 1,2-acenaphthenediol d i n i t r a t e s were f u l l y character-  ised "by the author m  a previous research (68). The nitrogen analyses  (Table XII) and IR spectra (Figure 9) of the crude by-products (£ B  ,  , C and C ) were examined i n an attempt to establish the trans^ c i s trans  occurrence of r i n g - n i t r a t i o n and complete characterisation was not undertaken. Pages 101 and 103.  The i d e n t i t i e s of substances E, E' and E'' given  on page 101 are not correct.  The bands at 2900 and 1726 cm~l (Figure 2k)  pointed to the presence of aldehyde groups m Pages 120 and 121.  conjugated bond systems.  The energy transfer process suggested i n paragraph 3  would only be probable i f the (undetermined) energy levels were related as shown m  Figure 30.  The observed spectra (68) implied t h i s would be  an " u p h i l l " energy t r a n s f e r .  This i s a r a r e l y observed phenomenon, but  cannot be e n t i r e l y excluded.  Very e f f i c i e n t u t i l i s a t i o n of n-*^.* energy  i n the photodecomposition might s h i f t the equilibrium toward t h i s form. A l t e r n a t i v e l y , and more probably, there may be t r a n s f e r to some state of lower energy than the  T T * state.  This might be a charge-transfer  state, from which d i r e c t decomposition i s possible. Page 142.  Other factors including the presence of the r e l a t i v e l y heavy  atoms 0 and N and the altered symmetry of the molecule could also be expected to reduce the l i f e t i m e of the t r i p l e t state s u f f i c i e n t l y t o make the ESR s i g n a l undetectable. Pages 152 and 153•  The i d e n t i t i e s of Fractions A, B, and C were not  s a t i s f a c t o r i l y established since the elementary analyses were either lacking or d i d not agree with the calculated values.  (XV  >  ACKNOWLEDGMENTS  I wish t o express my very sincere thanks and a p p r e c i a t i o n t o Dr. L. D. Hayward f o r h i s h e l p and encouragement throughout the course of the research and the p r e p a r a t i o n of t h i s t h e s i s . I wish a l s o t o express sincere g r a t i t u d e t o the Head of the Department, Dr. C. A. McDowell f o r h i s continuing i n t e r e s t i n the work and f o r making a v a i l a b l e the ESR f a c i l i t i e s of h i s l a b o r a t o r y . My thanks are a l s o due t o Dr. J . B. Parmer of t h i s Department f o r h e l p with the a n a l y s i s of the ESR spectra, t o Dr. D. H o l l i s of V a r i a n A s s o c i a t e s , Palo A l t o , who a t miy; request, k i n d l y recorded  the f i r s t ex-  p l o r a t o r y ESR spectrum of an i r r a d i a t e d n i t r a t e e s t e r , and t o the students and s t a f f of the Department ESR l a b o r a t o r y f o r t h e i r valuable t e c h n i c a l assistance. For h e l p f u l d i s c u s s i o n on t h e o r e t i c a l and spectroscopic  questions  I am indebted t o Dr. J * B l o o r of the B.C. Research C o u n c i l and t o D r s . D. McGreer and L. ¥ . Reeves of t h i s Department.  F o r mass-spectral  analysis  I wish t o thank Dr. D* C* F r o s t . F i n a l l y , I wish t o express my a p p r e c i a t i o n t o the National Research C o u n c i l of Canada f o r a studentship f o r the p e r i o d 1960-62.  TABLE OP CONTENTS TITLE PAGE  (1)  ABSTRACT  (n)  ACKNOWLEDGMENTS^....*....  (iv)  TABLE OP CONTENTS  (v)  LIST OP FIGURES  (vn)  LIST OF TABLES  W  GENERAL INTRODUCTION  1  HISTORICAL INTRODUCTION  4  The Chemistry of the Nitrate Esters I. II. III, IV. V.  5  (R ) XN0 Compounds Properties of the Nitrate Esters The Structure of Nitrate Esters Syntheses of Nitrate Esters Reactions of Nitrate Esters  6 13 15 16 20  A. Electrophi]ic Substitution on Oxygen (Sg„) B. Nucleophilic Substitution on Carbon ( S ^ / and Nitrogen (S ) C. Olefin (EQJQ) and Carbonyl (E _ ) Elimination Reactions .TT; D. Homolytic Decomposition of Nitrate Esters...........  23  1  2  C  26  Q  32 36  The Photochemistry of the Nitrate Esters and Related Compounds  ....•••••.»••••••..........  41  RESULTS AND DISCUSSION I. II. III. IV.  Synthesis of Aromatic Nitrate Esters Chromatography of Nitrate Esters Analysis of Aromatic Nitrate Esters Spectra of Aromatic Nitrate Esters A. Nuclear Magnetic Resonance: Spectra (NMR) B. Infrared Spectra (IR) C. Ultraviolet Spectra (UV)  58  •  59 67 75 76 76 81 84  (vi)  V.  P h o t o l y s i s of Aromatic N i t r a t e E s t e r s A. B. C. D. E.  P r e l i m i n a r y Experiments ............... I d e n t i f i c a t i o n of P h o t o l y s i s Products • K i n e t i c Study o f the P h o t o l y s i s .... .......... ESR Study of N i t r a t e E s t e r P h o t o l y s i s Summary of Proposed R e a c t i o n Mechanism  90 90 97 113 130 142  EXPERIMENTAL  146  I.  Materials  147  A. B. C. D.  147 148 148 153  Solvents * Reagents Reference Compounds Aromatic N i t r a t e E s t e r s . . . (i) (ii) (m)  II.  III.  IT. V.  Starting Materials Aromatic N i t r a t e E s t e r s v i a D i r e c t Nitration Aromatic N i t r a t e E s t e r s v i a Exchange Reactions  153 158 162  Analyses  165  A.  M e l t i n g P o i n t Determinations  165  B.  Elementary Analyses  165  Spectra  165  A. B. C. D.  165 165 166 166  U l t r a v i o l e t S p e c t r a (UV) I n f r a r e d S p e c t r a (IR) E l e c t r o n S p i n Resonance S p e c t r a (ESR) Nuclear Magnetic Resonance S p e c t r a (NMR)  Chromatography  167  Photolyses  169  A. B. C. D. REFERENCES  •  L i g h t Sources and Apparatus P r e l i m i n a r y Experiments K i n e t i c Experiments I s o l a t i o n and I d e n t i f i c a t i o n of P h o t o r e a c t i o n Products  169 174 177 179 185  (vn)  LIST OP FIGURES  1.  C a l c u l a t e d I o n i c Character  2.  The S t r u c t u r e of the Organic N i t r a t e Group  17  3.  Resonance S t r u c t u r e s of the N i t r o x y Group  17  4.  Modes of S c i s s i o n of the N i t r o x y Group  22  5.  A. B.  6.  A. B.  7. 8.  of X-NO2 Bonds  11  Energy L e v e l s of M o l e c u l a r ' O r b i t a l s and P o s s i b l e Electronic Transitions for N i t r i t e Esters  44  T y p i c a l E l e c t r o n i c Spectrum of a N i t i * i t e E s t e r ( 2 - b u t y l n i t r i t e i n ether (95) )  44  Energy L e v e l s of Molecular O r b i t a l s and P o s s i b l e Electronic Transitions f o r Nitrate Esters  44  T y p i c a l E l e c t r o n i c Spectrum of a N i t r a t e E s t e r ( 2 - b u t y l n i t r a t e i n ethanol (95))  44  C o r r e l a t i o n o f Z-ONO and X-N0 Bond Length i n ( R ) Compounds X  2  n  XN0  2  52  T h i n - l a y e r Chromatography of N i t r a t i o n Products from c i s and t r a n s - l 2 — A c e n a p h t h e n e d i o l s .  65  i E - S p e c t r a of c i s — and trans-1,2-Acenaphthenediol N i t r a t i o n Products  66  10.  Chromatographic P a t t e r n s of Representative N i t r a t e E s t e r s  72  11.  C o r r e l a t i o n o f foijj w i t h Group E l e c t r o n e g a t i v i t i e s i n (A) trans-1,2-jCyclohexane(B) B e n z y l - (C) t r a n s and (D) cis-1,2-Acenaphthenyl-Denvatives  78  f  9.  12.  T e n t a t i v e C o r r e l a t i o n of Tbc^ and Mechanism i n the R e a c t i o n of N i t r a t e E s t e r s w i t h P y r i d i n e a t 25  80  13.  UV Spectrum of i s o — A m y l n i t r a t e m Methanol  85  14.  Benzenoid A b s o r p t i o n of Benzyjj&lcohol (A) B e n z y l H i t r a t e (B) i n Hexane S o l u t i o n D i f f e r e n c e Spectrum of Benzyljtiitrate and Benzyl|&lcohol m v a r i o u s Solvents  15. 16. 17. 18.  ............  C o r r e l a t i o n o f the Frequency of Band I w i t h the Ionization Potential  86 88  Solvent 89  C o r r e l a t i o n o f the Frequency of Band I I w i t h the Solvent Ionization Potential  89  Chromatographic S e p a r a t i o n of P h o t o l y s i s Products of Nitrate Esters  92  (vm)  19.  20.  21. 22.  Chromatographic S e p a r a t i o n of P h o t o l y s i s Products of Nitrate Esters  93  Chromatographic S e p a r a t i o n of P h o t o l y s i s c/f Products of Nitrate Esters  96  Chromatographic Separations of Products from P h o t o l y s i s of meso-Hydrobenzom D i n i t r a t e i n Benzene S o l u t i o n ....  99  P h e n o l i c Products I s o l a t e d from P h o t o l y z e d i i n C^H^) me s o-Hydr obenzo i n D i n i t r a t e  100  I n f r a r e d S p e c t r a of meso-JIydrobenzoin D i n i t r a t e (A) Nitrobenzene (B) and P h o t o l y s i s Products of A(C and D)  102  S p e c t r a (IR) of 2 , 4 - D i n i t r o p h e n o l (A) and P h o t o l y s i s Products from meso-Hydrobenzom D i n i t r a t e ( E , E and E") .....•••«•»••»•.•».......•........•.•.••....••••...  103  I n f r a r e d S p e c t r a of 2,6-Dinitro-4-Phenylphenol (A) and P h o t o l y t i c Products from meso-Hydrobenzom D i n i t r a t e (F, K and N) •  104  26.  NMR  106  27.  P o s s i b l e Mechanism of P h o t o l y s i s of Dinitrate  23. 24.  1  25.  S p e c t r a of 1,2-Diphenyl ethane d e r i v a t i v e s ........ meso-Hydrobenzoin  112  28.  Primary Photochemical Reactions of N i t r a t e E s t e r s (NE).  115  29.  Rates of P h o t o r e a c t i o n s of (A) Benzyl N i t r a t e , (B) d l - and (C) mesD~Hydrobenzpin J)initraje£, (D) t r a n s - and 7E) cis-1,2-Acenaphthenediol D i n i t r a t e s i n Benzene S o l u t i o n a t 24.2°C  117  T r i p l e t - T r i p l e t Energy T r a n s f e r Between Benzophenone and Naphthalene and S i n g l e t - S i n g l e t Energy T r a n s f e r w i t h i n 1,2-Acenaphthenediol D i n i t r a t e s  121  Rates of P h o t o r e a c t i o n s of meso-Hydrobenzoin D i n i t r a t e (A) and Benzyl N i t r a t e (B) i n E t h a n o l and of mesoHydrobenzom D i n i t r a t e (C) i n E t h e r a t 34.2 C  123  Energy L e v e l Diagram f o r N i t r a t e E s t e r - S o l v e n t Complex Excitation  125  L i g h t Energy E m i t t e d by Source (A) and Absorbed by meso-Hydrobenzom D i n i t r a t e ^B) and Solvent Benzene (C) i n the P h o t o r e a c t i o n a t 24.2 C  127  Steady S t a t e ESR S p e c t r a of I r r a d i a t e d c i s - ( A ) and t r a n s (B) 1,2-Acenaphthenediol D i n i t r a t e s and meso-(C) and dl-Hydrobenzom D i n i t r a t e s i n Benzene.Solution.at.Room.. Temperature.............  131  30.  31.  32.  33.  34.  (ix)  35.  36.  ESR Signals of Irradiated trans-1,2-Acenaphthenediol Dinitrate Obtained I n i t i a l l y (A) and After Ten Days in the Dark (B and C)  132  ESR Spectrum of NOg (A) i n Solid Argon and (B) Generated from trans-1 2-Acenaphthenediol Dinitrate m EPA at 77°K.  134  ESR Spectra of Irradiated .trans-1,2-Acenaphthenediol Dinitrate (0.1 M) (/) and N0 (0.2 M) (B) i n Benzane Solution  136  ESR Spectrum and Components of Irradiated trans-1,2-Acenaphthenediol Dinitrate  138  Rates of Generation of Components of ESR Spectrum of Irradiated Nitrate Ester  140  f  37.  38. 39. 40.  ESR Spectrum of Acenaphthene It-•It  41.  Proposed Mechanism of Nitrate Ester Photolysis i n Solution  144  Infrared Spectra of Ethylcarbonates of 1,2-Diphenylethane Derivatives  157  Flow Sheet of Separation of Nitration Products from trans-1,2-Acenaphthenediol  159  Reported Power Output and Observed Spectral Distribution for G.E.-^H85- A3 Medium Pressure Mercury-Arc Lamp  170  Reported Power Output for G.E.-A-H6 High Pressure MercuryArc Lamp ...............  170  Light Energy Emitted by Han#!ovia 100 watt High Pressure Mercury Arc Lamp  171  47.  Photoreactor  173  48.  TLC of trans-1 2-Acenaphthenediol Dinitrate Photoiysed i n Benzene Solution  175  49.  ESR Tube  175  50.  Solid State Infrared Spectra of,trans-1,2-Acenaphthenediol Dinitrate and one of i t s Photolysis Products  176  TLC of trans—l»2-^Acenaphthenediol Dinitrate after Photolysis i n Benzene Solution  178  Spectrum of Acetaldehyde from Photolysis of mesoHydrobenzom Dinitrate i n Ethanol.  183  42. 43. 44.  45.  46.  51. 52.  Triplet State m  EPA  143  t  (x)  LIST OP TABLES  I.  Second I o n i z a t i o n P o t e n t i a l , E l e c t r o n A f f i n i t y and E l e c t r o n e g a t i v i t y of  II.  E s t i m a t e d I o n i c Character of X-N Bonds i n ( R ) XNOg .... 1  III. IV. V. VI.  15  R e a c t i o n Mechanisms  22  E l i m i n a t i o n Reactions w i t h N u c l e o p h i l i c Reagent OH i n 9Uf° Aqueous E t h a n o l S o l u t i o n Isotope E f f e c t s i n the R e a c t i o n of B e n z y l n i t r a t e w i t h Sodium Ethoxide i n Abeolute E t h a n o l a t 60.2  VIII. IX.  XI.  XII. XIII.  XIV. XV. XVI. XVII. XVIII. XIX.  9  Molecular Parameters of the ONO2 Group  VII.  X.  9  n  33 34  Log - Frequency F a c t o r s and A c t i v a t i o n E n e r g i e s f o r Thermal Decomposition of N i t r a t e E s t e r s  39  The E f f e c t of Deuterium S u b s t i t u t i o n on Burning Rates of N i t r a t e E s t e r s .  40  Strvdwral'-Prqarties of Nitrogen-Oxygen Compounds  50  if*'^*  51  T r a n s i t i o n s of ( R ^ X N O Compounds  Fundamental I n f r a r e d Frequencies (cm" ) of (R^^XNC^ Compounds  51  N i t r a t i o n Products from c i s - and trans-1,2Acenaphthenediqls  65  1  R e l a t i o n s h i p of R^ Values and S t r u c t u r e i n P o l y n i t r o x y Compounds  70  Chromatographic Constants f o r N i t r a t e E s t e r s ...........  73  Combustion Analyses of P o l y n i t r a t e s  75  Group E l e c t r o n e g a t i v i t i e s and T -values f o r Oj-Hydrogens a n N i t r a t e E s t e r s and R e l a t e d Compounds * I n f r a r e d Frequencies of N i t r o x y Groups from Condensed State S p e c t r a  82  I n f r a r e d Frequencies of N i t r n x y Groups from S o l u t i o n Spectra  83  Solvent E f f e c t s i n D i f f e r e n t i a l S p e c t r a of Benzyl N i t r a t e and Benzyl A l c o h o l ,  90  77  (xi)  XX. XXI.  Photolysis of Nitrate Esters i n Benzene Solutions: Preliminary Experiments  94  Photolysis of Nitrate Esters i n Oxygen-free Absolute Benzene Solutions  95  \  XXII. XXIII. XXIV. XXV.  XXVI. XXVII.  Apparent First-Order Rate Constants for the Photolysis of Aromatic Nitrate Esters at 24.2 C  119  Calculated Ratios of Charge-Transfer Equilibrium Constants for Benzyl Nitrate m Solution  125  Calculated Values of for a-Fhenyl Substituted Nitrate Esters i n Benzene and i n Ethanol and Ether Solutions ...  128  Calculated Quantum yields for the Photolysis of a-Phenyl Substituted Nitrate Esters i n Three Different Solvents at 24.2°C  129  Observed Components of ESR Spectra of Irradiated Nitrate Esters  138  Melting Points and NMR  Spectra of 2,4-Dimtrophenyl-  hydrazones XXVIII. XXLX. XXX.  XXXI. XXXII. XXXIII.  Melting Points and NMR  149 Spectra of Nitrophenols  Reduction Products of Benzil  151 154  Attempted Syntheses of Aromatic Nitrate Esters from Cyclic and Ethyl Carbonates  164  Adsorbents and Supporting Materials for Chromatography..  167=  Solvents for Chromatography  168  Spray Reagents for Chromatography  168  GENERAL INTRODUCTION  - 2 -  Synthetic photochemistry u t i l i z e s l i g h t energy to b r i n g about s p e c i f i c chemical r e a c t i o n s . C l a s s i c a l examples are the hydrogen c h l o r i d e synthesis i n the gas phase and the v i t a m i n There are, m  synthesis i n the l i q u i d phase.  a d d i t i o n , numerous other photosynthetic r e a c t i o n s which  may  be used f o r the p r e p a r a t i o n of a v a r i e t y of compounds i n e x c e l l e n t y i e l d s whose syntheses by conventional chemical techniques would involve lengthy and tedious routes from a v a i l a b l e s t a r t i n g m a t e r i a l s ( l ) . During the i r r a d i a t i o n of a chemical system p a r t i c l e s of matter s u f f e r " c o l l i s i o n s " with the photons of l i g h t and i n the a n n i h i l a t i o n of the photons the molecules absorb the energy of the l i g h t quanta (€»V»v <XJA  USUCLI  and go into ;bfee" e x c i t e d state (2).  The normal maximum l i f e t i m e of an  —8 e x c i t e d state i s of the order of 10  )  smjlett  —7 to 10  sec.  D e a c t i v a t i o n of an  e x c i t e d state by one or more of s e v e r a l processes must occur w i t h i n t h i s period.  I f the process i s p h y s i c a l the energy absorbed  i s e i t h e r degraded  to heat or the primary absorption process i s reversed and the energy i s r a d i a t e d as fluorescence or phosphorescence.  I f , however, the molecule  becomes unstable when e x c i t e d i t breaks up i n t o fragments almost taneously (10 ^  —  10  s e c ) , photochemical  instan-  r e a c t i o n s take place and  the d e a c t i v a t i o n >prooessecanjbecclassifa&d^asochenucal. In p\ photochemical  reactions the primary fragments of the  decomposition are f r e e r a d i c a l s .  Most of the f r e e r a d i c a l intermediates  possess very short l i f e t i m e s and t h e i r s t r u c t u r e and r e a c t i v i t y  determine  the f u r t h e r steps i n the r e a c t i o n s . The p r o p e r t i e s of the e l e c t r o n i c a l l y e x c i t e d molecule d i f f e r from those of the same molecule e x c i t e d molecule may  usually  i n the ground state and thus the  undergo r e a c t i o n s with chemical reagents to which  - 3 -  i t would be r e s i s t a n t i n the ground s t a t e .  Therefore d e t a i l e d study of the  nature of photochemical r e a c t i o n s gives information not only about the nature of the f r e e r a d i c a l s formed i n the primary r e a c t i o n but also f u r n i s h e s valuable information about the chemical bond, Photosynthetic processes occur d a i l y i n every green organism m  living  the presence of l i g h t and raw m a t e r i a l s . Much e f f o r t has been  d i r e c t e d toward achieving understanding of these processes which occur i n the green c h l o r o p l a s t s of p l a n t s (3).  Recently an I t a l i a n school reported  i n v e s t i g a t i o n s (4) (5) of the i n v i t r o photosynthesis of amino a c i d s based on the p h o t o l y s i s of n i t r a t e  (N0^~) and n i t r i t e  (NC^ ) ions i n aqueous -  s o l u t i o n s of r e l a t i v e l y simple organic molecules e.g. glucose.  Consequently  there i s a demand f o r a b e t t e r understanding of the p h o t o l y t i c processes of nitrogen-oxygen compounds from both t h e o r e t i c a l and p r a c t i c a l p o i n t s of view. This t h e s i s i s concerned with the synthesis and p h o t o l y s i s of a c e r t a i n type of aromatic n i t r a t e e s t e r s . was twofold.  The aim of t h i s research work  F i r s t l y i t was hoped that r a d i c a l s l i b e r a t e d by the p h o t o l y s i s  of the aromatic n i t r a t e e s t e r s i n s o l u t i o n might have l i f e t i m e s long that t h e i r c h a r a c t e r i s t i c p r o p e r t i e s could be s t u d i e d .  sufficiently  Secondly i t  was hoped that the fragmentation p a t t e r n of the n i t r o x y group during photodecomposition might be determined which i n t u r n would throw l i g h t on the chemical and p h y s i o l o g i c a l p r o p e r t i e s of the s e v e r a l c l a s s e s of organic compounds which c o n t a i n oxygen-nitrogen bonds.  HISTORICAL  INTRODUCTION  The  Chemistry of the N i t r a t e  Esters  - 6 -  I. The  (R ) XNCV, Compounds, n £ 1  group as a substituent plays a p a r t i c u l a r l y important  r o l e i n chemistry.  The compounds i n which i t occurs (II) may be considered  as d e r i v a t i v e s of hydrides  (I) i n which a hydrogen attached  to a particular  atom (X), has been s u b s t i t u t e d by NC^ ( l ) . (R ) XH n  *  1  ( R ) XNCL n 2  I where  (l)  1  —  II  = I, I I , I I I , ... .. represents  the type of the  substituents and n = 0 , 1 , 2 , or 3 represents Thus, most conveniently,  the number of the s u b s t i t u e n t s .  compound I I may be termed an X - n i t r o d e r i v a t i v e .  This c l a s s i f i c a t i o n may be extended i n p r i n c i p l e to the whole p e r i o d i c system.  As examples the a l k y l hydrides  and the corresponding X - n i t r o  d e r i v a t i v e s f o r the second period elements are as f o l l o w s : LiH  RVBH  RBeH  LiN0  2  RBeN0  2  R'R'BN0  2  R'RVCH  R'R"NH  R'R'V'CNC^  R'R"NN0  EH*  ROH 2  R0N0  2  FN0  2  I t i s i n t e r e s t i n g t o note t h a t a t the beginning of the p e r i o d NC" bears a negative 2  N0  2  charge while a t the end the p o s i t i v e charge i s on the  group and t h a t there are intermediate  X - N bond w i t h i n the p e r i o d . considered  d i s t r i b u t i o n s of charge over the  The formation  of the X - N bond may be  as a combination of f r e e r a d i c a l s which may proceed by one of  three d i f f e r e n t routes: (R ) X'+^N0 1  (R ) X 1  o  +  + :NC~  (2)  (R ) X- + -NCL > (R ) X:N0 (3) n 2 n 2 (R ) X.*+"'N0 • (R ) X ' + Not (4) n 2 'n 2 — Although one may d i s t i n g u i s h these three r e a c t i o n s i t should be 1  1  o  W  1  1  o  N  - 7 -  emphasized thai: 3. i  s  "the general case r e s u l t i n g i n a covalent bond*  bond formed, however, may s t i l l possess a c e r t a i n degree of i o n i c The  The  character.  extreme cases are 2^ and 4_. The  amount of i o n i c character i n a given bond may be estimated (6)  from Pauling*s equation (5) f o r the r e a c t i o n A« + -B  *-  A-B  Amount of i o n i c character = l - e ~ where  i- A  ,  4 V  "  r  D  (5)  )  if- i s the d i f f e r e n c e between the e l e c t r o n e g a t i v i t i e s of the  a  r a d i c a l s A« and B* expressed i n the u n i t s of Pauling's scale The  amount of i o n i c character of the X-N bonds m  (kcal/mole). ( R ) XN0„ n 4 1  compounds may be estimated i f one takes i n the f i r s t approximation  '/•^  as the e l e c t r o n e g a t i v i t y of X* rather than of ( R ) X « • The e l e c t r o n e g a t i v i t y 1  of the N0  2  r a d i c a l i n Mulliken's scale  ( e v / p a r t i c l e ) i s the sum of the  i o n i z a t i o n p o t e n t i a l and e l e c t r o n a f f m i t y Pauling's scale  of NC^ and i t s equivalent i n  (kcal/mole) may be c a l c u l a t e d  ji  ?  = 0.168 (  (7) from equation j5:  i - 1.23)  i&i ^  M  where the s u b s c r i p t s P and M r e f e r t o Pauling's and Mulliken*s  scales  respectively. D i f f i c u l t y a r i s e s however i n the s e l e c t i o n of the value of the i o n i z a t i o n p o t e n t i a l of n i t r o g e n  dioxide  among the several which have been  an a I acfron in reported so far«  Each value corresponds t o the i o n i z a t i o n of^a p a r t i c u l a r  molecular o r b i t a l  (8).  recently  The f i r s t i o n i z a t i o n p o t e n t i a l has been re-determined  (9) as 9*80 + 0.05 ev while the published second i o n i z a t i o n  p o t e n t i a l s range between 11 and 12.3 ev; thus the reported value of 11.62 ev  (10) may be accepted as reasonable.  n e g a t i v i t y of N0 has  2  In the c a l c u l a t i o n of the e l e c t r o -  the f i r s t i o n i z a t i o n p o t e n t i a l should be used since i t  been assigned as the i o n i z a t i o n of the unpaired e l e c t r o n .  F o r some  -  8  -  unknown reason, however, the second i o n i z a t i o n p o t e n t i a l provides more reasonable values f o r the estimated p a r t i a l i o n i c character of X-N bonds (Table I I ) . For example, the f i r s t i o n i z a t i o n p o t e n t i a l gives about 8CfS i o n i c character f o r the F-NO^  bond whereas the second i o n i z a t i o n p o t e n t i a l  gives the value of 6O9S which i s i n b e t t e r agreement with the chemical p r o p e r t i e s of the compound. Table I .  The s e l e c t e d constants f o r NO^ are given i n  - 9" -  Table I Second I o n i z a t i o n P o t e n t i a l , E l e c t r o n A f f i n i t y and E l e c t r o n e g a t i v i t y of NO.  Experimental (10) I E  I  *P  p  + E a  (ev)  -  (kcal/mole) The corresponding  of ^  (12)  -  (ev)  a  (11)  11.62  (ev)  p  Theoretical after zero adjustment  Theoretical  12.89  11.62  4.12  2.85  -  14.47  -  2.23  values i n Pauling's scale  (13) and the values  - /^NO^ together with the estimated i o n i c character of the X-N bonds are  given i n Table I I .  Table I I Estimated Ionic Character of X-N Bonds i n ( R ) XNO, 1  Atomic Number  * X  " ^N0 (kcal/mole)  2  (kcal/mole)  Ionic Character of X-N0 2  3  Li  0.55  -1.68  0.50  4  Be  1.10  -1.13  0.27  5  B  1,85  -0.38  0.04  6  C  2.50  +0.27  0.01  7  N  3.15  +0.92  0.19  8  0  3.60  +1.37  0.37  9  F  4.15  +1.92  0.60  From Reference (13).  -  10  -  I f P a u l i n g s t h e o r e t i c a l curve f o r i o n i c character 1  extended over the negative  side of the s c a l e , one may estimate the magni-  tude of the p o s i t i v e or negative the  charge e x i s t i n g on the n i t r o g e n atom i n  (R ) XNO, compounds as shown i n Figure  1.  1  The  (5_) i s  two extremes are s i n g u l a r cases i . e . there  i s only one l i t h i u m  n i t r i t e and only one n i t r y l f l u o r i d e , however as the middle of the p e r i o d i s approached the number of p o s s i b i l i t i e s are increased.  At the geometrical  mid-point the Cj-nitro d e r i v a t i v e s u s u a l l y c a l l e d " n i t r o compounds" have the smallest amount of i o n i c character thoroughly s t u d i e d N0 the  2  derivatives.  s u b s t i t u e n t s R', R", R " 1  virtually  i n the C-NO2 bond and are the most  Because of the p o s s i b l e v a r i a t i o n of  the number of p o s s i b l e C - n i t r o compounds i s  unlimited. On the l e f t hand side of the p e r i o d only L i N 0  which i s a simple inorganic compound.  2  i s known so f a r ,  The b e r y l l i u m and boron compounds  have not been reported as y e t but there seems to be no obvious reason why they should not e x i s t . I t might be p o s s i b l e that the known mixed a l k y l or a r y l b e r y l l i u m (14)  (15) and boron h a l i d e s  (16) (17) would undergo a m e t a t h e t i c a l  reaction  with s i l v e r n i t r i t e as i n 7 and 8_s R-BeHal + AgN0  ^R-Be-N0  2  6+  R'RMBHal + AgN0  2  + AgHal  5-  *• R R"Bf- N0 1  2  (7)  2  + AgHal  (8)  - 12 -  The NCv, may  i n AgNC^ would be a n u c l e o p h i l i c reagent so that the r e a c t i o n s  be considered as n u c l e o p h i l i c s u b s t i t u t i o n s on Be or B (18). These compounds c o n t a i n i n g elements from the l e f t side of the  p e r i o d i c system probably would c o n s t i t u t e "chemical mirror images" of t h e i r counterparts from the r i g h t hand s i d e .  In other words the s t a b i l i t y of the  above h y p o t h e t i c a l b e r y l l i u m and boron n i t r o compounds would be expected to depend on the s u c c e s s f u l c r e a t i o n of a p a r t i a l p o s i t i v e charge on the m e t a l l o i d element  ( e s p e c i a l l y i n the case of b e r y l l i u m ) and t h i s would be  a f u n c t i o n of the nature of the R  1,  groups.  Prom t h i s reasoning i t f o l l o w s  that groups with higher e l e c t r o n withdrawing power (such as a r y l or p e r f l u o r o a l k y l ) would tend to s t a b i l i z e these compounds.  Two  pieces of  i n d i r e c t evidence seem t o support t h i s i d e a .  ^J-NO,  III  F  3  C x  B  / N 0  FaC^NOg  2  5  _ ^ > 0  <U  <U  (Q)  IV  V  VI  F i r s t l y phenyl n i t r a t e  2  (VI) does not e x i s t (19) very l i k e l y  because the e l e c t r o n withdrawing phenyl group decreases the necessary negative charge of the oxygen atom and creates p o s i t i o n s with higher e l e c t r o n d e n s i t y i n the aromatic r i n g .  For t h i s very reason an a r y l group .probably  would maintain a s u f f i c i e n t p o s i t i v e charge on the corresponding b e r y l l i u m compound  (III), Secondly the e l e c t r o n withdrawing e f f e c t of the C F ^ g r o u p i s w e l l  demonstrated by the lowering of the b a s i c i t y of an amine i n which i t i s substituted. CF CH NH 3  2  2  The change of p l ^ from 3.25  illustrates this effect  (20).  f o r CH CH NH 3  2  2  t o 5.7 f o r  N - Nitrodimethylamme has an  N-N  - 13 -  bond with a c e r t a i n amount of i o n i c c h a r a c t e r : the methyl groups by perfluoromethyls  (CH\j)  2  ^  — ^  e  P l  a  c  i  n  S  would cause a decrease i n the i o n i c  character, t h a t i s $ the compound would be covalent because of the e l e c t r o n withdrawing e f f e c t of the CP^-substituents. amme (bp 17°) has been reported  The N-nitro b i s - t r i f l u o r o m e t h y l -  (21) and the very much lower b o i l i n g point  compared (20) t o that of N-nitrodimethylamine (b.p. 187°)  suggests t h a t t h i s  i s indeed the case and that the corresponding boron compound (IV) should a l s o be s u f f i c i e n t l y s t a b l e f o r i s o l a t i o n . On the r i g h t hand side of the p e r i o d PN0 r e l a t i v e l y s t a b l e , i n o r g a n i c compound.  2  i s a well-known,  The remaining two types,  N-nitro  and J)-nitro compounds, are s t a b l e although h i g h l y r e a c t i v e and are u s u a l l y c l a s s i f i e d as organic compounds even i f the r e s t of the molecule elements other t h a n carbon as i n Me.jSON0  2  and Et.jS0N0  2  contains  (22) or i n Me.jSi0N0  2  and M e S i ( 0 N 0 ) ( 2 3 ) , 2  2  2  Compounds bearing the 0-N0 group ( n i t r o x y or O-nitro group, l e s s 2  f r e q u e n t l y n i t r a t e group) are o c c a s i o n a l l y termed "JD-nitro" d e r i v a t i v e s but are more f r e q u e n t l y given the name " n i t r a t e e s t e r s " because of the common method of s y n t h e s i s from n i t r i c a c i d and the corresponding a l c h o l s .  A II.  P r o p e r t i e s of the N i t r a t e E s t e r s .  Nitrate esters  (VII) are important from the chemical,  and p h y s i o l o g i c a l points of view. the N0  2  In s y n t h e t i c organic  technical  chemistry (24)  group i s used ( e s p e c i a l l y i n the carbohydrate f i e l d ) f o r b l o c k i n g  f r e e hydroxyl  groups as n i t r a t e e s t e r s u n t i l manipulations may be c a r r i e d  out on other parts of the molecule. v e n i e n t l y removable by hydrogenolysis importance  The b l o c k i n g covalent n i t r a t e i s conor by other r e d u c t i o n s .  The t e c h n i c a l  (25) of the n i t r a t e e s t e r s i s based on t h e i r explosive  nature.  - 14  -  " N i t r o g l y c e r i n e " ( g l y c e r o l t r i n i t r a t e ) , ethylene  g l y c o l d i n i t r a t e and  " n i t r o c e l l u l o s e " ( c e l l u l o s e n i t r a t e ) are w e l l known explosives and q u a n t i t i e s are manufactured both f o r m i l i t a r y and medical a p p l i c a t i o n (26) therapy of hypertension The  large  i n d u s t r i a l purposes.  The  (27) of n i t r a t e e s t e r s as s u c c e s s f u l drugs i n the and angina i s of long standing and great  symptoms of angina are "dramatic and t e r r o r i z i n g p a i n i n the  importance. chest  r a d i a t i n g from the r e g i o n of the heart to the l e f t shoulder and down the arm. i t may  I t may  l a s t f o r a p e r i o d of s e v e r a l seconds terminating  r e t u r n r e p e t i t i o u s l y over a period of s e v e r a l decades"  i n death or (27).  N i t r a t e e s t e r s r e l i e v e these attacks extremely r a p i d l y although the mechanism of t h e i r a c t i o n i s not known.  Immunity to a given n i t r a t e  compound i s b u i l t up over a period of time and new  ones must be  prescribed  frequently. In s p i t e of the importance of n i t r a t e esters our knowledge about t h e i r p h y s i c a l and  chemical behaviour i s s t i l l  that of other f a m i l i e s of organic compounds. that t h e i r chemical r e a c t i o n s are numerous and  l i m i t e d i n comparison to This may  be due  t o the  fact  complex and mechanisms vary  not only with reagent, r e a c t i o n conditions and s u b s t i t u e n t groups,  but are a l s o m u l t i p l i e d w i t h i n the n i t r o x y group i t s e l f .  This means i n  - 15  -  p r a c t i c e t h a t i n c o n t r a s t to the chemistry of other f u n c t i o n a l groups i n a p a r t i c u l a r set of r e a c t i o n conditions one cannot at present p r e d i c t with confidence how  a new  r e a c t i o n i s to be  n i t r a t e e s t e r w i l l behave, t h a t i s , what type of  expected*  III.  The Structure of N i t r a t e E s t e r s .  The s t r u c t u r e of the n i t r o x y group (Figure 2) i s more or l e s s accepted as planar (28) (29) (30) i n s p i t e of some evidence f o r a pyramidal arrangement (31)«  This planar arrangement i s considered to be g e n e r a l ,  although the e l e c t r o n d i f f r a c t i o n (28) evidence was  obtained from only two  pentaerythritol tetranitrate  (30) and X-ray c r y s t a l l o g r a p h i c  simple molecules, methyl n i t r a t e  (29)  and  (Table I I I ) . Raman and i n f r a r e d s p e c t r a agree  f o r the s t r u c t u r e shown i n Figure 2 and NMR  i n d i c a t e s only two types of oxygen  17 atoms i n the r a t i o 1:2  in  0 labelled ethyl nitrate  (32).  Table I I I Molecular Parameters of the 0N0-  Group.  References Location  1.44  01 N  - IT -  °2,3  (28)  (31)  1.37 1.22  (29)  1  1.43  I  1.37  1  i I  1.36  I  1.36  £  1.26  £  1.272  ZCOjN  109° 28»  105 t  5°  X02N03  131 t  125°  16'  5  °  i  123°  This geometrical arrangement seems to be general f o r (R ) XNO  com-  pounds and may be considered as a f u n c t i o n of the NO,, group.* ~*) There are 4% e l e c t r o n s i n the group -NO- and thus i t does not f i t H u c k e l s 4n-2 r u l e . However i t i s planar and t h e r e f o r e s i m i l a r to other 4 l t e l e c t r o n systems (33) such as trimethylenemethane. 1  - 16 -  I t was proposed by Chedxn (34) from Raman spectra and was  con-  firmed by Booth and L l e w e l l y n (29) by X-ray a n a l y s i s t h a t the carbon atom l i e s i n a plane perpendicular to t h a t of the ONO^  group.  A set of resonance  s t r u c t u r e s f o r the group was suggested (19) s i m i l a r to those of the C - n i t r o group (Figure 3 ) .  IV.  Syntheses of N i t r a t e E s t e r s ,  Among the s e v e r a l p o s s i b l e s y n t h e t i c methods there are three most f r e q u e n t l y used f o r the preparation of n i t r a t e e s t e r s : (I)  The metathesis of organic halides with s i l v e r n i t r a t e i n  organic solvents SBr + AgN0 (ii) silver nitrate  *  3  2  + AgBr  (9)  The double decomposition of chloroformate e s t e r s with (Boschan*s method) R0C0C1 + AgN0  (iii)  R0N0  3  9- R0N0 + AgCl + C 0 2  ^  2  The d i r e c t e s t e r i f i c a t i o n ( O - n i t r a t i o n ) of the  corresponding a l c o h o l ROH + NO^I  •>• RON0 + HT  (ll)  2  Method ( l ) i s a favoured technique because the corresponding halogen compounds are r e a d i l y a v a i l a b l e  (35) i n many cases and the by-product s i l v e r  can be Separated e a s i l y *  bromide  The r e a c t i o n may be c a r r i e d out i n e i t h e r  homogeneous ( i n g l a c i a l a c e t i c a c i d or a c e t o n i t r i l e ) or i n heterogeneous ( i n ether, benzene, nitrobenzene or nitromethane) medium.  In the case of  synthesis of d i n i t r a t e s , d i f f i c u l t i e s a r i s e i n the exchange of the second v i c i n a l halogen atom which was  i n d i c a t e d c l e a r l y by F i s h b e i n (36) i n a  study of the r e a c t i o n of racemic- and meso-dibromobutane (VIII) w i t h s i l v e r  - 1 7 -  F I G U R E 3.  Resonance S t r u c t u r e s  of the N i t r o x y  Group  - 18  -  nitrate in acetonitnle. The r e a c t i o n occurred  i n a stepwise manner and the exchange of  the f i r s t bromine atom f o r n i t r o x y group was of the second one.  considerably  f a s t e r than that  Furthermore the f i r s t step proceeded with r e t e n t i o n of  c o n f i g u r a t i o n and the second with i n v e r s i o n .  The  f i r s t step was  explained  by a push-pull mechanism where "the neighbouring bromine atom p a r t i c i p a t e s i n a back side i n t e r n a l d i s p l a c i n g a c t i o n while the C-Br  bond of the  carbon  undergoing s u b s t i t u t i o n i s being weakened by an e l e c t r o p h i l i c a t t a c k halogen by s i l v e r "  (IX)  (12).  The  on  c y c l i c bromonium i o n (X) i s attacked  by the n i t r a t e i o n and with o v e r a l l r e t e n t i o n of c o n f i g u r a t i o n produces threo-2-bromo-3-nitroxy butane (XI)  (13). Since the n i t r a t e e s t e r group  does not p a r t i c i p a t e i n the e l i m i n a t i o n of the second bromine atom v i a a c y c l i c e s t e r t h e r e f o r e the next step proceeds by simple S^2 mechanism with p r a c t i c a l l y complete i n v e r s i o n of c o n f i g u r a t i o n Method ( i i ) was  introduced  (14).  f i r s t by Boschan (32) m  1959»  This  technique has the advantage that i t "does not involve rupture of the bond on the carbon atom adjacent to the n i t r a t e e s t e r group" therefore the n i t r a t e e s t e r obtained r e t a i n s the c o n f i g u r a t i o n of the parent a l c o h o l . a c t i o n i s considered  t o proceed v i a an intermediate  decomposes to the f i n a l product (l_5). Further i s now  i n progress The  The  re-  which r e a d i l y  development of t h i s r e a c t i o n  (38),  chloroformate s t a r t i n g m a t e r i a l i s u s u a l l y prepared from the  corresponding a l c o h o l and phosgene. prepared where the geometrical  For t h i s reason d i n i t r a t e s may  not  be  l o c a t i o n of the two hydroxyl groups favors  the formation of cyOlic carbonates.  -  Br i  H I  19  • Br:-) i ~>  Ag NO3  •CH-  NO-  I  Br  VIM  H  I  f-UC-C-  HUC—C—C—CHT H  -  (dl)  Ag  IX  Br / \ C — C l I H H  H C 3  CH-  NO3  +  AgBr  (12)  CH. /  ,C — B r  Br H,C  cr \CHNO; N  X  C  ?3  B  • V  C  H  r  (13)  3  2  CK, ^ H N 0 ^ / 3  0  O NO-  2  C  + Br  C -+H  \  2  / H  XI  NO:  0 NO  H /  ° 2  N  \H  O  XI  ° 2  N  XII  \  O  H  (14)  ,  XIII O 11  JZH-O CI  AgNQ  .c.  <1>  >H-O0  3  R  2  .  AgC I  •O- +  N0 Y 2  + /N O ; R-O: H  Co  / \  CH-0  + CO,  (15)  N-O /' " O  *  /io R—O:  2  + HY  (16)  - 20 -  Method ( i i i ) i s the most widely used to synthesize organic nitrate esters*  The reacting species i s N0  2  as i n aromatic nitration  (C-nitration) "where the attack by the substituting agent is on the unsaturation electrons, i . e . conjugated carbon 2p electrons.  Since non-  bonding electrons o f nitrogen and oxygen oan participate deeply i n such conjugation we should expect them to share many properties with the unsaturation 2p electrons of carbon including general vulnerability to electrophilio substituting agents" (39). Since the mechanism (16) i s closely related to that of C_-nitration the originally suggested (40) :  O-nitration term i s retained (41). There are a number of reagents which possess the structure NOg I " required for O-nitration and consequently a great diversity of preparative procedures. 0°C  The reaction i s usually carried out at or below  with one of the following reagents  (c)  HN0 /H S0 f  (g)  gaseous ^0,.}  3  2  (d) HN0 /Ac 0)  4  3  2  (h) NOgCl  (with or without catalyst).  (a)  HNO^f  (b) HNOj/HOClj|  (e) HNO^AOjO + AcOHj  (f) N ^ / f c C C ! ^  (with or without catalyst) j  ( i ) NOgP  These and other special synthetic routes  were extensively reviewed recently (27) (24) (42), A more detailed examination of the various nitration mechanisms i s made i n the ohapter on "Results and Discussion."  V.  Reactions of Nitrate Esters.  Since the reactions of organic nitrates depend on the structure of the nitrate ester as well as on the reagent and reaction conditions and often two or more types of reaction take place simultaneously only a few mechanistic  studies have so far been reported (43). It has been  pointed out recently (44) that a l l of the chemical transformations on  - 21 -  record may be considered as i n v o l v i n g one or more of f i v e p o s s i b l e modes of  s c i s s i o n of the e s t e r group.  Reactions which cause such bond cleavages  range from s o l v o l y s i s and h y d r o l y s i s through c a t a l y t i c hydrogenolysis t o photochemical decomposition and e x p l o s i o n s . The f i r s t three of the f i v e modes of s c i s s i o n (Figure 4) are h e t e r o l y t i c while the l a s t two are claimed t o be homolytic.  In other  words a l l r e a c t i o n s which proceed v i a an i o n i c mechanism seem t o cause bond cleavage i n the n i t r a t e moiety by one of modes 1, 2 or 3, while r e a c t i o n s o c c u r r i n g by f r e e r a d i c a l mechanism seem to involve mode 4 or 5. The f i r s t f o u r modes are w e l l e s t a b l i s h e d , while mode 5 i s t e n t a t i v e as yet  and i s based on i n d i r e c t evidence. Reagents causing i o n i c decomposition  (modes 1, 2 and 3) may be  e i t h e r e l e c t r o p h i l i c or n u c l e o p h i l i c and the r e a c t i o n s which occur may be s u b s t i t u t i o n s or e l i m i n a t i o n s .  The s u b s t i t u t i o n may be e l e c t r o p h i l i c (Sg)  or n u c l e o p h i l i c (S^.) according t o the nature of the reagent.  The e l i m i n a t i o n  r e a c t i o n s may be c l a s s i f i e d as carbonyl e l i m i n a t i o n ( E ) and o l e f i n i c pn  e l i m i n a t i o n (E„ _) depending are the f i n a l products (43).  on whether carbonyl or o l e f i n i c compounds Ionic r e a c t i o n s of the above types are  summarized i n Table IV. It i s i n t e r e s t i n g t o note that e l e c t r o p h i l i c reagents i n subs t i t u t i o n ( A, which may be charged e.g. H  +  or uncharged  e.g. Lewis a c i d s )  always a t t a c k the e l e c t r o n r i c h oxygen atom while n u c l e o p h i l i c reagents s u b s t i t u t i o n ( B; , which may be charged e.g. H0~ or E'tO  m  or uncharged e.g.  p y r i d i n e ) always a t t a c k the carbon neighbouring t o the NO^ or the n i t r o g e n of the n i t r o x y group which i n d i c a t e s that they must be more e l e c t r o n d e f i c i e n t than oxygen.  - 22 -  1  FIGURE  Modes  4  TABLE  1  O  A O  of Scission  IV  Electrophilic substitution  2  3  of the Nitroxy  Reaction  on  4  5 ?  Group  Mechanisms  Reaction Mechanisms  oxygen-.  M o d e of Scission  O  ~^\  Y  +  A  :C> •• R  N  ° 2  R  X  2  Nucleophilic  substitution  B:^* C:-ON0 >  3  Nucleophilic O  on  carbon:  B ; C  2  substitution  +  S  NO3  N C  on nitrogen:  O  v  ./—XN  B:N0 +  ^  B  2  R O  b  N  J  N  OR 4  ^-Hydrogen  B:  5  elimination  + H - C — C - O N C ^  oc-Hydrogen B: +  —- B:H*+  > C = C <  + NO3  E  C  =  C  1  elimination:  H - C —ON0  2  *  B:H*+  > C = 0  +  NO^  ^-Q=0  ^  -  A.  23  -  E l e c t r o p h i l i c S u b s t i t u t i o n on Oxygen (S^Q  )  E l e c t r o p h i l i c s u b s t i t u t i o n by proton (protonation) esters may  be considered  as the reverse  of n i t r a t e  r e a c t i o n o f _ 0 - n i t r a t i o n (17)*  The  r e a c t i o n occurs when a n i t r a t e ester i s d i s s o l v e d i n concentrated s u l f u r i c a c i d and the e q u i l i b r i u m i s very l i k e l y s h i f t e d f a r to the r i g h t (the a l c o h o l may  r e a c t f u r t h e r with the concentrated acid) since the  n i t r a t e ester may  not be recovered by a d d i t i o n of water.  u l t r a v i o l e t spectroscopy i n d i c a t e d the presence of NO* the o r i g i n a l e s t e r i n the aqueous s o l u t i o n  Furthermore  and the absence of  (42).  Because of t h i s phenomenon n i t r a t e esters may n i t r a t i n g agents ( 4 5 ) which i s an obvious extension  be used as  of the p r i n c i p l e of  n i t r a t i o n by NOgY since the more f r e q u e n t l y used n i t r i c a c i d may considered  as the zero member of the n i t r a t e e s t e r f a m i l y *  e x h i b i t mild n i t r a t i n g a c t i v i t y through s e l f i o n i z a t i o n . compounds are the n i t r a t e esters of cyanohydrins (XIV, XV, be used-for n i t r a t i o n of s e n s i t i v e compounds as was  be  I t i s worthy  of mention that c e r t a i n n i t r a t e esters with high m o b i l i t y of NOg  a review by Topchiev  original  can  Among these XVI)  which can  discussed r e c e n t l y  m  (46).  N i t r a t e esters a l s o undergo e l e c t r o p h i l i c s u b s t i t u t i o n on oxygen ) by other agents (18)«  A number of Lewis acids may  n i t r a t i o n c a t a l y s t with n i t r a t e e s t e r s .  be used as e f f e c t i v e  Thus benzene and toluene are  n i t r a t e d by e t h y l n i t r a t e i n the presence of aluminium c h l o r i d e J u s t as protonation  (47).  or other e l e c t r o p h i l i c s u b s t i t u t i o n occurred  on the oxygen atom of a n i t r a t e e s t e r i t should a l s o occur on the element (X) of every (R ) XML  compound i n which the element X possesses the  1  JX  £  necessary e l e c t r o n d e n s i t y .  In other words t h i s should be true f o r  - 24 -  R—Q  •°;  NOV  H  H  R—O'  NO.  (17)  NO,  3 \  /  C  C  H  3  C OgNO  \;N  0 NO 2  XIV  CN  O NO' C N X  2  XV  XVI  AICIR  0^+  AICI  R-o(  3  ^  N0  2  +  NOo  (R') X — N 0 * H N  2  RO \ CI  —  (R') XH N  •  NO*  /  Al  CI / \ CI  (18)  (19)  - 25 -  elements other than oxygen from the r i g h t hand side of the p e r i o d (N, 0, P ) . Consequently  the o r i g i n a l l y introduced S^  ( e l e c t r o p h i l i c s u b s t i t u t i o n on  oxygen) i s a s p e c i a l form of £L^ ( e l e c t r o p h i l i c s u b s t i t u t i o n on element X, i.e.s  E  g N  E  5  g Q  j  E p)  (19). Since the NO* formed i n t h i s r e a c t i o n i s the  g  n i t r a t i n g species i n every n i t r a t i o n t h e r e f o r e the a v a i l a b i l i t y of N0 determines  +  the n i t r a t i n g power of (R ) XN0~ or more p r e c i s e l y that of the 1  corresponding conjugate a c i d , (R ) X"*^^^ n H 1  I t has been known since 1905 t h a t n i t r y l f l u o r i d e (FNO,,) i s a powerful n i t r a t i n g agent  (48) (49). This f a c t was confirmed i n a more  recent p u b l i c a t i o n (50) and the e f f i c i e n c y of n i t r y l f l u o r i d e as an _0-nitrating agent was compared (51) with t h a t of n i t r y l c h l o r i d e (CINO^) (52).  I t was pointed out that " g e n e r a l l y there i s a greater y i e l d of  n i t r a t e d m a t e r i a l with n i t r y l f l u o r i d e than with the c h l o r i d e , even when the l a t t e r i s used with a c a t a l y s t .  This suggests t h a t n i t r y l f l u o r i d e  stands higher than n i t r y l c h l o r i d e i n the s e r i e s of n i t r a t i n g agents of the type XN0  2  i n which the n i t r a t i n g power increases with the e l e c t r o n  accepting q u a l i t y of X." ( 5 l ) , On t h i s b a s i s one may assemble a p r e l i m i n a r y s e r i e s of n i t r a t i n g agents from the e l e c t r o n e g a t i v i t y estimations i n Figure 1 as shown i n equation 2 0  0  R C-N0 3  2  -<  R N-N0 2  2  R0-N0  2  <T  F-N0  2  .C1-N0  (20)  2  E v i d e n t l y each member of t h i s s e r i e s except FN0  2  and C1N0  2  represents a  c l a s s of compounds and the a c t u a l n i t r a t i n g power l a r g e l y depends on the chemical nature of R.  Consequently f o r those members of the s e r i e s there  are s u b d i v i s i o n s which may f i l l  the gap between two neighbouring elements  \ \ - 26 -  or they may  evert, overlap each other.  We  \  may  consider  the  series  previously  compiled by G i l l e s p i e and M i l l e n (31) as a p o r t i o n of the s u b d i v i s i o n f o r _0-nitro compounds (53) s EtON0  B.  2  and  HO-N0 < 2  AcO-N0  <  2  0 N0-N0 <1 2  2  H 2  °-  N u c l e o p h i l i c S u b s t i t u t i o n on Carbon (Sj^) and Nitrogen Nucleophilic  the two  <T  s u b s t i t u t i o n i n n i t r a t e esters may  N 0  2  )  (S^.)  take place  on  neighbouring atoms of the e l e c t r o n r i c h oxygen namely on carbon  nitrogen*  1*  .A  XVII  It i s r a t i o n a l to assume t h a t nucleophie reagents (B:) with high e l e c t r o n density esters *  (Table  IV) would a t t a c k the more p o s i t i v e s i t e i n the n i t r a t e  In such a simple e l e c t r o s t a t i c model (XVII) t a k i n g no account of  s t e r i c e f f e c t s , i f co'ffthen S ^ r e a c t i o n should take place. r e a c t i o n s may reported  would predominate and  Under s p e c i a l circumstances ( « —  occur simultaneously.  S^. r e a c t i o n s  t)  S^ both  In p r a c t i c e , however, the number of  i s much l a r g e r than the number of S^,  i n d i c a t i n g that the p o l a r i z a t i o n of the of the C-0  i f 3T">c< an  0-N  reactions,  bond i s much l a r g e r than that  bond. " A l k y l a t i o n with n i t r a t e e s t e r s " i . e . the S  r e c e n t l y reviewed i n d e t a i l by Boschan and  xin  r e a c t i o n , has  co-workers (42).  One  of  been  the  - 27  c l a s s i c a l examples (54) of the S  -  r e a c t i o n i s the decomposition of  benzhydryl n i t r a t e e s t e r with primary or secondary amines such as p i p e r i d m e . On the b a s i s of the r e a c t i o n products i s o l a t e d one may according  to equation 22.  i n t e r p r e t the r e a c t i o n  However t h i s i s not the only r e a c t i o n which occurs  under these c o n d i t i o n s , the carbonyl e l i m i n a t i o n proceeds with the formation  simultaneously  of benzophenone but to considerably smaller extent  Weaker bases ( a n i l i n e , benzylamme) on the other hand gave almost c l u s i v e l y the corresponding product with N - C bond formation  (3:l)«  ex-  according  to  22. In c e r t a i n r e a c t i o n s such as b a s i c and n e u t r a l hydrolyses s o l v o l y s e s of n i t r a t e e s t e r s (55) or  mechanism i s operative  e i t h e r case (23^  and  (56) i t i s not obvious whether the S  since the products would be the same i n  24).  For t h i s reason T o f f e and  co-workers (57) studied the mechanism 18  of h y d r o l y s i s of s e v e r a l n i t r a t e esters by means of the technique. age may  According  0  isotope  to t h e i r f i n d i n g s the mechanism of h y d r o l y t i c c l e a v -  proceed by e i t h e r mechanism 25_ or 26_ depending on the s t r u c t u r e of  the n i t r a t e e s t e r i n q u e s t i o n . A change i n the hydrocarbon p o r t i o n may order of the r e a c t i o n (S^2  cause a change i n the  ^- S^l) and furthermore such a change  may  a l s o a l t e r the point of attack i n the a l k a l i n e h y d r o l y s i s of n i t r a t e esters from S,^. FhV  NC  »  S._ . T  These changes are summarized i n the s e r i e s 27:  NN  , n - a l k y l , sec. a l k y l , t e r t , a l k y l , P h ^ C - , H—  Extensive  V  —  S  NC  2  —  S  NC  1  ,  —  <2Z)  i n v e s t i g a t i o n has been made of sugar and r e l a t e d p o l y -  n i t r a t e s by t r e a t i n g them with n i t r o g e n bases (such as p y r i d i n e , p i p e r d m e ,  -28-  H  Ph  Ph  H  Ph  Ph  -N-----C H  r  ONO-  ONOu  i  •  H  (22)  Ph  H I  Ph  N-  C H 5  NO;  | Q  NH  C H 5  | 0  NH NO 2  Ph .Ph  +  3  /  H  H  PhCH ON0 2  t-BuON0  18  OH  +  +  2  2  OH  +  PhCH OH  2 H 0 2  t-BuOH  ^  -HC.-O-NO2  ^ C - 0 - N 0  2  +  L  8  H  O H "  1  8  \  N-  /  O  L O R  +  Q - C -  • ^ C - O "  O  OR  +  2  N 0  H 0* + 3  +  +  (23)  3  N 0  H  L 8  N0  3  ( 2  ( S  3  ONO,  •2  (  S  N  C  )  N N  4)  (25)  }  --OR (28)  - 2,9  hydroxylamine>  etc.) (24) (62).  -  In a l l cases f u l l or p a r t i a l  produced the parent a l c o h o l with r e t e n t i o n of c o n f i g u r a t i o n .  demtration T h i s proved  that the C-0 bond was not ruptured and t h e r e f o r e the n u c l e o p h i l i c subs t i t u t i o n took place on the n i t r o g e n (Sj^.).  In general such a r e a c t i o n  involves the formation of the a l c o h o l a t e anion as an intermediate (28) while the other component of the i o n p a i r contains the N - n i t r o base c a t i o n . During the customary working up procedure i n aqueous s o l u t i o n the alcohol a t e anion produced the corresponding a l c o h o l . In c e r t a i n cases s p e c i a l s t e r e o s e l e c t i v e d e m t r a t i o n took p l a c e . P y r i d i n e d e n i t r a t e d mannitol hexanitrate (58) s e l e c t i v e l y at equivalent C^, a t 25° (29). by s e l e c t i v e d e m t r a t i o n 50° (30).  D u l c i t o l h e x a n i t r a t e gave the p e n t a n i t r a t e  (59) on  and equivalent  with p y r i d i n e at  C e l l u l o s e 2, 3, 6 - t r i m t r a t e d e n i t r a t e d at  with hydroxylamine  or i t s  i n pyridine  selectively  (60)  ( 3 l ) . S i m i l a r r e s u l t s were obtained with  methyl(3 — D - g l u c o s i d e t e t r a n i t r a t e and hydroxylamine  i n pyridine ( 6 l ) .  In t h i s case (32) the 4 - ^ - n i t r o group, not present m  c e l l u l o s e , was  also  replaced by the hydroxyl group and t o a greater extent than the 2-O-^iitro group. Isohexide ( i . e . i s o i d i d e s 1, 4 j 3 , 6 - d i - 0 - a n h y d r o - L - i d i t o l (XVIII); i s o s o r b i d e t l,4j3,6-di-0-anhydro-D-glucitol (XLX); and 1,4;3,6-d 1-0—anhydro-D-mannito1 (XX)) d i n i t r a t e s  (62) and 1,2-  isomannide: cyclohexane-  d i o l d i n i t r a t e s (XXI) (XXII) (63) reacted with b o i l i n g anhydrous p y r i d i n e . K i n e t i c evidence (62) excluded the p o s s i b i l i t y of an S^, i n s t e a d of the parent d i o l s , as might be expected f o r meric m a t e r i a l was  mechanism and reactions, poly-  obtained as the c h i e f carbon-containing r e a c t i o n product.  -30 -  ONOo I ^ H-C-H I 0 NO—C—H I 0 NO-C-H  ON0  0  2  5  C  2  H  5  N  i  25°C  H—C—ONOo t 2  H-C-ON0  (29)  ONGv H-C-O  0  H-C-H  H—C—H  ONO.  ONO.  ONOg  ONC2 H-C-H  H-C-H  H-C-ONO? I 0 NO-C-H * I CuNO-C-H I H-C-ON0  H-C-ONOHO-C-H  0  2  2  H-C—H I ONOg  2  H-C-H I OoNO-C-H I HO-C-H I H-C—ONO-  C  5  H  5  N;  50°C  t  0 NO-C-H 2  H-C-ONOg H-C-H ONOo  ON0  2  H-C-H I CuNO-C-H I H-C —OH I 2  (30)  H-C—ONOg O^NO-C-H H-C-H l ON0  2  (32)  - 3 1  -  - 33 -  C.  O l e f i n (EQ_Q) and Carbonyl (E^_Q) E l i m i n a t i o n Reactions. The  d i f f e r e n c e between these e l i m i n a t i o n r e a c t i o n s _33_ and _34,  i s that  the double bond formed i s between carbon atoms i n one case, and between carbon and  oxygen atoms i n the other.  This v a r i a t i o n i n product formation r e f l e c t s a  d i f f e r e n c e i n the d e t a i l e d mechanism. hydrogen atom at the (b—position nucleophile (64).  In the case of o l e f i n e l i m i n a t i o n the  to the n i t r o x y group i s attacked  (33) and the r e a c t i o n i s thus f r e q u e n t l y c a l l e d  Carbonyl e l i m i n a t i o n represents  by  the  "(3-elimination"  a n u c l e o p h i l i c a t t a c k (34) on  hydrogen atom at the a — p o s i t i o n to the n i t r o x y group and  the  consequently i s c a l l e d  " (X -e 1 lminat I on" « These e l i m i n a t i o n r e a c t i o n s may p h i l i c s u b s t i t u t i o n on n i t r o g e n considerable  confusion  (Sj^) and  occur as side r e a c t i o n s t o n u c l e o on carbon (Sj^,), thus they caused  i n the older l i t e r a t u r e .  N u c l e o p h i l i c reagents ( l i k e HO  a t t a c k the p a r t i a l l y p o s i t i v e n i t r o g e n or (X—carbon i n n i t r a t e e s t e r s .  I f , how-  ever, by any means hydrogen atoms elsewhere i n the molecule become a c i d i c to such an extent that t h e i r e l e c t r o p h i l i c i t y becomes comparable to that of the n i t r o g e n or ex,-carbon atom then i n a d d i t i o n to n u c l e o p h i l i c s u b s t i t u t i o n e l i m i n a t i o n r e a c t i o n s a l s o w i l l take p l a c e . In the a l i p h a t i c s e r i e s the percentage of o l e f i n i c e l i m i n a t i o n i n creases with the branching of the chain; i . e . with the s t a b i l i t y of the mediate carbonium i o n .  Both second and f i r s t order r e a c t i o n s  place i n o l e f i n e l i m i n a t i o n while carbonyl bimolecular.  4  coworkers (65)  ( c f . 33) may  take  e l i m i n a t i o n (34) seems to be always  Comparable f i g u r e s f o r the two  from the data of Baker and  inter-  r e a c t i o n s are given i n Table V  (66).  )  - 33 -  Table V. E l i m i n a t i o n Reactions with N u c l e o p h i l i c Reagent OH Solution  E  c=c  CH CH ON0 3  2  20°  2  (CH,)  CH0N0 2 (CH ) CONQ  o  k x 10 60°  w  2  * Nitrate Ester  20°  5  ' 60°  2  0.08  14.5  0.09  <L  3  3  23  2  PhCH20N0  PhCH(CH )0N0 3  (Ph) CH0N0  2  -  20°  k x 10 20°  -  -  -  9.24  847 0.33  5  0.016  -  3.0 1.0  60°  0.09  13.7  -  5  0.21  4.8  8.1  -  60°  87  1  2  260*  -  90  RiCHgCHgONGg  2  1.54**  -  2  i n 90$ Aqueous Ethanol  0.127 31.7  )  E x t r a p o l a t e d from values observed a t 0 , 20 and 30 $ kxlO = 0.06; 1.54 and 5o5 r e s p e c t i v e l y . Because of d e v i a t i o n s the true value may l i e between 130 and 460.  ^  F i r s t order r e a c t i o n :  E  n  _1.  N u c l e o p h i l i c reagents other than OH reactions. carbonyl  a l s o cause carbonyl  elimination  A r a l k y l n i t r a t e esters y i e l d e d almost e x c l u s i v e l y the corresponding  compounds with anhydrous p y r i d i n e  (35) (67) (36)  (68).  - 34 -  A d e t a i l e d study of the e l i m i n a t i o n mechanism i n benzyl n i t r a t e has been c a r r i e d out r e c e n t l y by means of k i n e t i c isotope techniques (69). Both the 5.04 deuterium isotope e f f e c t and the 1.02 nitrogen-15 isotope e f f e c t  ("which i s  one of the l a r g e s t observed f o r n i t r o g e n i n a r a t e process") favoured a concerted mechanism (37) over a two step carbanion mechanism (38) f o r carbonyl e l i m i n a t i o n (Table V I ) . m  A value of 1.16 f o r the secondary deuterium isotope was i n d i c a t e d  the n u c l e o p h i l i c s u b s t i t u t i o n .  No s i g n i f i c a n c e , however, was attached t o the  d i f f e r e n c e between t h i s value and u n i t y because of the r a t h e r large  percentage  e r r o r i n the determination of the small amount of n i t r a t e i o n .  Table V I . Isotope E f f e c t s i n the Reaction of B e n z y l n i t r a t e with Sodium Ethoxide i n Absolute Ethanol a t 60.2 . PhCH 0N0 2  PhCD 0N0  2  2  ?|E 2  88.7  64.4  foS^  11.3  35.6  C0  k  t o t a l x 10  ^^2  x 10 x 10  3  3  VV  S f l  1 4  12.3  2.44 1.35 5.04 ± 0.25  2  (k /k^ )E  3.79  1.57  3  (k^k^E^ (  13.9  ^  5  C ( )  2  1.0196 ± 0.0007  2  - 36 -  D„  Homolytic Decomposition  of N i t r a t e E s t e r s  Presumably both thermal decomposition  (70) and explosion (T3J of  n i t r a t e e s t e r s proceed v i a a f r e e r a d i c a l mechanism.  The p r i n c i p a l cleavage  occurs between the e s t e r oxygen and n i t r o g e n atoms with the formation of a l k o x y l r a d i c a l s (39)» R0N0  -  2  RO'  +  N0  (39)  2  This c o n c l u s i o n was confirmed by several authors working e i t h e r on slow t h e r molysis with the a i d of r e a c t i o n k i n e t i c s or on flames (combustion) i n f r a r e d technique.  utilizing  Equation _39 thus i n d i c a t e s that homolytic cleavage takes  place according t o mode of s c i s s i o n 4 (Figure 4 ) . A number of simple primary a l i p h a t i c n i t r a t e e s t e r s have been s t u d i e d by both of the above techniques and the r e s u l t s from the thermolysis of n—propyl nitrate  (72) support a degradation scheme e s s e n t i a l l y s i m i l a r t o that postulated  for ethyl nitrate (40). CEjC^CI^aTK^  - N0 +CH CH CH 0. 2  3  2  CH^H^+CILjO  2  (40)  However, i t i s not c e r t a i n whether the i n i t i a t i o n proceeds according t o 40 or by intramolecular rearrangement CH CH CH 0N0 3  2  2  -  2  of the b i r a d i c a l formed i n 41.  H0N0+(.CH CH CH 0.) 2  2  2  - CH^^+C^O  Further r e a c t i o n may occur v i a a t t a c k of the o r i g i n a l ester by N0  (41)  2  or HONO (but  not C H^.0»), i n agreement with a "chain thermal" process suggested by Gray and 3  Xoffe (73) f o r the i g n i t i o n s of methyl and e t h y l n i t r a t e s (42 and 4 3 ) . N0 +GH CH2CH 0N0 2  3  2  N0 +CH GH GH ON0 2  3  2  2  HONO+tCILjCH^^ONO^  2  2  HONQ+^CHCHtjONOg)  CH^B^+R^CO+NOg  ~ CH CH0+H C0+N0 3  2  (42)  (43)  -  -37  The decomposition of the secondary i s o p r o p y l n i t r a t e e s t e r showed close analogy to t h e p a t t e r n observed i n the case of the normal isomer (44).  CH, 3  H  N  .C  CH  X 3  /  CH, x  H  3  -  0N0  NO-  +  CH  2  C X  3  /  H CH«  v  0.  suggested furthermore (72)  It was  e s t e r s as i n 45 and 46 »  +  CH  -C.  /  (44)  0  J  that the NC^  attacks the n i t r a t e  A remarkable d i f f e r e n c e has been observed (74), how-  ever, i n the flame decomposition of butanediol d i n i t r a t e s with r e s p e c t to that of monoesters«  "The r e s u l t s i n d i c a t e that these e s t e r s {2, 3-butanediol d i n i t r a t e  and 1, 4-butanediol d i n i t r a t e ) i n c o n t r a s t to those of mononitrates so f a r s t u d i e d , break down i n a unimolecular f a s h i o n " according t o 47 and 48. t r a c e s of the suspected intermediates a c e t o m  (XXIII) and d i a c e t y l  Only  (XXIV) were  found among the products. N i t r a t e e s t e r s w i t h more complex s t r u c t u r e were a l s o i n v e s t i g a t e d . Glycerol t r i n i t r a t e dinitrates  (47).  (75) showed a close analogy to the decomposition of v i c i n a l  The f i r s t  step i n the thermal decomposition i s probably the  s c i s s i o n of an 0~N bond (49).  There are, however, two p o s s i b i l i t i e s  n i t r o g l y c e r i n e has both primary and secondary n i t r o x y groups.  since  Both of these  a l k o x y l r a d i c a l s (49) w i l l y i e l d e s s e n t i a l l y the same products according t o (50). Recent p u b l i c a t i o n s of Wolfrom and co-workers (76)  (77)  (78)  vide some i n t e r p r e t a t i o n of the c e l l u l o s e n i t r a t e thermal decomposition. t e r e s t i n g r e s u l t s were obtained by means of ^ C  - labelled cellulose  proIn-  (mostly  at  p o s i t i o n 2 and 5) which gave an i n i t i a l p a t t e r n f o r the thermal degradation  of  c e l l u l o s e n i t r a t e as shown i n 51. In  s p i t e of the e a r l y (1901) p i o n e e r i n g work of W i l l  (79) on n i t r a t e  s t a b i l i t y , k i n e t i c studies of thermal decomposition have been c a r r i e d out i n a  - 38 -  *3 N0  C N  /H  +  2  • HC3  H  N0  CH3-NC2  +  2  3  ON0  C V  /  ^  H  DN0  H3C ONQ  or  +  CH3-CHO + N 0  (45)  2  CKj-O-NO  2  V C=0  C  +  HONO  + N0  ( 46)  2  HjC  2  2  CHj- C H - C H —CHj ON0  -  2 CKj-CHO  +  2 N0  (47)  2  2  ONO, C  C H ^ C H 2— C H  ONO  CHgO  2  2  + CH^CHg*  2 N0  (48)  2  0  OH  O O 11 n C H 3 - C — C • -CH-,  O  CH3-CH—C-CH3 XXIII  XXIV  CH —CH—Ch^ 2  CH. ON0  -CH2  ON0  CH. 2  N0  ON0  ONC2 O '  +  2  2  ONC2 ONC2  CH  A."  2  (49)  2  ON0  C H — CH  ON0  CHgO + C H — C H .  2  CH^-CHO +  2  2  ON0 0«  2  N0  2  ONCg  O N O , ONOg  (50) CH -CHO 2  NO, +  ONO,  2  6  ^ O N 0  <  CH 2-CHO  T  o-  H« +  CH 0 2  OHC—CHO  6  2  H CO 2  H/ o  C0 H  HCO +  6NO  2  2  +  HCOOH  1 2 OHC—CHO  (51)  - 39 -  Table V I I . Log Frequency F a c t o r s and A c t i v a t i o n Energies f o r Thermal Decomposition of N i t r a t e E s t e r s .  l o g A(sec~"'') CH CH ON0 3  2  2  CH CH CH 0N0 3  2  2  2  E  a  (kcal/mol)  Year  Ref.  16.85  41,23  1954  81  14.7  36.86  1949  82 cf42  0 N0GH CH 0N0 2  2  2  2  C^NOCILjCH (0N0 JCl^ONC^  15.9  39.0  1947  83  13.6  35.0  1959  84  17.1  40.3  1947  83  18.95  43.7  1955  85  32.8-35.8  1961  86  15  37  1960  62  14.18  30.0  1961  62  13.76  29.7  1958  88  2  Nitrocellulose  Isosorbide d i n i t r a t e C10N0 FON0  2  2  -  - 40 -  more elaborate way  only i n the l a s t 15 or 20 y e a r s .  The unimolecular decompo-  s i t i o n of n i t r a t e e s t e r s followed Arrhenius' r a t e equation (52). -Ea k = A.e  (52)  R T  The apparent a c t i v a t i o n energies, E  (kcal/mol), and l o g frequency  f a c t o r s , l o g A (sec "*"), f o r r e p r e s e n t a t i v e e s t e r s are summarized i n Table V I I . Although one would expect some s o r t of c o r r e l a t i o n between s t r u c t u r e and r e a c t i v i t y ^ one should t r e a t these r a t e constants c a u t i o u s l y because two or more types of decomposition may  take place simultaneously.  Furthermore,  the measurements were c a r r i e d out by d i f f e r e n t experimental techniques  m  d i f f e r e n t l a b o r a t o r i e s and because of the large v a r i a t i o n s i n the values no g e n e r a l i z a t i o n seems permissable. Steinberg and co-workers (80) reported d i f f e r e n c e s i n the burning rates,  k(cm/sec)$ of ordinary and deuterated n i t r a t e e s t e r s .  As the degree  of d e u t e r a t i o n increased the burning r a t e s were decreased e x t e n s i v e l y . For example, perdeutero—isopropyl n i t r a t e d i d not even burn under the experimental conditions.  The isotope e f f e c t s obtained are summarized i n Table VIII. I t has  not been determined  as y e t whether these e f f e c t s are comparable with those  k i n e t i c isotope e f f e c t s which might have been observed i n slow thermal decomposition*  Table V I I I The E f f e c t of Deuterium S u b s t i t u t i o n on Burning Rates of N i t r a t e E s t e r s (80).  V1^  Compound CD CD 0N0 3  2  1.4  2  (ca ) cjiom 3 2  2  1.26  (CD ) CH0N0  2  (CD ) CD0N0  2  3  3  2  2  1.54 CO  The Photochemistry of the N i t r a t e  and  Related Compounds.  Esters  - 42 -  P h o t o l y s i s of the ^C-O-X group where X may be halogen. -OR, -NO, or -NO^ i s of current i n t e r e s t ,  (89)(90).  i n general  v i a f r e e r a d i c a l intermediates  as transformations  Photochemical r e a c t i o n s are  provides an a l t e r n a t i v e route t o thermolysis  considered  and thus p h o t o l y s i s  f o r the decomposition of n i t r i t e  and n i t r a t e e s t e r s by f r e e r a d i c a l mechanisms. A recent review (9l) on the p h o t o l y s i s of n i t r i t e e s t e r s , RONO, summarized the s y n t h e t i c p o t e n t i a l of the technique. i s considered  The p h o t o l y t i c decomposition  t o proceed v i a a homolytic 0—NO bond cleavage which provides  n i t r i c oxide and a l k o x y l r a d i c a l .  The a l k o x y l r a d i c a l thus formed has  t i v e l y short l i f e t i m e and may undergo f u r t h e r transformation possible routes.  a rela-  by one of s e v e r a l  The products i s o l a t e d thus e n t i r e l y depend on the route  " s e l e c t e d " by the r a d i c a l and the " s e l e c t e d " mechanism i s a f u n c t i o n of the intra—and intermolecular Alkyl nitrites e x c i t a t i o n (92).  chemical environment. (XXV)  e x h i b i t a number of p o s s i b i l i t i e s f o r e l e c t r o n i c  The lowest energy (longest wavelength) t r a n s i t i o n (^3600 X )  seems t o be (93) an n_ —+• <\t* e x c i t a t i o n since the non-bonded e l e c t r o n s of T  trans-  cis XXV  nitrogen  XXVI  (x) are the most l o o s e l y bound and i n t h i s e x c i t a t i o n one nonbondmg  e l e c t r o n of n i t r o g e n i s t r a n s f e r r e d t o the lowest empty antibondmg (i.e.  TT *) o r b i t a l .  TC  The nonbonded e l e c t r o n s of oxygen ( • ) are more t i g h t l y  bound because of the greater e l e c t r o n e g a t i v i t y of oxygen and thus t h e i r e l e c t r o n i c  - 43  excitation n ^ — »  T£*  requires higher energy ( i . e . shorter wavelengths)  seemingly around 2700 £ (Figure 5). TT  intense Tt  -  At even shorter wavelengths i s the very  •» Tt * band representing the excitation from a low energy level  orbital (o) to the antibondmg Tu  orbital ( TT *)»  Conehtiifaly  Apparently i t has not been determined as yet which one of these exA  citations brings about the suggested 0-N0  bond cleavage i n solution photolysis.  It i s possible that one of the two low energy excitations,  TT * or  n,Q  —  TC*^ or both of them are responsible for the photolysis since the  n^  •» TL* excited n i t r i t e ester readily decomposed i n the gaseous phase  (94).  In nitrate esters, however, the nitrogen atom does not possess nonbondmg electrons, therefore, the corresponding absent from the spectrum (Fig. 6 B). Tt  long wavelength absorption i s  On the other hand there are twice as many  and XIQ electrons i n the nitroxy group (XXVI) as i n the oxynitroso group  (XXV).  - 44 -  Figure  5.  A:  Energy Levels of Molecular O r b i t a l s and P o s s i b l e E l e c t r o n i c Transitions for N i t r i t e Esters.  B:  T y p i c a l E l e c t r o n i c Spectrum of a N i t r i t e E s t e r (2-butyl n i t r i t e i n ether (95)). The dotted l i n e s represent the estimated separation of the various t r a n s i t i o n s .  Figure  6.  A:  Energy Levels of Molecular O r b i t a l s and P o s s i b l e E l e c t r o n i c Transitions for Nitrate Esters.  B:  T y p i c a l E l e c t r o n i c spectrum of a N i t r a t e E s t e r (2-butyl n i t r a t e i n ethanol (95)). The dotted l i n e s represent the estimated separation of the various t r a n s i t i o n s .  - 45 -  No systematic  study of the e l e c t r o n i c spectra of n i t r a t e e s t e r s has  been published as y e t but Rao (96) suggested that the shoulder a t 2700 & i s r e a l l y due t o an n  — TU* t r a n s i t i o n , while the high i n t e n s i t y band,at the  shorter wavelength would represent  the TC ——*- 1T * e x c i t a t i o n , A t y p i c a l  n i t r a t e ester spectrum together with an i l l u s t r a t i v e energy l e v e l diagram* i s shown i n Figure 6* Very l i t t l e i s known about the photochemical behaviour of n i t r a t e e s t e r s . P h o t o l y s i s of e t h y l n i t r a t e i n the gas phase with the 2537 A* l i n e s and 2650 1 of the mercury a r c l e d t o the conclusion that the oxy-nitro bond s c i s s i o n i s the predominant r e a c t i o n of the e x c i t e d n i t r a t e e s t e r molecule*  Equations J53_  to J58 seemed t o e x p l a i n the observations (99); (1.00)  C^ONO^*  C H 0.+N0  (0.53)  0^0*  CRy-K!H 0  (54)  (0.47)  C H 0.  B>+CH -CH0  (55)  2  2  5  3  CRj* +N0  (0.045)  CBy+C^OM^  2  H*KJ H 0N0 2  (53).  2  2  (0.485)  (0.37)  5  5  ~  CH N0  •  C H 0CH +N0  3  2  ( 56)  2  5  3  C H 0H+N0  2  2  5  2  (57)  2  ^  The gaseous phase p h o t o l y s i s of n i t r i t e and n i t r a t e e s t e r s by s u n l i g h t i s a l s o a current problem of a i r p o l l u t i o n (100). A recent Japanese patent (101) seemed t o confirm the f r e e r a d i c a l nature of the photo-decomposition fragments of n i t r a t e e s t e r s i n s o l u t i o n since the esters (generated i n s i t u from a l c o h o l , inorganic n i t r a t e , and acid) were claimed t o f u n c t i o n as polymerization  a c c e l e r a t o r s when i r r a d i a t e d during the  preparation of c r y s t a l l i n e polymers.  A d e t a i l e d study some years ago (102)  *) These energy l e v e l diagrams (Figure 5 A and 6 A) were constructed by analogy t o those of N 0 ( l l ) , $(£(97) and Na ~CH N0 (98). 2  2  2  46  -  proved t h a t thermolysis of a l k y l n i t r a t e a l s o a c c e l e r a t e d a d d i t i o n a l p o l y m e r i z a t i o n of methyl methacrylate v i a a f r e e r a d i c a l mechanism,, of a l k y l n i t r a t e s as "ant1—knock"  The  efficiency  additives i n gasolines points to a similar  mechanism. The photo-decomposition by Claesson and co-=woikers (103)  of c e l l u l o s e n i t r a t e has been r e c e n t l y s t u d i e d (104).  F u l l y and p a r t i a l l y n i t r a t e d  cellulose  samples (13.87 and 12,12$ N r e s p e c t i v e l y ) were photolysed with 99*5$ monochromatic  l i g h t of 2537 %»  cometncally.  I t was  The extent of depolymerization was  found t h a t the quantum y i e l d s f o r the depolymerization  d i d not d i f f e r g r e a t l y f o r the two samples being 0.02 c e l l u l o s e and 0*01 presence  followed v i s -  f o r the f u l l y n i t r a t e d polymer.  of an a c t i v e group (—OH)  i n the molecule  f o r the p a r t i a l l y n i t r a t e d  T h i s might i n d i c a t e t h a t the  aided the d e p o l y m e r i z a t i o n .  On  the other hand the p o s s i b l e occurrence of r e a c t i o n s other than d e p o l y m e r i z a t i o n was  not excluded and the low quantum y i e l d of depolymerization might mean t h a t  most of the l i g h t quanta were u t i l i z e d f o r other processes. A wavelength dependence study  (104) i n d i c a t e d t h a t while the  ness of the l i g h t quanta was  roughly the same at 2537 and 3020 jL  l i g h t at 3340 and 3650 A* was  practically inactive.  mono chr omatlc  On the other hand the  l i z a t i o n of (o -*aphtbylamme as p h o t o s e n s i t i z e r caused even a t the lower energy wavelengths (3340 and 3650 A*)» t a i n e d , however^ was  effective-  uti-  photo-<Lepolvmerization The quantum y i e l d  ob-  lower by about an order of magnitude (0*0006) i n d i c a t i n g  that the e f f i c i e n c y f o r energy t r a n s f e r from naphthylamme t o n i t r o x y group i s l e s s than  10$  o  The e f f e c t i v e s p e c t r a l r e g i o n f o r the p h o t o l y s i s of n i t r a t e e s t e r s has been determined  r e c e n t l y i n t h i s l a b o r a t o r y (105) to be 2650—3340 £, at  the t a i l — e n d of the c h a r a c t e r i s t i c suggested n  UV — a b s o r p t i o n (Figure 6 B) where the  »• TT * band i s l o c a t e d .  In the same study the p h o t o l y s i s of  - 47  -  25 d i f f e r e n t n i t r a t e esters i n both ethanol sence of diphenylamme was  reported.  The  and benzene s o l u t i o n s i n the p r e -  experiments were c a r r i e d out at  15°C  with the u n f i l t e r e d mercury arc spectrum and an approximately l s l molar r a t i o of n i t r a t e e s t e r and diphenylamme.  For the d e t a i l e d study i s o s o r b i d e d i n i t r a t e —2  (l,4}3,6-dianhydro-D-glucitol-2,5-dmitrate) (XLX) was  used i n 2-4x10  molar  s o l u t i o n s and n i t r o — and n i t r o s o - diphenylammes were i d e n t i f i e d among the products  (59)• There were two  p o s s i b l e mechanisms f o r the photodecomposition which  would r a t i o n a l i z e the experimental r e s u l t s . e s t e r was  In the f i r s t , the e x c i t e d n i t r a t e  thought to break up to a l k o x y l r a d i c a l and n i t r o g e n dioxide  in a  manner s i m i l a r to t h a t proposed f o r the gas phase p h o t o l y s i s of e t h y l n i t r a t e (53).  The  a l k o x y l r a d i c a l would then r e a c t f u r t h e r e i t h e r by decomposition to  fragments or by attack on other molecules. scavenged by the diphenylamme.  The  n i t r o g e n dioxide would be  In t h i s model the o r i g i n of the small amount  of nitroso-compounds formed remained unexplained since an intermediate l y s i s of N0  to NO  2  and 0 would be l e s s l i k e l y because NO  photo-  i s not very r e a c t i v e  toward organic compounds as a n i t r o s a t i n g agent. The  second a l t e r n a t i v e was  r e l a t i v e l y long l i f e t i m e and molecules.  that the e x c i t e d n i t r a t e ester had  a  could undergo r e a c t i o n s with the neighboring  This would provide an explanation  f o r the o r i g i n of the n i t r o s o -  compounds by assuming t h a t e x c i t e d n i t r a t e e s t e r s would be reduced to n i t r i t e e s t e r s by simultaneous o x i d a t i o n of the surrounding compounds. reduction nitrates  of the —NC^ (4) and  group has been reported  i n the photoisomerization  dehyde to _o-nitrosobenzoic  acid  S i m i l a r photo*  i n the p h o t o l y s i s of  (106)  (107)  (108)  inorganic  of _o-nitrobenzal-  (60).  I f the f i f t h mode of cleavage f o r the e x c i t e d n i t r o x y group (Figure was  accepted then both the e x c i t e d n i t r a t e and n i t r i t e e s t e r s might r e a c t with  4)  - 48 —  -  49  -  diphenylamine p r o v i d i n g an exchange of -NO^ and -NO groups with the amine hydrogen and the N—nitro and N-nitroso compounds thus formed would undergo intramolecular rearrangement. The recent d i s c o v e r y (109) that both of the isomeric mononitrates as w e l l as the parent d i o l were present among the photo—products i n appreciable q u a n t i t i e s i n d i c a t e d that i n the predominant course the r e a c t i o n proceeded v i a mononitrates t o the parent d i o l and that 0—N0  2  without  groups were replaced by OS.  i n v e r s i o n a t the asymmetric carbons ( 6 l ) .  This r e s u l t would seem t o  favour the second proposed mechanism. Since the amount of information concerning the photochemistry of the n i t r a t e e s t e r s was l i m i t e d i t was considered u s e f u l t o make comparisons with the photochemistry of r e l a t e d nitrogen—oxygen compounds (Table EC).  T h i s idea  was based on the assumption that there i s a c o r r e l a t i o n between the UV—absorpt i o n of X-N0  2  compounds and the s t r u c t u r e of X.  No r e p o r t of such an a n a l y s i s  was a v a i l a b l e but a s i m i l a r c o r r e l a t i o n between the UV - s p e c t r a (the n ^ — * • TC* band) of (R^^XNO compounds and the nature of X has been pointed out (93) (Table X ) ,  The r e g u l a r change observable  s o r p t i o n ( l l O ) (Table XI) and i n molecular  i n the i n f r a r e d ab-  geometry (Figure 7) of the ( R ) XNO, n t molecules ( i l l ) as X was v a r i e d seemed t o j u s t i f y t h i s analogy. 1  -  T A B L E  Structural  IX  50  -  Properties  of  Nitrogen-Oxygen  Compounds  N==0 Valence electrons  11  •  N-O  1150  A  ••  :N -.  electrons  ONO  Ii •.O; 16  18  1 7  115.4°  134 1°  1  1.188  236A  \  P ;  H electrons  1.154  - P v  » P  :F-N  o  24  0 24  24  127°  ONO  180  A  H  Valence  ^-  11  N+  "9:  Valence  N—O  •O-  N •  24  130°  125°  23A  N-O  1 22 A  1 206  A  1  X-N  1.48A  1405  A  1 35  H H  / HT  Valence  -*  C-N  electrons  P  • - /P  :O-N  \  O  0  —  24  24  —  120,5°  </_ O N O N-O  1.24  X-N  1  H / H  C  ' \  Valence 30  electrons  Z.ONO  .. P °  H  /  N  CH  -  N  30  v  A  2 5 A  CHo  ,0  •.O-N  °  "  N  o  30 125  3°  N-O  1 26  A  X-N  1.36  A  Values  taken  from  (133)  —  A  0°  A  - 51 -  Table X — « - T C * T r a n s i t i o n s of (R^^XNO Compounds  i>x *  X  * (i)  (R ) XNO, 1  n  (kcal/mole)  c  2.50  (CH ) C-NO  6650  s  2 45  (CH ) CS-NO  5988  CI  3.10  Cl-NO  4600  N  3.15  (CH ) N^NO  3610  0  3.60  CH (CH ) 0-NO  3560  F  4.15  F-NO  3110  *)  3  0  3  3  3  3  3  2  2  3  Values taken from (13).  Table XI Fundamental I n f r a r e d Type of V i b r a t i o n ^stret.  Frequencies (cm" ) of (R1) XN0O Compounds n 2 1  CH -N0 3  HO-N0  F-NO,  2  2  (N0 )  1562  1540  1675  1779  (N0 ) 2  1377  1379  1300  1306  deform (ONO)  657  709  680  466  919  1043  925  821  2  as stret. sym  stret. (x-^o ) 2  _ <ks + ysym  1  4  7  0  *•  1460  1490  1552  NO  P h o t o l y s i s of NO Mercury p h o t o s e n s i t i z e d  decomposition  of n i t r i c  oxide i n the gaseous  phase has been s t u d i e d by Strausz and Gunning (112) and N_, N 0« and higher ?  - 52 -  1 30  1.40 X-NQ  FIGURE  7  Correlation m (R') XNQ n  of 2  Z_  ONO  Compounds  and  1 50 2  Bond  X-N0  Length  2  Bond  (A)  Length  - 53 -  oxides of n i t r o g e n were found t o be major products. was  The r a t e of p h o t o l y s i s  l i n e a r l y p r o p o r t i o n a l to the i n t e n s i t y of the 2537 A* band. According t o the proposed mechanism e x c i t e d NO molecules form an  energy-rich dimer$  (NOjg, which underwent a stepwise decomposition process  i l l u s t r a t e d i n 65_ and 66: Hg  +  hs>  Hg* + NO NO* + NO (NO)  2  Hg*  (62)  NO* + Hg  (63)  (NO)*  (64)  »»  (NO)* + NO  ~  N  + oxygen  2  N0 2  + N0  (65_) (66)  2  P h o t o l y s i s of NO i n benzene s o l u t i o n produced unexpected products as r e c e n t l y reported by Kemula and Grabowska (113). phenol and 2,4-dinitrophenol and the absence  The formation of .o-nitro-  (or questionable presence) of _p_—  or m- n i t r o p h e n o l could not be explained by a simple r e a c t i o n mechanism. The primary process was explained i n terms of the forbidden s m g l e t triplet  S ) e x c i t a t i o n * of benzene since the mixture was  (T  q  irradiated  with a wavelength range of 2900-3600 X and from previous experiments (117) i t was c l e a r t h a t the r e g u l a r l y forbidden s m g l e t - t r i p l e t absorption would  appear  i n t h i s range of wavelengths i n the presence of paramagnetic species l i k e  NO  or O^* I t was proposed t h a t the e x c i t e d t r i p l e t state of benzene (which acts as a b i r a d i c a l ) ,  being i n contact with the paramagmetic NO molecule, produced  the  nitrophenols i n some unknown manner (67)•  C o n t r o l experiments were c a r r i e d  out  with oxygen (118) and i n a d d i t i o n t o minor amounts of o-qumone, phenol was  i s o l a t e d as the major product (68).  — T h i s e l e c t r o n i c t r a n s i t i o n i s forbidden by the " s p i n momentum conserv a t i o n " r u l e of quantum mechanics (114) (115) (116),  - 54 -  P h o t o l y s i s of NO, The gas phase p h o t o l y s i s of n i t r o g e n d i o x i d e was i n v e s t i g a t e d by N o r r i s h (119)  (120) as e a r l y as 1929. Recent reviews ( l 2 l ) (122) proposed  seven d i s t i n c t i v e mechansims (depending on the r e a c t i o n c o n d i t i o n s ) i n terms of  f i f t e e n equations.  " I t now appears that below 3700 A* atomic oxygen i s an  important product of the primary photochemical process" (120) according t o 69. NO, ^  »  N0  —  2  (69)  NO + 0  The r e a c t i o n o f n i t r o g e n d i o x i d e with aromatic compounds was r e viewed by Riebsomer (123).  "Reaction may be brought about by h e a t i n g t o 80°  i n sealed tubes, by the a c t i o n of l i g h t  (4000-7000 £ ) a t 55-60°, or by a glow  discharge i n a Siemens tube" (124). P h o t o l y s i s of HN0  3  The decomposition of n i t r i c a c i d by l i g h t was d e s c r i b e d i n the l a s t century by B e r t h e l o t  (125).  A more d e t a i l e d study of the r e a c t i o n as reported  by Reynolds and T a y l o r (126) i s summarized by equation 70. light 4 HN0  3  dark  (fast) (slow)  2H 0 + 2 N 0 2  2  4  + 0  2  (70)  According t o the authors "the decomposition may p o s s i b l y take place i n stages, the f i r s t product being n i t r o u s a c i d and oxygen, the former and the excess n i t r i c a c i d then producing water and n i t r o g e n peroxide" as represented i n equation 71, 72, 73. H0-N0 +  HO-NO  +  0  H0-N0 +0  HO-NO  +  0  H0N0„+H0N0  H„0 +  2  2  2  -  2  (71) 2  (72)  N„0„  (73)  2 4  —  T h i s r e a c t i o n would thus support the suggested f i f t h mode of s c i s s i o n of n i t r a t e e s t e r s (Figure 4)«  -55  -  - 56 -  The r e s u l t s of Co  - r a d i o l y s i s of HNO^ suggested  (127) t h a t both  the f o u r t h and f i f t h modes of s c i s s i o n occurred simultaneously under h i g h  energy  i r r a d i a t i o n (74) (75). H0N0  2  —  HON0  *- HO*  2  »  HON0  HN0  HON0  2  2  + 2  N0  +  (74)  2  ^  (75)  P h o t o l y s i s of N0~ N i t r a t e ions undergo photochemical N0  2  r e d u c t i o n i n aqueous s o l u t i o n t o  which i n t u r n i s transformed t o hydroxylamine.  The photoreduction occurs  r e a d i l y i n the presence of simple organic substances a t the cost of t h e i r simultaneous  oxidation (4).  Inorganic n i t r a t e s were photolysed i n the presence of diphenylamme by Coldwell and McLean (128)  (129).  Nitrodiphenylamines were i s o l a t e d as i n  the case of the p h o t o l y s i s of covalent n i t r a t e s (59)(105) but no evidence of n i t r o s o d e r i v a t i v e s was found. P h o t o l y s i s of CBLjN0  2  Nitromethane i n argon matrix a t 20°K has been photolysed and the nature of the products s t u d i e d by i n f r a r e d spectroscopy (130).  The homolytic  cleavage  according t o equation 76 has been r u l e d out by the absence of N0 , CH^ and C Hg« 2  ^  CHj-NOg  cny  The p h o t o l y s i s was performed of a high pressure (A-H6) spectrum.  +  NO  2  (76)  2  on s o l i d CH^NC^ and CD^NOg with the a i d  (Figure 45) or medium pressure (A-H4) mercury arc  The stepwise transformation i s described by 77 where the major pro-  ducts were CR^O.  CO,  C0 , 2  CH^-N0  2  ^  N 0, 2  -  NO,  CE^O-NO  H 0,  HOCN, and HNO.  2  ^  a  -  products.  (77)  The f a c t t h a t methyl n i t r i t e was formed e x c l u s i v e l y as the t r a n s i s omer a t 20°K provided i n t e r e s t i n g evidence f o r the mechanism.  Although more  - 57 -  than one t e n t a t i v e mechanism has been suggested, i t seems r a t i o n a l t h a t the methyl group p a r t i c i p a t e d m  a s t e r e o - s p e c i f i c manner m  the rearrangement by  a s s o c i a t i o n with one of the oxygen atoms of the e x c i t e d NO,  group.  P h o t o l y s i s of P y r i d i n e N-oxides P y r i d i n e N—oxides are somewhat analogous t o —NO,  groups since  one  doubly bonded oxygen of —NO,  may be considered as replaced by the aromatic  double bond.  No n^  e x c i t a t i o n i s p o s s i b l e but the group e x h i b i t s  both n —«-7t o  and  *• II  H>—»• tc  t r a n s i t i o n s (131).  I r r a d i a t i n g p y r i d i n e N-oxide at two d i f f e r e n t wavelengths  (132)  produced i n both cases (78, 79) p y r i d i n e and atomic oxygen (which i n t u r n caused some d e s t r u c t i v e oxidation) resonance lamp) caused an n — v Hg resonance lamp) produced a  i n s p i t e of the f a c t that 3261  (pyrex Cd  TC* t r a n s i t i o n while the l i n e at 2537 £  (quartz  TC—•-TiT* e x c i t a t i o n .  On the other hand when the Ov- p i c o l i n e N-oxide was i r r a d i a t e d at the same two wavelengths, the products of the p h o t o l y s i s v a r i e d according to the wavelength a p p l i e d .  In the  * case the  c\-methyl group d i d not  e f f e c t the course of decomposition (80), while i n the n  3»tC* e x c i t e d s t a t e  the CX -methyl group acted as an oxygen acceptor (81)analogous to the formyl group i n the o»»nitrobenzaldehyde  photorearrangement  (60).  These r e s u l t s were c l e a r demonstrations of the chemical d i f f e r e n c e s of the two types of e x c i t e d states ( 'HT — » - T C * and n —*-'VU*)# even so, t h i s d i s t i n c t i o n was not always r e f l e c t e d i n the product f o r m a t i o n .  RESULTS  AND  DISCUSSION  - 59 -  I*  Synthesis of Aromatic N i t r a t e  Esters.  I t has long been known (53) that i n n i t r i c a c i d - s u l f u r i c a c i d n i t r a t i o n nitronium i o n , NO^, i s a c t u a l l y the n i t r a t i n g s p e c i e s .  Although t h i s mixed  a c i d i s a powerful and widely used n i t r a t i n g agent i t has been e s t a b l i s h e d t h a t f o r the n i t r a t i o n of s e n s i t i v e more d e s i r a b l e (24).  polyols n i t r i c acid-acetic  anhydride mixture i s  The question of the i d e n t i t y of the n i t r a t i n g agent i n  the  l a t t e r mixture, however, remained u n s e t t l e d u n t i l r e c e n t l y .  and  CH^COONO, (135)  Both N , 0 ^ (134)  were proposed as the n i t r a t i n g agent i n agreement with Raman  spectroscopic evidence (136), however, NO," also has been detected by i n f r a r e d spectroscopy (137) i n concentrated s o l u t i o n s Recent k i n e t i c i n v e s t i g a t i o n s entity.  of n i t r i c a c i d i n a c e t i c  anhydride.  confirmed nitronium ion as the n i t r a t i n g  Equations 82, 83, 84 were proposed (138) t o f i t the experimental r e s u l t s ,  HONO  +  H  J>quil.,  +  - NO,  (82)  IT  2\ + J^O-JTO, H  C H 6  6  +  Ac 0  +  2  NOj  equil. *  2 Ac OH  -SK*-  C  6  H ^  +  H  N0+  (83)  (84)  +  NO2  Under the experimental c o n d i t i o n s the r a t e of n i t r a t i o n was f i r s t order with r e s p e c t t o the n i t r a t i n g substance (84), but was second-order with respect t o n i t r i c a c i d concentration i n agreement With the s e l f — i o n i z a t i o n shown i n 82_ and 85.  JJ  ' HN0 + 3  HN0  3  eqml.„  • ^Q-NO,, +  NO^  (85)  H The  f a c t t h a t the a d d i t i o n  of 0.001 M N a N 0  3  slowed the r a t e of  n i t r a t i o n confirmed that the s e l f - i o n i z a t i o n (85) was an important component of the experimentally observed rate constant.  On the other hand the a d d i t i o n  - 60  of 0,01  -  M s u l f u r i c a c i d introduced a large amount of protons i n t o the system  which dismissed the r a t e determining character of the s e l f i o n i z a t i o n (85)  and  the observed r a t e then became f i r s t - o r d e r with r e s p e c t to n i t r i c a c i d concent r a t i o n (82). The  observation (139) t h a t a c e t o x y l a t i o n occurred as a side r e a c t i o n  i n aromatic n i t r a t i o n (86), (87), (§&) could a l s o be taken as chemical  evidence  f o r the nitronium i o n mechanism. Brown has pointed out (140) t h a t a l l e l e c t r o p h i l i c s u b s t i t u t i o n s ( i n c l u d i n g n i t r a t i o n ) on aromatic n u c l e i proceed by the same general mechanism v i a the formation of charge-transfer complexes. the e l e c t r o p h i l e NO^  According to t h i s model when  approaches the aromatic nucleus, negative charge i s t r a n s -  f e r r e d from the aromatic " TT. - e l e c t r o n cloud" to the p o s i t i v e nitronium i o n (XXVII).  Consequently,  the c l a s s i c a l intermediate or t r a n s i t i o n s t a t e  (84)  (XXVTIl) has to be r e p l a c e d by a s e r i e s of e q u i l i b r i a as shown i n 90, 91  and  92. N0_  i i  Ar N0 +  H  +  NO*  -  +  <L  Ar  H  (90)  2  Ar  -—"  H  +  Ar  N0  (9l)  2  ! H  £+Ar H  N0  2  ^=="  Ar  N0  2  +  BH  +  (92)  :B  In n i t r a t i o n s with n i t r i c a c i d - a c e t i c anhydride mixture the base, sB, corresponds  to NO^  recovered n i t r i c  generated  i n the s e l f - i o n i z a t i o n (85) and EH*" would be the  acid.  The d i s c o v e r y t h a t aromatic C - n i t r a t i o n does not d i f f e r m  principle  from 0- and N - n i t r a t i o n (39) permitted extension of the theory of charge-transfer  -  61  -  O  <o<>»  .H  H C 3  \  (86)  NOo  ( 87)  N 0  2  Ar  XXVII  [XXVIII  Molecule Relative reactivity toward N0 * 2  1 0  1 4  2 4  3 0  - 62 -  complex intermediates  to the formation  of n i t r a t e e s t e r s .  In the l a t t e r case  the oxygen of the a l c o h o l , with l o o s e l y h e l d unshared e l e c t r o n s , played  the  r o l e of e l e c t r o n donor i n the place of the aromatic nucleus i n formation  of  the charge-transfer  complex.  Hughes ( l 4 l ) created r e a c t i o n conditions with respect to NO,  concentration  (high substrate  concentration  by d i l u t i o n with water) i n which the  rates  observed were measures of the r e l a t i v e r e a c t i v i t i e s of C, N and 0 atoms located i n various chemical environments. (89) was  In t h i s manner a s c a l e of r e l a t i v e  reactivities  established. In t h i s research aromatic n i t r a t e e s t e r s were r e q u i r e d f o r photochemical  study and f o r s e v e r a l reasons (as discussed  i n the i n t r o d u c t i o n ) d i r e c t e s t e r i f i —  c a t i o n of the corresponding a l c o h o l s seemed to be the most d e s i r a b l e s y n t h e t i c route.  The  s t r u c t u r e s of the s e l e c t e d aromatic a l c o h o l s were such that  r e l a t i v e l o c a t i o n of the OH group with respect to the aromatic nucleus analogous to t h a t i n benzyl a l c o h o l .  the was  The  synthesis seemed to be f e a s i b l e since  Hughes' f i g u r e s (89) i n d i c a t e d the higher  e f f i c i e n c y of O - n i t r a t i o n compared to  r i n g n i t r a t i o n of benzene.  On the other hand the increased r a t e of n i t r a t i o n  on an a c t i v a t e d aromatic nucleus,  as i n toluene, pointed toward a c l o s e competi-  t i o n between C*- and O - n i t r a t i o n i n the case of the aromatic a l c o h o l s . The  experimental r e s u l t s showed higher y i e l d s of n i t r a t e e s t e r s than  would be p r e d i c t e d from the f o r e g o i n g .  In the case of meso-hydrobenzoin (XXDC)  and dl-hydrobenzoin (XKXl) the amounts of aromatic n i t r o by-products were r e l a t i v e l y small and d i d not cause any d i f f i c u l t y i n the i s o l a t i o n of the pure d i nitrates  ( y i e l d : 57$).  d i t i o n s , the formation and  In the n i t r a t i o n of benzoin (XXXIIl), under s i m i l a r conof yellow G-nitro compounds was  somewhat more pronounced  small amounts of b e n z i l were a l s o i s o l a t e d as the r e s u l t of unwanted  t i o n ; however, the pure n i t r a t e was  still  oxida-  i s o l a t e d i n reasonably good y i e l d  (35$).  - 63 -  In the case of the 1,2-acenaphthenediols (XXXV) (XXXLX) the r e a c t i v i t y of the naphthalene p o r t i o n s of the molecules was much higher than t h a t of the benzene moiety of the hydrobenzoms as p r e d i c t e d from the lower i o n i z a t i o n pot e n t i a l s * and chemical r e a c t i v i t i e s of the corresponding hydrocarbons.  Conse-  co^ be ex pectel t° quently, a number of r i n g n i t r o by-products^originate^i from both the c i s - and t r a n s - d i o l s (96, 9 7 ) . Three d i f f e r e n t compounds (A, B, and C) were i s o l a t e d by chromatography from the crude n i t r a t i o n mixtures from both isomers. Compounds A and'A, were the pure d i n i t r a t e s , while B , B. , C and C, were trans c i s trans cis trans suspected to be r i n g n i t r o by-products.  According to TLC a n a l y s i s (Figure 8)  the compounds i s o l a t e d were chromatographically pure with the exception of B, which contained minor amounts of a second substance, trans Elomontary analyses i n d i c a t e d that r i n g mononitro d i n i t r a t e e s t e r s (Table X I I )  (XXXYII)(XLl) were among the products and t h i s was confirmed by  the i n f r a r e d spectra (Figure 9 ) . The nature of the C f r a c t i o n s remained undetermined although the slow running (low R ^ ) isomer which o r i g i n a t e d from the t r a n s - d i o l was suspected to be nitroacenaphthom infrared  (C-k  r a n s  )  (XLIl) from the elementary a n a l y s i s and  spectrum* Since acenaphthene i s r e a d i l y s u b s t i t u t a b l e by e l e c t r o p h i l i c r e -  agents almost e x c l u s i v e l y at the p e r i - p o s i t i o n s  (143), there could be l i t t l e  doubt about the p o s i t i o n of the r i n g - s u b s t i t u t e d NO^, group. A systematic l i t e r a t u r e survey (27) i n d i c a t e d that the present research (144) was the f i r s t attempted synthesis of aromatic n i t r a t e esters by d i r e c t  esterification.  * The i o n i z a t i o n p o t e n t i a l f o r benzene i s 9.25 ev and f o r naphthalene 8.12 ev (142).  - 64 -  XXXV  XXXVI ( A c s )  XXXVII ( B  N 0 XXXIX  XL  ( A  t  r  a  n  s  )  X L l ( B  t  r  a  C  |  S  )  XXXVIII  NO2  2  n  s  )  XLII(C  t  r  a  n  s  )  (97)  - 65 -  o  O  O O i  _  \is FfGURE from  B  8  cis  TABLE  ^cis  Thin-layer  a s - and  XII  .  Q A  Q  .  trans  Chromatography  B  of  trans  Products  from  Nitration  as-and  ! i  J  ^-trans  trans-1,2-Acenaphthenediols ( M - 3 , S - 1 ,  Nitration  _  i  Products R-1)  trqns-1,2-  Acenaphthenediols.  Product Symbol  Isomer CIS -  ForrnuI a Empirical  Number  0 69  XXXVI  A  /—  trans CIS -  XL  M  12 e°6 2  C  trans CIS —  C trans -  N  H  t_J  /-*  XLI XXXVIII XLII  C  k|  /"\  12 7°8 3  C  H  1 2  N  H 0 N 7  N MP  CC)  129 5-132 5  Obt  0.79  98-100  10.07  0 32  95-98  12.50  0.47  oil  11 81 8 89  0 02  4  0.05  210 - 215  °/o  Calc  10 03  K |  S~\  XXXVII  B  f ( M-3 S-1 R-1 ) R  6.36  10.15  13.10  6.10  -66-  FIGURE  9'  Infrared  Spectra  t r a n s -1, 2 — A c e n a p h t h e n c d i o l .  of  Nitration  Products  of  c j s - and  - 67 -  IIo  Chromatography of N i t r a t e E s t e r s .  I t has been recognized f o r more than a decade ( l 4 5 ) ( l 4 6 ) that hydrogen bonding plays an important  r o l e i n adsorption on s i l i c i c a c i d and t h a t the ad-  s o r p t i o n s i t e s (147) are the weakly a c i d i c hydroxyl groups of the adsorbent. Recently i t was shown (148)(149)(150)(l5l) that the i n f r a r e d absorption band of the surface s i l a n o l group i s s h i f t e d toward lower frequencies upon i n t e r a c t i o n with absorbate m o i e t i e s .  This frequency  shift  ( A ~ J ) i n the adsorption  A  of diethylamme was as large as 73 cm"'' (from 3743 t o 3670 cm''") (152). -  -  Hydrogen  bonding i s a s p e c i a l case of charge—transfer i n t e r a c t i o n s , and i t has been found that the strength of hydrogen bonding ( l . e . A ^ c m "*"), which i s i n f a c t a measure of adsorption, v a r i e s with the i o n i z a t i o n p o t e n t i a l of the adsorbate (152).  This  i  was  experimental  evidence  t h a t the adsorbate molecule i s the e l e c t r o n donor  ( i . e . proton acceptor) and the hydrogen atom of the s i l a n o l group acts as a hydrogen bridge between adsorbent and adsorbate. I t has been c a l c u l a t e d by Sporer and Trueblood distances of hydroxyl groups on adjacent %.  (153) that the 0.....0  s i l i c o n atoms l i e between 4«3 and 5.8  I t was found experimentally by the same authors that the most f a v o r a b l e  " i n t e r - a d s o r b i n g atom d i s t a n c e " (0...0 or 0....N) i n an adsorbed molecule was about 6.1 - 6«2 A" (or a m u l t i p l e of t h a t value) which was close t o the 5.8 i calculated value.  This favoured  i n t e r - n u c l e a r distance was shown t o be a v a i l a b l e  i n meta- and p a r a - s u b s t i t u t e d benzene d e r i v a t i v e s . The  e q u i l i b r i u m constant K f o r the adsorption process  chromatogr'aphed substrate  (S) was determined experimentally  (98) of the  (99) and was  termed  the "adsorption a f f i n i t y " of the substrate. solution  "*  adsorbed  (98)  - 68 -  From equation (lOO) the standard free-energy change f o r the a d s o r p t i o n process was  c a l c u l a t e d and shown t o be dependent on the s t r u c t u r e of the chromato-  graphed s u b s t r a t e *  AF°  =  Furthermore  - RTlnK i t was  (100)  pointed out (153) t h a t there was  "adsorption a f f i n i t y " not only f o r molecules groups (K ) .  (K) but a l s o f o r s u b s t i t u e n t  Thus the value of K f o r a p a r t i c u l a r molecule which c a r r i e d 1  d i f f e r e n t s u b s t i t u e n t s was K  the product of the separate IL values  TT i  K  (101) ( AF°)  of the values of the i n d i v i d u a l s u b s t i t u t i n g groups ( A F ^ ° )  equation  (lOl).  1  and the r e s u l t a n t standard f r e e energy change f o r a molecule sum  a characteristic  was  the  according to  (102)* A  F°  =  £  F °  i  (102)  1  A sequence of group adsorption a f f i n i t i e s  (K ) was  compiled f o r i n -  d i v i d u a l s u b s t i t u e n t s on aromatic n u c l e i i n decreasing order of a d s o r p t i o n affinities  (103).  -CH NH , -COGS, -CB^OH, 4& , 2  7000  2  2  370  260  -COCEj, -OH,  80  70  -CHO,  -N0 ,  23  3.1  27  T h i s sequence explained why  2  -OCHy H  the r i n g n i t r o by-products  (103)  of 1,2-Ace-  naphthenediol d i n i t r a t e s possessed lower R^ values than the u n s u b s t i t u t e d d i n i t r a t e s (Figure 8» Table X I I ) . "In  chromatography the experimentally measurable q u a n t i t i e s are  the d i s t a n c e s t h a t the zone of solute and the f r o n t of solvent have t r a v e l l e d i n the same p e r i o d of time" (153). ment r a t e " , designated R ° , may  The r a t i o of these d i s t a n c e s , the'Vlevelop-  be determined  i n column chromatography when the  - 69 -  concentration i s low enough t h a t the process i s i n the l i n e a r r e g i o n of the Langmuir adsorption isotherm.  In t h i s case K may  perimental R° values according to K  =  be c a l c u l a t e d from the  ex-  (104). 1 - R°  (104)  R° In the more r e c e n t l y developed microadsorption t h i n - l a y e r chromatography  (TLC) the value R ° would be r e p l a c e d by R^ and K i n equation 105  may  be taken as a measure of the adsorption a f f i n i t y . K  =  1 - R„ £_ f  =  (1-1) R  B  (105)  f  S i m i l a r l y the value R ^ (106) which i s a l s o used i n paper chromatography  (154)  would be p r o p o r t i o n a l t o the standard f r e e energy change of a d s o r p t i o n according t o equation  107.  f  AF° =  -2.303 RTRj^  (107)  On t h i s b a s i s the TLC technique should be capable of d i s t i n g u i s h i n g compounds according t o t h e i r f u n c t i o n a l groups.*  I t was  suggested some time  ago i n t h i s l a b o r a t o r y (155) that e l u c i d a t i o n of the molecular s t r u c t u r e of unknown compounds ( p a r t i c u l a r l y t h a t of n i t r a t e e s t e r s ) might be aided by through a comparison of R ^ values determined  TLC  under standardized c o n d i t i o n s and  t h i s p r i n c i p l e has been s u c c e s s f u l l y a p p l i e d i n a q u a l i t a t i v e manner (105), (144). In a q u a n t i t a t i v e study a number of carbohydrate n i t r a t e s and t h e i r parent a l c o h o l s were chromatographed on chromatoplates the experimental  (M—3, S—10.  values together with the c a l c u l a t e d R ^ and  * Phenol protons may process (153)»  R-2)  and  R^-NO,)  c o n t r i b u t e s l i g h t l y t o the t o t a l hydrogen bonding  - 70 -  values f o r r e p r e s e n t a t i v e compounds are summarized i n Table X I I I .  Table X I I I R e l a t i o n s h i p of R^ Values and Structure i n P o l y n i t r o x y Compounds  An  Compound  K-  a ) R  mannitol h e x a n i t r a t e  f  0.747  1  0.339  -0.469  1 mannitol p e n t a n i t r a t e  0.215  3.647  0.562  d u l c i t o l hexanitrate  0.706  0.417  -0.380  0.190  4.272  0.631  0.775  0.291  -0.536  0.044  21.727  1.337  1 d u l c i t o l pentanitrate methyl-]3i-D-glucoside tetranitrate 2 me thy 1 -JS-D-gluc o s i d e — 2,4-dinitrate  -1.031  -1.031  -1.011  -1.011  -1.873  -0.936  average ARj^ per n i t r o x y group  -0.993  a)  D i f f e r e n c e i n number of n i t r o x y groups between corresponding p a i r of c ompounds.  b)  Average of four  c)  from  d)  D i f f e r e n c e of R^ values between corresponding  e)  A R y per n i t r o x y group.  determinations.  (106).  The n e a r l y constant value of A R ^  compounds.  ( v a r i a t i o n about + 5$) f o r the  ^l-NO, group over the range of compounds with v a r i e d s t r u c t u r e s i n d i c a t e d an independent c o n t r i b u t i o n t o the adsorption by each n i t r a t e e s t e r group i n t h i n l a y e r chromatography.  The order of group "adsorption a f f i n i t i e s " c a l c u l a t e d  according to equation 108 from A R ^ K  =  values. 10~  A R  M  (108)  - 71 -  f o r O-substrtuted (RQX) polyhydroxy compounds (where -X may be NC^ or other s u b s t i t u e n t ) determined f o r a s e r i e s of compounds (155) are given i n 109> where the numerical f i g u r e s f o r K -C0CH  3  apply f o r TLC (M-3, S-10, R-2) a t 300°K. >  -N0  2  >  -CH  3  (109) 0.121  0.102  0.076  The remarkable f a c t that i n changing from column chromatography to TLC, and from aromatic C_-substitution t o a l i p h a t i c O - s u b s t i t u t i o n the sequence of a d s o r p t i o n a f f i n i t i e s of the s u b s t i t u e n t s was v i r t u a l l y unchanged (103) from those determined by Sporer and Trueblood (153) made i t evident that TLC r e s u l t s would be j u s t as important i n s t r u c t u r a l elucidations.-ss^^^ffi^p fvrim nib  1 i n iruil im llinili . F i g u r e 10 shows a t y p i c a l chromatographic  R-2) of aromatic and r e p r e s e n t a t i v e non-aromatic  p a t t e r n (TLC, M—3, S - l ,  n i t r a t e e s t e r s and Table  XIV summarizes the observed R^ values (300°K) together with the c a l c u l a t e d constants:  R^, A F ° (the standard f r e e energy change f o r adsorption) and K  (the adsorption a f f i n i t y ) . I t was c l e a r from these data t h a t i f other a c t i v e s u b s t i t u e n t s were a l s o present i n the molecule, such as the two c y c l i c ether oxygen atoms i n (A) or the ketone oxygen i n benzoin n i t r a t e a f f i n i t y toward the adsorbent  (B) the compounds showed increased  (K = 5.54 and 1.98 r e s p e c t i v e l y ) .  A similar e f -  f e c t r e s u l t e d from an accumulated number of n i t r o x y groups i n a molecule as i l l u s t r a t e d by mannitol h e x a n i t r a t e (K = 9.00) ( C ) . In c o n t r a s t , c h o l e s t e r y l nitrate  (D) having p r a c t i c a l l y no other group t o adsorb with other than the  one O-NO,, group had the lowest adsorption a f f i n i t y :  K = 0.258.  Benzylnitrate  (E), a l s o a mononitrate, with the benzene r i n g as a second f u n c t i o n a l  group  f o r hydrogen bonding, showed an a f f i n i t y more than twice as large (K = 0.647)  -72-  08-  06^  04  021  B  D  FIGURE  10  Esters  TLC  &F°  Chromatographic ;  and  i  H  M-3,  S-1,  K values  Pattern  R-2. arc  The  listed  of  Representative  compounds in  Table  and  XIV  Nitrate  calculated  - 73 -  Table XIV Chromatographic Constants f o r N i t r a t e  Compound Name  Formula  R  f  cal^mole  \  A  Isosorbide D i n i t r a t e  XLX  0.151  0.743  B  Benzoin N i t r a t e  XXXIV  0.336  0.296  C  Mannitol Hexanitrate  0.100  0.954  0.258  Esters  K  -rl020  5.54  -463  1.92  -1310  9.00  -0.588  -807  0.258  0.607  -0.189  +259  0.647  1  D  Cholesteryl  E  Benzyl  F  me s o-Hydr obenz o i n Dinitrate  XXX  0.578  -0.137  +188  0.730  dl-Hydrobenz o i n Dinitrate  XXXII  0.560  -0.105  +144  0.786  XXXVI  0.477  0.040  -55  1.10  trans-1,2~Acenaphthene— diol Dinitrate  XL  0.596  -0.169  +232  0.678  trans-1,2-Cyclohexanediol Dinitrate  XXII  0.536  -0.062  +85  0.866  G  H  J  Nitrate  cis-l,2~Acenaphthenediol  I  Nitrate  Dinitrate  See Figure 10,  - 74 -  as that of c h o l e s t e r y l n i t r a t e . meso- and dl-Hydrobenzom d i n i t r a t e s  (P)(G) although dimers of  benzylnitrate d i d not e x h i b i t doubled adsorption a f f i n i t i e s indicating that r o t a t i o n on the C^-C,  (Table XIV")  bond, s t a t i s t i c a l l y d i d not on the  average b r i n g much more than one n i t r o x y group per molecule i n t o contact with the adsorbent. The trans-isomer of 1,2-acenaphthenediol  d i n i t r a t e ( i ) , having a  f i x e d conformation, apparently could be adsorbed by one n i t r a t e e s t e r per molecule, thus the value of K (0.678) was very close t o that of benzyl n i trate (E). affinity  In c o n t r a s t the cis-isomer had almost-twice as large a d s o r p t i o n  (K = l 0 9 6 ) since both of the n i t r o x y groups were s i t u a t e d on the o  same side of the acenaphthene moiety. It was (J)(K  of i n t e r e s t a l s o t h a t the trans-1,2-cyc1ohexandiol d i n i t r a t e  = 0.866) f e l l i n between t r a n s - and cis-l,2-acenaphthenediol d i n i t r a t e s ,  which i n d i c a t e d t h a t the two e q u a t o r i a l n i t r o x y groups were s t e r e o c h e m i c a l l y not as favourably oriented f o r a d s o r p t i o n as were those of the c i s - d i n i t r a t e . This probably meant t h a t the separation of the two n i t r o x y groups i n the t r a n s 1,2-cyclohexandiol d i n i t r a t e was  l a r g e r than t h a t of the two neighbouring  a c t i v e s i t e s (5o8 A*) i n the s i l i c i c a c i d .  They were, however, more s u i t a b l y  oriented f o r absorption than those of the trans-1,2-Acenaphthenediol d i n i t r a t e s . In a d d i t i o n to p r o v i d i n g s t r u c t u r a l information on the pure  sub-  stances TIC was used i n the a n a l y s i s of n i t r a t i o n and other r e a c t i o n mixtures and as a guide f o r developing appropriate column chromatographic (156) f o r the p u r i f i c a t i o n of crude products.  techniques  Furthermore TLC was a l s o i n -  valuable as a technique (157) f o r preparative i s o l a t i o n of compounds on a micro  scale.  - 75 -  III,  A n a l y s i s of Aromatic N i t r a t e E s t e r s .  Elementary  a n a l y s i s c a r r i e d out by the conventional combustion  techniques does not provide s a t i s f a c t o r y r e s u l t s with a l i p h a t i c n i t r a t e e s t e r s (158, 159) due t o i n s u f f i c i e n t combustion and too r a p i d gas e v o l u t i o n . The d i f f i c u l t has been l a r g e l y overcome i n Dumas n i t r o g e n analyses by d i l u t i n g the sample with glucose t o a i d combustion and decrease the r a t e of gas f o r mation.  Table XV Combustion Analyses of P o l y n i t r a t e s  me so-Hvdr obenz o m D i n i t r a t e Element  Content  ($)  Reproducibility  Calcd.  Calcd.  Obsd.  Abs.  Per.  c  55.26  55.43  -0.03  ^0.05$  -0.17  -0.4$  H  3.28  3.87  -0.06  -1.5$  -0.59  -19.7$  N  9.21  9.11  -0.39  -4.3$  -0.10  -1.1$  Abs.  —  Obs. Per.  Mannitol Hexanitrate  N  18.59  18.06  -0.46  In the present work experiments  -2.6  -0.53 -2.9$  were c a r r i e d out t o assess the a c -  curacy of combustion analyses of the c r y s t a l l i n e aromatic n i t r a t e e s t e r s since these had not p r e v i o u s l y been s t u d i e d .  A chromatographically pure sample of  meso-hydrobenzoih d i n i t r a t e was s e l e c t e d as model compound and three p a r a l l e l micro L i e b i g - P r e g l combustions and s i x p a r a l l e l micro Dumas analyses were c a r r i e d out without added glucose.  The average values from these analyses  and the c a l c u l a t e d r e p r o d u c i b i l i t y as w e l l as the d i f f e r e n c e s between the  - 76 -  a n a l y t i c a l values and the t h e o r e t i c a l values are summarized i n Table XV. comparison  For  the n i t r o g e n content of mannitol h e x a n i t r a t e , obtained as an average  from twelve analyses (160) i s a l s o given. It was  apparent from these r e s u l t s that the C$ obtained was  c o n s i s t a n t and a l s o close to the c a l c u l a t e d value, while there was discrepancy i n the H$ v a l u e s .  very  a noticeable  For the N a n a l y s i s the absolute values of both  r e p r o d u c i b i l i t y and d i f f e r e n c e seemed to be b e t t e r f o r the aromatic n i t r a t e e s t e r than f o r mannitol h e x a n i t r a t e . Although the percentage r e p r o d u c i b i l i t y was  somewhat worse f o r the aromatic n i t r a t e  (because of low N content), the  percentage d i f f e r e n c e between the average of the analyses and the c a l c u l a t e d value was almost three times l a r g e r f o r mannitol h e x a n i t r a t e . These r e s u l t s were c o n s i s t e n t w i t h the h i g h carbon content of the hydrobenzoin n i t r a t e i n which the aromatic moiety acted as a " b u i l t nitrogen  i n carbon d i l u e n t " f o r the Dumas  combustion.  IV. A.  Spectra of Aromatic N i t r a t e E s t e r s .  Nuclear Magnetic Resonances Spectra (NMR).  Methyl n i t r a t e  (161) e t h y l n i t r a t e  (162) were the only n i t r a t e e s t e r s  which had p r e v i o u s l y been i n v e s t i g a t e d by proton magnetic resonance s p e c t r o scopy.  In aromatic n i t r a t e e s t e r s , i f the aromatic nucleus can r o t a t e f r e e l y  i n the molecule the resonance of the aromatic hydrogens average out r e s u l t i n g i n a s i n g l e "benzene peak".  T h i s was found to be the case f o r benzyl n i t r a t e .  On the other hand i f the aromatic p o r t i o n c o n s t i t u t e s a r i g i d system the coupling between r i n g protons may  be observable.  T h i s was the s i t u a t i o n i n  the case of the l«2-acenaphthenediol d i n i t r a t e s .  The a n a l y s i s of these and  r e l a t e d r i n g proton s p e c t r a as ABC  systems by the use of ABX  approximation  (163) i s s t i l l i n progress (144) (164) and i s not included h e r e .  - 77 -  Prom the s p e c t r a the g r e a t e s t e f f e c t of the n i t r o x y s u b s t i t u e n t s was r e v e a l e d i n the resonance of the protons i n the  Table  d--positions.  XVI  Group E l e c t r o n e g a t i v i t i e s and f Values f o r c< -Hydrogens  m  N i t r a t e E s t e r s and Related Compounds.  Substituent. Group  -ONO,  -OAe  -OH  -H  Group Elecfcionegati v i t y  3.81°,3.91 2.2i  Hydrocarbon Group  a  3.51  3.83  b  1  Isomer  w  4.18  b  b  d  e H  4.47  C1S-  1,2-Acenaphthenyl"  4.60  4.00  3.46  m-  6.04  4.02  3.97  5.87  3.93  4.05  7.70  5.35  4.90  4.45  8.57  6.17  5.27  4.77  7.60  Benzyl-  9  1,2-Cyc1ohexany1-  trans-  b  3.27  trans-  dl-  Ref. (7),  3.87  6.71  1,2-Diphenylethyl-  a  f  • •  Ref. (162),  In acetone s o l u t i o n 0.2  °  Ref. (161),  d  T h i s work  to 1.0 M, t e t r a m e t h y l s i l a n e = 10.00.  In g l a c i a l a c e t i c a c i d .  Changing the s u b s t i t u e n t s i n the order -H decrease MicroaBO  5  -OH  ,  -OAc  ,  caused est  -ONO,  i n "the  of the a o i d i t i o c  ( l o w o r " v a l u e s ^ of the  A p l o t of the T — v a l u e s of the  ©{-hydrogens  oc-hydrogens  (Table X V I ) .  against the reported  group  -78-  Cyclohexane-,(B)  Benzyl - .(Otrans- and  (D)  cis-12-Acenaphthenyl-  Derivatives  - 7'9 -  electronegativities (7)(162)(Figure 11) revealed that the nitroxy group was apparently much more electronegative than was hitherto reported (I6l)(l62) and i t appeared to be even more electronegative than fluorine (3,93 kcal/mole). From the straight line plots (Figure 11) of the values for the hydrocarbon^alcohols and acetates the extrapolated value of the electronegat i v i t y of the nitroxy group was 4.18 kcal/mole (Table XVII). The meso- and dl-hydrobenzoin derivatives did not give a linear correlation and this was attributed to the f l e x i b i l i t y of the molecular conformations which could therefore be different for each type of derivative. The relative contribution to the shielding of the o. -protons by the hydrocarbon portion of the molecule, was assessed from the intercepts on theaxon of Hie p l o l uud was i n the order cyclohexyl  > benzyl  > aoenaphthenyl  which corresponded exactly to the known order of the positive inductive effect of these groups.  The twidity of the <X -protons i n a given nitrate ester was  -therefore determined by both the nitroxy group and the struoture of the parent hydrocarbon and i t was therefore^that there should be a correlation between T values of the Ci -protons and the reactivity of the nitrate ester with basic reagents. Unfortunately, the available data was rather limited but a plot of the pseudo first-order rate constants for the pyridine reaction of nitrate esters at 25°(62)(63)(144) against the  values of the otprotons (Figure  12) seemed to confirm the predicted result. Obviously more data would be required to test the proposed correlation but some predictions were suggested at this preliminary stage.  It  seemed that compounds which undergo carbonyl elimination with bases were located at the top l e f t of the plot. E _ p  n  Benzyl nitrate which reacted v i a both  and S._. mechanisms (69) would be located somewhere near the f i r s t point  - 80 -  FIGURE the  13  Reaction  Tentative of  C o r r e l a t i o n of  Nitrate  Esters  and  with  Pyridine  A:  cjs-1,2-Accnaphthenedicl  Dinitrate  B  trans-1, 2-Acenaphthcncdiol  C  mesq - Hydrobanzoin  D  d j - Hydrobcnzoi n  E:  Benzyl  F  Isoidide  G  Isosorbide  Dmitrntc  (XIX) (165)  H:  Isomannfdc  Dinitrate  (XX)  I .  t r a n s - 1 , 2 - C v c l o h e x a n e d IQI  J :  Ethyl  (XXXVI)  Dinitrate  Dinitrate Dinitrate  (XL)  (XXIX) (XXXI)  Nitrate Dinitrate  Nitrate  (XVIII) (165) (165) D i n i t r a t e ( XXII)  Mechanism at  25°  in  - 81  of i n f l e x i o n .  Compounds P, G, H,  f l e x i o n i n the curve showed S^. nitrate  ( j)  and  -  I i n the middle and  decomposition (62)  which reacted with bases by both S ^  (56) probably would occupy a p o s i t i o n on the  (63)  at the lower i n and f i n a l l y e t h y l  and E^_^, mechanisms  (55)  lower slope at the r i g h t .  I t i s hoped that t h i s c o r r e l a t i o n i n a r e f i n e d form w i l l serve i n the future as a "diagnostic new  nitrate  diagram" f o r p r e d i c t i n g i o n i c mechanisms of  esters,  B.  Infrared Spectra  (IR).  I n f r a r e d spectra have been reported (166) more than one hundred n i t r a t e esters  (167)  (168)  (169)  for  i n the condensed ( s o l i d or l i q u i d ) s t a t e .  - 82 -  Table XVII Infrared Frequencies of N i t r o x y Groups from Condensed State Spectra  Band  I  Range (cm  )  Assignment s  II  1665-1613  1285-1267  871-833  S> (N0 )  N) (N0 )  V(0N)  a  2  s  2  V  IV  III  759-738  V  N 0  2>  716-685  3  (N0 ) 2  Benzyl N i t r a t e  1626  1278  860  756  me s o-Hydr obenz o i n Dinitrate  1625 1645 1652  1279 1295 1310  842 860  770  (697)* 709  dl-Hydrobenzom Dinitrate  1636 1660  1271  852 867  761  (696)  Benzoin N i t r a t e  1643 1672  1265 1285  840 844  745  (675) (690) (705)  1649 1621  1283  860  754  708  1648 1627  1294 1278 1269  868  758  (728)  trans-1 2Acenaphthenediol Dinitrate p  cis-1,2Ac enaphthe ne d1o1 Dinitrate  697  Values i n parentheses represent bands overlapped by others i n the spectra of the parent a l c o h o l s .  F i v e p r i n c i p a l i n f r a r e d absorption bands were d e f i n e d f o r the n i t r o x y group by Guthrie and Speddmg  (166) as shown i n Table XVII.  The i n f r a r e d ' -  s p e c t r a of the aromatic n i t r a t e e s t e r s synthesized i n the present work were recorded i n the condensed s t a t e .  - 83 -  Table XVIII Infrared Frequencies  of N i t r o x y Groups from S o l u t i o n S p e c t r a * *  I  Band  II  S! (NO,) a <z  Assignment  ^(NO,)  IV  Ill ^(ON)  V °2> N  V 5(NO ) 2  Benzyl N i t r a t e  1637  1276  842  750  6"94  trans-1,2Acenaphthene— diol Dinitrate  1646  1276  843  750  705  1655  1285.  844  cis-1,2-Acenaphthenediol Dinitrate  **  10  (779)*  (726)*  _2 M i n cyclohexane.  as neat l i q u i d s ^ o r as potassium  bromide windows (Table XVII) and a l s o f o r  some of them i n 10 M cyclohexane s o l u t i o n s (Table X V I I I ) . 2  I t was c l e a r from the tabulated data that the m u l t i p l i c i t y of bands i n the s o l i d s t a t e was a f u n c t i o n of the c r y s t a l s t r u c t u r e r a t h e r than of intramolecular i n t e r a c t i o n of v i c i n a l n i t r o x y groups since only s i n g l e t absorptions were observed  i n the s o l u t i o n s p e c t r a .  The s i g n i f i c a n t l y higher frequencies (9 t o 18 cm ^) of the asymmetric and symmetric s t r e t c h i n g frequencies i n the s o l u t i o n spectrum of cis-l,2-acenaphthenediol d i n i t r a t e compared t o those of the trans-isomer and benzyl n i t r a t e has been a t t r i b u t e d t o s t e r i c i n t e r a c t i o n of the contiguous n i t r o x y groups i n the c i s - d i n i t r a t e  (144).  - 84 -  C.  The UV-  U l t r a v i o l e t Spectra  spectrum of 1so-amylnitrate  (UV)  i n ethanol  to that of other a l i p h a t i c mononitrates (95).  I t was  s o l u t i o n was. s i m i l a r  suspected from the spec-  trum that the t a i l on the high wavelength side h i d weak band(s) of unknown origin, as shown i n Figure I t was  13.  reported r e c e n t l y (105)  t h a t the shoulder at 2700 R. was  not  observable i n d m i t r o x y compounds such as isosorbide d i n i t r a t e (XLX) i n d i c a t i n g that upon d i s u b s t i t u t i o n the  "Tr —• ^rr  band became twice as intense as i n the  mononitrates and overshadowed the weak n-.<Tr band.  For t h i s reason mono-  n i t r a t e s were more s u i t a b l e f o r s p e c t r a l study than d i - or p o l y - n i t r a t e s . This absence of f i n e s t r u c t u r e was  also observed i n the case of the aromatic  d i n i t r a t e s (e«g» meso—hydrobenzoin d i n i t r a t e ) and therefore an aromatic monon i t r a t e , benzyl n i t r a t e (23) was  a l s o examined (Figure 14 and  Since aromatic n i t r a t e e s t e r s i n a d d i t i o n to the IT  • "TT  w e l l i t was t i o n was  n—«- iT  and  r  bands of the n i t r o x y group contain the benzenoid absorption not s u r p r i s i n g that the shoulder representing the n — * «T  as  transi-  not as c l e a r as i n the a l i p h a t i c mononitrates. I t was  the n—•'Tr  known from the work of von Halban and Eisenbrand (170)  band i n e t h y l n i t r a t e was  as the n — - T r (172)  15).  that  not subject to as large a solvent e f f e c t  bands of p y r i d i n e N-oxides (171)  or even of carbonyl  groups  (173). An attempt to r e v e a l the n—• Tr r  band by the d i f f e r e n t i a l absorp-  t i o n technique ( t a k i n g the spectrum of benzyl n i t r a t e while benzyl  alcohol  was  failed  i n the blank c e l l i n the same molar concentration  because the e l e c t r o n e g a t i v e  (2x10  M/l))  changed the i n t e n s i t y of the benzenoid  s o r p t i o n band with respect to that i n benzyl a l c o h o l (Figure 14). other hand the d i f f e r e n t i a l spectrum i n higher concentration  (2x10  On _2  abthe  M/l)  - 85 -  FIGURE  13.  Ultraviolet Methanol.  Spectrum  of  iso-Amylnitrate  in  - 86 -  FIGURE 1 4 . Bcnzylnitrate  Bcnzenoid (B)  in  Absorption  Hexane  of  Solution.  Benzylalcohol  (A),  - 87 -  revealed new weak bands a t 200-300 % longer wavelengths which could not be due t o the d i f f e r e n c e m  i n t e n s i t y of the benzenoid absorption  (Figure 15).  S i m i l a r solvent p e r t u r b a t i o n e f f e c t s have been reported f o r carbonyl compounds (173) which were assigned t o hydrogen bonding.  In a l i p h a t i c n i t r o  compounds the t a i l i n g p o r t i o n of the spectrum was found t o be a f e r band due t o a weak charge-transfer P l o t t i n g the frequency  V (cm  complex RCHgNO,  charge-trans-  ..^Solvent  (174).  ) of the two weak bands i n four d i f f e r e n t  solvents (Table X K ) versus the i o n i z a t i o n p o t e n t i a l of the solvents r e vealed i n t e r e s t i n g features of these t r a n s i t i o n s (Figure 16 and 17)• Band I showed a f a i r c o r r e l a t i o n with the solvent i o n i z a t i o n potent i a l i n d i c a t i n g t h a t a t l e a s t t o some extent, t h i s band solute charge—transfer  due t o a s o l v e n t -  i n t e r a c t i o n . T h i s might e x p l a i n the nature of the  t h i r d weak band i n i s o - a m y l n i t r a t e (Figure 13). On the other hand band I I d i d not c o r r e l a t e l i n e a r l y with the i o n i z a t i o n p o t e n t i a l of the solvents but r a t h e r i t l e v e l e d o f f a f t e r an i n i t i a l increase.  No f i r m assignment f o r t h i s band was made but i t seemed  probable t h a t t h i s weak absorption was r e a l l y due t o the molecule and might be due t o an intramolecular i n t e r a c t i o n of groups.  itself  A vapour  spectrum of benzjjnitrate confirmed the existence of another band a t longer wavelength than the n  *u  t r a n s i t i o n but f u r t h e r work would be r e q u i r e d  on t h i s l i n e t o s e t t l e the questions  of assignment.  -  2700 FIGURE  15.  Alcohol  in  D  alcohol  2800  Dif f c r e n c e Various  88  -  2900 Spectrum  Solvents  A  3000 of  310O  Benzyl  benzene,  B  3200  Nitrate ether,  and C  Benzyl  hexane ,  — 89 —  9 (cm ) 1  35,000-  34,000  33,000-  32,0004  CeHg  Et^O  EtOH 10  FIGURE  16. C o r r e l a t i o n the  Solvent  of  eV  11 the  Frequency  Ionization  of  Band  I  with  Potential  v (cm ) | - 1  36,00 0  35,000-^  34,000-^  3 3,000-  10 FIGURE  17. C o r r e l a t i o n the S o l v e n t  11  of  the  Frequency  Ionization  of  Potential.  Band  eV with  - 90  -  Table XIX Solvent E f f e c t s i n D i f f e r e n t i a l Spectra of Benzyl N i t r a t e and Benzyl  Solvent  Ionization Pot. O f v Solvent*'  A  Benzene  B  Ether  C D  Symb  Alcohol  Band I  Band I I  Band I I I  Mi)  Vvcm- )  9.25 )  3010  33,223  2960  33,784  9.53  b)  2950  33,898  2815  35,524  Hexane  10.43°^  2930  34,130  2800  Alcohol  10.50  2920  34,247  2790  b  Vtciif )  1  1  7v(i)  ^(cnf )  2700  37,037  1  35,714  b)  35,842  a) i n eV« b) from R e f . (142) c) from Ref. (13)  V.  P h o t o l y s i s of Aromatic N i t r a t e E s t e r s .  A.  P r e l i m i n a r y Experiments  In general i t was found, that a l l of the aromatic n i t r a t e e s t e r s , synthesized f o r t h i s study, underwent photochemical decomposition upon i r r a d i a t i o n with the f u l l mercury arc spectrum.  In a t y p i c a l experiment a  benzene s o l u t i o n of trans-1,2-acenaphthenediol d i n i t r a t e decomposed r e a d i l y producing  a number of unknown compounds which were separated  t e c t e d as f l u o r e s c e n t spots  by TLC and de-  (Figure 4 8 ) .  I t seemed t o be q u i t e well e s t a b l i s h e d from e a r l i e r studies (104) (105)  that photoreaction r e s u l t e d from the n  e x c i t a t i o n of the n i t r o x y  group and experiments c a r r i e d out i n quartz and Corex c e l l s under a n i t r o g e n  - 91 -  atmosphere (Figure 5 l ) ^ i n a degassed and sealed quartz tube firmed t h i s r e s u l t *  Although the chromatographic  (Figure 49) con-  p a t t e r n was somewhat simpler  f o r the sample i r r a d i a t e d i n the Corex c e l l , the products were g e n e r a l l y the same f o r the three samples i n d i c a t i n g t h a t the longer wavelengths Corex were c h i e f l y r e s p o n s i b l e f o r the p h o t o l y s i s .  passed by  I t was a l s o concluded  from these r e s u l t s that the u n f i l t e r e d mercury arc could be s a f e l y used f o r an ESR study of the p h o t o l y s i s of the n i t r o x y groups since these were the most l i g h t - s e n s i t i v e of the chromophores present. Benzene s o l u t i o n s (l.O ml., 0.01 M) of four secondary aromatic d i n i t r a t e s , one primary aromatic mononitrate nitrate  , and one secondary  alicyclic  (Table XX) were photolysed with the Corex f i l t e r e d mercury arc  (Figure 46.Exp.) and a l i q u o t s were examined a t i n t e r v a l s .  In each case there  was a gradual decrease of the o r i g i n a l n i t r a t e e s t e r c o n c e n t r a t i o n and a gradual accumulation of the p h o t o l y s i s products as i n d i c a t e d by TLC. At the end of 9 hours i r r a d i a t i o n only the s o l u t i o n s from meso—  and d l — h y d r o -  benzoin and i s o s o r b i d e d i n i t r a t e s showed the presence of the o r i g i n a l  nitrate  e s t e r s i n agreement w i t h the r e l a t i v e r a t e s of colour development (Table XX). Chromatographic  a n a l y s i s showed (Figure 18 and F i g u r e 19) t h a t n e i t h e r of the  1,2-diketo compounds, acenaphthenequmone and b e n z i l , were among the yellow products from the acenaphthene and hydrobenzoin  nitrates.  - 92 -  br-a  08  O  O  br-a  0.6  0.4'  0 2 6 Q  f y  B F i g u r e 18.  A. B. Q. C. D. K. E. F.  o  o o o-br  Q y  c  -o—  -O — E  O  yd' £ 31 3  - o  F  Chromatographic Separation of P h o t o l y s i s Products of N i t r a t e E s t e r s (TLC; M-3, S-6).  cis-1,2—Acenaphthenediol D i n i t r a t e trans-1,2-Acenaphthenediol D i n i t r a t e Acenaphthenequmone meso-Hydrobenzom D i n i t r a t e dl-Hydrobenzoin D i n i t r a t e B e n z i l (1,2-Diketo-l,2-diphenylethane) Benzoin n i t r a t e Isosorbide D i n i t r a t e  f: y« o: r: br: br-a: gr-gy:  fluorescence (UV) yellow orange red brown brown absorption (UV) green-gray  - 93 -  A  B  Figure 19.  A. B. Q.  c.  D. K. E. F.  Q_  C  D  K  Chromatographic Separation of P h o t o l y s i s Products E s t e r s (TLC; M-3, S-10).  cis-1,2-Acenaphthenediol Dinitrate trans-1,2-Acenaphthenediol D i n i t r a t e Ac enaphthenequmone me s o-Hydr obenz o m D i n i t r a t e dl-Hydrobenzom D i n i t r a t e Benzil (l,2-Diketo-l,2-diphenylethane) Benzoin n i t r a t e Isosorbide D i n i t r a t e  f:  E of N i t r a t e  fluorescence (UV) yellow y= o: orange r : red br : brown br -a: brown absorption -gy: green-gray  F  - 94 -  Table XX P h o t o l y s i s of N i t r a t e E s t e r s i n Benzene S o l u t i o n s : P r e l i m i n a r y Experiments  I n i t i a l Concentration Comp'd.  Original Nitrate Ester  mg/ml  ONO, grps.  mM/lit.  R e l a t i v e I n t e n s i t y of Yellow Colour After Irradiation  0.5hr.  1.5hr.  9.0hr  A  cis-1,2—Acenaphthenediol Dinitrate  2.7  19.6  i * [ I  iii TTT  iiti TTTT  B  trans-1,2-iAcenaphthenediol Dinitrate  2.9  21.0  -H-  +++  -H-H-  C  me s o-4Iydr obenz oin Dinitrate  3.1  20.4  —  +  +++  D  dl-Hydrobenzoin Dinitrate  3.1  20.4  —  +  +++  E  Benzoin n i t r a t e  2.5  +  -H-  F  Isosorbide D i n i t r a t e *  2.5  —  +  9.7 21.2  ++++ i  -t-H-  1,4|3.6-dianhydro-D-glucitol-2,5-dinitrate.  The a l i c y l i c secondary n i t r a t e e s t e r (F) showed much the same p a t t e r n of products as was obtained with the four aromatic v i c i n a l d i n i t r a t e s ,  indicating  t h a t the nature of the R- group i n the e s t e r s RONO, was not c r i t i c a l i n d e t e r mining the course of the r e a c t i o n . Although care was taken i n these experiments t o exclude atmospheric oxygen, i n order t o prove t h a t the yellow products formed during the p h o t o l y s i s i n benzene d i d not o r i g i n a t e from o x i d a t i o n due t o the presence of d i s s o l v e d oxygen or water, a s i m i l a r experiment was conducted i n degassed and sealed quartz tubes i n c a r e f u l l y p u r i f i e d benzene.  The quartz tubes were opened  and i n the moment when the tube was cracked, the c o l o u r l e s s gas i n the tubes  - 95  -  became yellow—brown i n d i c a t i n g t h a t a gaseous product of p h o t o l y s i s was which immediately  o x i d i z e d t o N0  2  on the admission of oxygen.  NO  Qualitative  observations f o r the r e a c t i o n s are summarized i n Table XXI. The p a t t e r n obtained by TLC agreed with the r e s u l t s of the previous experiment.  The use of a l k a l i n e permanganate spray reagent  the pronounced yellow spots resembled presence  of ortbo-nitrophenol was  (R—3) showed t h a t  phenols i n ease of o x i d a t i o n and the  confirmed by comparison with a r e f e r e n c e  sample on the chromatogram (Figure 20), by the s i m i l a r response t o spray reagent R-3  and a l s o by the f a c t t h a t the yellow colour faded at the same  r a t e on the chromato—plates  upon standing while other coloured spots were  permanent f o r s e v e r a l weeks.  Table  XXI  P h o t o l y s i s of N i t r a t e E s t e r s i n Oxygen-free Absolute Benzene S o l u t i o n s  I n i t i a l Cone. Symbol  After Irradiation f o r 22 h r s .  Name Comp/d ONO,,  Original Nitrate Ester  mg/ml  grps. R e l a t i v e R e l a t i v e R e l a t i v e Colour Amount Amount of of P r e of mM/lit S o l u t i o n c l p i t a t e NO gas  cis-1,2—Acenaphthenediol Dinitrate  26.9  195  ++  +++  trans-l*2-Acenaphthenediol Dinitrate  27.7  200  ++  +++  +++  Dinitrate  30.0  197  ++  ++  ++  dl-Hydrobenzom Dinitrate  30.4  200  ++  ++  ++  E  Benzoin N i t r a t e  25.8  101  +++  —  —  F  Isosorbide D i n i t r a t e *  23.4  198  +  +  +  A B C  D  meso-Hydrobenzoin  1,4j3,6-dianhydro-D-glucitol-2,5-dinitrate  - 96 -  y  y\—^  V  .0 O 9 01-  ,o  , 0  A  B  FIGURE  20  Photolysis A diol E  C  D  Chromatographic Products  of  Benzoin  phenol;  meso —  Nitrate,  F  )  after  before spraying  D  B  }  dl - Hydrobenzoin  y  yellow  spraying, white with  S-1,  R-3)  t r a n s - ^ 2 - Acenaphthene  Isosorbidedmitratc  f : fluorescence ( U V )  * : colourless ground  C  ( M-3,  G  Esters  Dinitrate;  1  Dinitrate,  Separation  Nitrate  cis -1 2 - A c e n a p h t h e n c d i ol  F  E  R-3  }  spot  Dinitrate, G  b> cn  orifo-NitroK  brown pink  ;  back-  - 97  -  The same y e l l o w photo-products were detected i n the case of benzoin n i t r a t e but i n a d d i t i o n other c o l o u r l e s s spots, not present among the products o r i g i n a t i n g from the other n i t r a t e e s t e r s showed up a f t e r spraying with reagent R-3.  Other d i f f e r e n c e s i n the products from benzoin n i t r a t e  (an  c*- -keto  n i t r a t e e s t e r ) and the other n i t r a t e e s t e r s are shown i n Table XXI»  B.  I d e n t i f i c a t i o n of P h o t o l y s i s Products.  The p r e l i m i n a r y experiments showed t h a t j w i i t r o p h e n o l and probably other n i t r o p h e n o l s were formed from the solvent benzene.  T h i s consecutive (or  simultaneous) o x i d a t i o n and n i t r a t i o n of the benzene r i n g could have taken place only at the expense of the n i t r a t e e s t e r s since no other oxygen and n i t r o g e n source was  a v a i l a b l e i n the system.  T h i s observation made i t evident  t h a t care had to be  taken to d i s t i n g u i s h between products o r i g i n a t i n g from the  solvent and those o r i g i n a t i n g from the n i t r a t e e s t e r i n the p h o t o l y s i s , meso-Hydrobenzoin d i n i t r a t e was t h e r e f o r e i r r a d i a t e d i n t h i r t e e n d i f f e r e n t s o l v e n t s * on a micro scale to o b t a i n p r e l i m i n a r y i n f o r m a t i o n and then i n three solvents} benzene, ether, and a l c o h o l f o r more d e t a i l e d  inves-  tigation. (1)  Products from Solvents I r r a d i a t i o n i n Benzene S o l u t i o n s Benzene s o l u t i o n s of nieso—hydrobenzoin d i n i t r a t e  radiated m  the photoreactor (Figure 47)  v a r i o u s lengths of time, mixtures by  w i t h Corex f i l t e r  ji-Nitrophenol was  (0,01  M) waSh" i r -  (Figure 46)  for  i s o l a t e d from the i r r a d i a t i o n  vacuum and steam d i s t i l l a t i o n s and i t s i d e n t i t y was  confirmed  Diethylamine, ethanol, ethylmercaptan, dioxane, cyclohexane, c y c l o -  hexane, benzene, carboi (titBulf ide, a c e t i c a c i d , ethyl.*|cetate, d i e t h y l e t h e r , a c e t a l , and phenol.  -98  -  by i t s n i t r o g e n content and by t h i n l a y e r chromatography.  For i s o l a t i o n and  i d e n t i f i c a t i o n of the other yellow p h o t o l y s i s products, the unreacted n i t r a t e e s t e r and the j3-nitrophenol were removed by column chromatography and the r e s u l t i n g mixture was  analyzed by TLC as shown i n Figure 21 (A-P)  for various  times of i r r a d i a t i o n . I t was  evident t h a t not a l l of the coloured spots o r i g i n a t e d from  the primary i n t e r a c t i o n of n i t r a t e e s t e r s and benzene since the p a t t e r n changed with the time of i r r a d i a t i o n .  C e r t a i n spots (G and J) appeared  early  (0.5 hrs.) and t h e i r c o n c e n t r a t i o n a f t e r reaching a maximum value g r a d u a l l y decreased with.time*  Other spots (D, H, L, M, and 0) were not d e t e c t a b l e  i n the e a r l y stages of the i r r a d i a t i o n and some of them s t a r t e d to appear a f t e r 5 or even 10 hours, i n d i c a t i n g t h a t they e i t h e r accumulated  by a very  slow process which d i d not dominate over the main course of the r e a c t i o n or that they were secondary products o r i g i n a t i n g from the n i t r o compounds formed i n the primary process. Because of the s i m i l a r i t i e s i n R^ values, column  chromatographic  s e p a r a t i o n under s i m i l a r c o n d i t i o n s f a i l e d completely (156) and t h i c k - l a y e r microadsorption chromatography (105) results.  Repeated TLC was  ( 208) also d i d not provide s a t i s f a c t o r y  used s u c c e s s f u l l y f o r separating these products  but because of the micro scale of the method and the large number of components,  only the compounds which occurred i n r e l a t i v e l y high c o n c e n t r a t i o n  were i s o l a t e d on a m i l l i g r a m s c a l e . F i g u r e 22 shows a chromatogram of ten pure compounds i s o l a t e d from the photoreaction products.  Comparison with known compounds i n d i c a t e d that  E might be 2,4-dinitrophenol, while G agreed very w e l l with and F was  s i m i l a r t o 2,6-dinitro-4=phenylphenol.  and D (Figure 23) i n d i c a t e d the presence  2,6-dmitrophenol  The i n f r a r e d s p e c t r a of C  of n i t r o x y groups as w e l l as aromatic  n i t r o groups i n a s t r u c t u r e s i m i l a r t o that of meso-hydrobenzoin d i n i t r a t e .  - 99 -  FIGURE  21  Photolysis Solution  Chromatographic of  (M-3j  Separation  meso —Hydrcbenzoin  of  Products  Dinitrate  S-5 )  t  f. o-br  fluorescence orange  (UV)  brown;  y  yellow,  brown = br.  o  orange ,  in  from  Benzene  — 100 —  f  fluorescence  o-br  orange  ( UV); brown,  y  yellow;  b  brown  o  orange ,  - 101  -  Since no unreacted meso-hydrobenzom d i n i t r a t e was  present,  these compounds  were i d e n t i f i e d as r i n g - n i t r a t e d meso-hydrobenzoin d e r i v a t i v e s (Figure Although C showed a broad OH band at 3400 cm  1  t h i s was  p o s s i b l y due  23).  to  moisture smoo the parent meso-hydr obenzo i n e x h i b i t e d a sharp OH peak. b a s i s that R ^ ( C ) ^ R^(D) (Figure 21)  i t was  and t h a t D showed up l a t e r than C i n the  suspected that C was  n i t r o meso-hydrobenzom d i n i t r a t e .  E',  re-arrangement.  i n f r a r e d spectrum of E, the petroleum ether s o l u b l e p o r t i o n of  r e g i o n so t h a t there was  no doubt that E was  r e s u l t s , however, there were two  of E at 2900 and  1726  cm  1  even i n the f i n g e r p r i n t  2,4-dinitrophenol  were probably isomeric  i n agreement  a d d i t i o n a l peaks i n the  i n d i c a t i n g t h a t some E  1  spectrum  contaminated the  E' and E " gave d i s t i n c t i v e although q u i t e s i m i l a r s p e c t r a  The  photoreaction  These compounds would be the products of  (Figure 24) matched t h a t of 2,4-dinitrophenol  w i t h TLC  sample.  (Figure 24)  i n f r a r e d s p e c t r a of F, K,  s i b l e i n these cases*  and  and  dinitrophenols. and N were compared to t h a t of  2 , 6 - d m i t r 0—4—phenyl phenol (Figure 25) but no f i r m i d e n t i f i c a t i o n was  occurred  the  the 4-mononitro- and D the 4,4' - d i -  intermolecular n i t r a t i o n rather than of intramolecular The  On  However, the f a c t that orange spots  pos-  s i m i l a r to F  a l s o among the p h o t o l y s i s products from dl-hydrobenzoin d i n i t r a t e  from benzyl n i t r a t e but were completely absent i n the i r r a d i a t i o n mix-  tures from c i s — and trans-1,2-acenaphthenediol d i n i t r a t e s suggested t h a t t h i s compound o r i g i n a t e d i n the n i t r a t e e s t e r s r a t h e r than i n the s o l v e n t .  On  the  other hand i f F were r e a l l y 2,6-dinitro-4-phenylphenol t h a t would mean t h a t phenyl r a d i c a l s were generated with three tacked The  the simultaneously  out of f i v e n i t r a t e e s t e r s and  formed n i t r o p h e n o l s  as represented  suspected r e a c t i o n would be somewhat analogous to one  P r i c e and Convery (175)  f o r meta-dinitrobenzene.  i n equation  (ill)  reported  at110. by  FIGURE  23  Nitrobenzene  Infrared (B)  and  Spectra  of  Photolysis  mcso-Hydrobenzoin Products  of  A  (C  Dinitrate and  D)  (A)  — 103 1  1  1  r  1—  1  1  r~  1  p-  ^C-NO  A  ^ /  i  \ A  i  i  .  i  AA  1  i  'i  •t  1  r  1  i  1  '  2  A i  1  1  t 1  1  1  i  i  1_  1  1  1  1  1  i  i  1  1  ,  ,  1  1  E'  i  i  1  ,  1 1  1  3000 FIGURE Products  1  1 2000  24  1  Spectra  from  1  .....  1800 (IR)  1  of  1  1600  1  1  1  i  1 l  1 1400  '  2,4-Dinitrophenol  meso-Hydrobenzoin  1  1  1 4000  i  Dinitrate  I  I  1200 (A)  I  Tooo""  and  (E,E'and  1 1 , 8 0 0 cm"  Photolysis E" )  1  - 104 —  3500  2500 FIGURE and (F,  25  1900 Infrared  Photolytic K and  N )  1700 Spectra  Products  1500 of  from  1300  1100  90O  2,6-D.mtro-4-Phenylphenol rneso-riydrobcnzoin  700 (A)  D,n,trat<  cm-  1  - 105  -  I r r a d i a t i o n i n Ether S o l u t i o n , No product which o r i g i n a t e d s o l e l y from the solvent was  isolated  i n the i r r a d i a t i o n of meso-hydrobenzoin d i n i t r a t e i n ether s o l u t i o n , spot i n the chromatogram was was  A major  l o c a t e d ahove the unreacted n i t r a t e e s t e r which  q u i t e unusual since i n most cases the n i t r a t e e s t e r possessed a higher  R^ value than any of the p h o t o l y s i s products. of t h i s compound was  The c h a r a c t e r i s t i c f e a t u r e  i t s b r i g h t fluorescence under u l t r a v i o l e t l i g h t  and  upon spraying the chromatogram with concentrated n i t r i c a c i d - s u l f u r i c a c i d mixture  (R-l) the spot turned green immediately.  Only solvents which pos-  sessed the s t r u c t u r e X—0—Y, i . e . d i e t h y l e t h e r , e t h y l acetate, a c e t a l , dioxane, produced t h i s or s i m i l a r compound. compound was  and  From the high R^ value the  suspected to be the k e t a l of the corresponding diketone  (benzil),  however, a c i d c a t a l y s e d h y d r o l y s i s of the i s o l a t e d c r y s t a l l i n e compound (m.p.  95-98°) f a i l e d to y i e l d b e n z i l .  The NMR  spectrum of the sample  was  recorded and there seemed to be l i t t l e doubt t h a t some s o r t of a l k y l a t i o n had taken place on the parent molecule vent molecule was  (Figure 26), i n other words the  sol-  incorporated ( i n part or i n f u l l ) i n t o the meso-hydroben-  z o i n moiety, however, f u r t h e r work would be r e q u i r e d to e l u c i d a t e the  struc-  ture of t h i s unknown product.  Irradiation i n Alcohol Solutions Acetaldehyde  was  i s o l a t e d as the 2,4-dmitrophenylhydrazone from  i r r a d i a t i o n of ethanol s o l u t i o n s of the n i t r a t e s .  The  same product was  ob-  t a i n e d by i r r a d i a t i n g e i t h e r me s o-hydr obenz o i n d i n i t r a t e or benzyl, n i t r a t e under s i m i l a r c o n d i t i o n s .  The 2,4-dmitrophenylhydrazone was  i t s melting pointy elementary  i d e n t i f i e d by  a n a l y s i s , t h i n l a y e r chromatography and nuclear  magnetic resonance spectrum. This o x i d a t i o n of a l c o h o l to aldehyde during the  photo—reduction  -106 -  H  -i  L  V  L  -1  L  JLJL  L.  -1  _J  !_,  l_  L  -\  B  J  80  ,  1  1  70 450  __i  FIGURE A  B  ,  -J  l_  60 400 26  5.0  350 NMR  40 250  300  Spectra  of  meso-Hydrobcnzom,  B  Irradiated  Solution  in  Ether  -J  , l_  30 200  10  20 150  1, 2 - D i p h e n y l e t h a n e  meso-Hydrobenzoin  l_  L  50  100  Derivatives  Dinitrate,  C  p p m (h) 0  Product  0 cps from  - 107 -  of n i t r a t e esters seemed t o be analogous t o the o x i d a t i o n of benzene t o phenol. (11)  Products from I r r a d i a t e d N i t r a t e E s t e r s . The  n i t r a t e e s t e r s during p h o t o l y s i s s p l i t up to fragments, the  nitrogen-oxygen p o r t i o n reacted with the solvent or a c t i v e solute but gaseous nitrogetvoxides were a l s o detected.  Semi-quantitative  mass s p e c t r a l a n a l y s i s  i n d i c a t e d a r a t i o of 4 0 s i f o r NOtNO, i n a gas mixture which was a blue s o l i d when trapped a t 77°K. S k e l e t a l fragments of the n i t r a t e e s t e r s were a l s o i s o l a t e d and i d e n t i f i e d i n most cases. Irradiation  of 1,2-Acenaphthenediol D i n i t r a t e s .  Both c i s — and trans-1,2—acenaphthenediol d i n i t r a t e s i r r a d i a t e d i n benzene s o l u t i o n y i e l d e d , i n a d d i t i o n t o some u n i d e n t i f i e d f l u o r e s c e n t of low  spots  values, naphthalene—1,8-dialdehyde which was i s o l a t e d and i d e n t i f i e d  both as the 4-nitrophenylhydrazone and i n the o x i d i z e d form as napfo.thalene-1, 8-dicarboxylic  acid.  Thus the main course of the p h o t o l y s i s seemed t o proceed  to equations 112 and 113. On the other hand i t was l i k e l y t h a t _o-nitrophenol  was not formed  i n one simple step but that the n i t r a t i o n was preceded by the o x i d a t i o n of the aromatic r i n g .  This production  of the intermediate  the cost of the simultaneous r e d u c t i o n  phenol occurred at  of n i t r a t e e s t e r t o n i t r i t e  ester  which i n t u r n photolysed t o a l k o x y l r a d i c a l and NO a t the longer wavelengths. The  s p l i t t i n g of the carbon-carbon bond between adjacent n i t r a t e  e s t e r groups (112 and 113) has a l s o been observed (74) m of 2,3-dinitroxy-butane  (47) as discussed  the thermolysis  i n the i n t r o d u c t i o n .  The s i m i -  l a r i t y of the r e a c t i o n i n the p h o t o l y s i s of v i c i n a l d i n i t r a t e s was e x p e r i mental evidence t h a t i n the s o l u t i o n p h o t o l y s i s of n i t r a t e e s t e r s j u s t as  - 108 -  - -109  i n thermolytic  -  r e a c t i o n s a l k o x y l r a d i c a l s play a v i t a l r o l e as  intermediates.  I r r a d i a t i o n of Benzyl N i t r a t e P h o t o l y s i s of benzyl n i t r a t e i n both benzene and a l c o h o l s o l u t i o n s gave r i s e to the same products o r i g i n a t i n g from the solvents, namely n i t r o — phenols from benzene and  acetaldehyde from a l c o h o l , as were found w i t h the  hydrobenzoin d i n i t r a t e s . Consequently, there can be no doubt t h a t the f r a g mentation p a t t e r n of the n i t r o x y group was  the same f o r t h i s primary mono-  n i t r a t e as f o r the secondary d i n i t r a t e s , i n other words i t was of the n i t r o x y group and molecule.  The  a function  independent of the s t r u c t u r e of the r e s t of the  intermediate  a l k o x y l r a d i c a l probably underwent one  of the f o l l o w i n g r e a c t i o n s as described  i n recent reviews (91)  1.  Intermolecular  hydrogen a b s t r a c t i o n  2.  Disproportionation  3.  R a d i c a l e l i m i n a t i o n , which could have occurred  or more  (70):  (114) (115) i n two d i f f e r e n t  ways. (a)  The  e l i m i n a t i o n of the  ( e n e r g e t i c a l l y unfavourable) (70) (b) The  (70)  (116)  (176).  Carbon-carbon s c i s s i o n  carbon-carbon cleavage i n benzyloxyl  ported  -hydrogen  (117)  r a d i c a l has not been p r e v i o u s l y r e -  (l77)» however, t e r t i a r y a l k o x y l r a d i c a l transformation  with  simul-  taneous generation  of phenyl r a d i c a l and the corresponding ketone(118) has been  established  The  (70),  generation  of phenyl r a d i c a l s would a l s o be  with the formation of biphenyl d e r i v a t i v e s  consistent  (110).  I r r a d i a t i o n of meso-Hydrobenzom D i n i t r a t e . The  two  isomeric hydrobenzoin d i n i t r a t e s behaved s i m i l a r l y to the  acenaphthenediol d i n i t r a t e s i n that C-C  bond s c i s s i o n occurred  between the  -  110  -  - Ill -  two  v i c i n a l n i t r o x y groups to produce aldehydes.  o r i g i n a l molecule was  s p l i t i n t o halves i t gave r i s e to two moles of  dehyde per mole of n i t r a t e e s t e r . over a r a l k y l C~C  Since i n t h i s case the  This r e a c t i o n (119)  seemed to be  benzalpreferred  bond s c i s s i o n (120), however, both could have taken place  simultaneously. The  benzaldehyde o r i g i n a t e d from meso-hydrobenzoin d i n i t r a t e upon  i r r a d i a t i o n i n both benzene and ethanol  s o l u t i o n s and was  c h a r a c t e r i z e d as the 2,4-dmitrophenylhydrazone.  i s o l a t e d and  A p o s s i b l e mechanism f o r  the photo-decomposition of meso-hydrobenzom d i n i t r a t e i s given i n Figure Since i n the p r e l i m i n a r y was  i n v e s t i g a t i o n of solvent e f f e c t s , phenol  found to be very r e a c t i v e with excited n i t r a t e esters  the sample turned brown w i t h i n minutes) i t was state concentration was  27.  (upon i r r a d i a t i o n  not s u r p r i s i n g t h a t the  of phenol could not be detected.  steady  On the other hand i t  a l s o p o s s i b l e t h a t the phenol remained t i e d up to the decomposing n i t r a t e  e s t e r molecule i n a complex u n t i l i t was  s u b s t i t u t e d by the N0  2  group i n i t s  orjfb-position. In the generation  of d m i t r o p h e n o l s from _o-nitrophenol  by the  con-  sumption of a second mole of n i t r a t e e s t e r , the p r e f e r e n t i a l s u b s t i t u t i o n f o r the entering N0  2  group was  l i k e l y t o be on carbon 4, however, s u b s t i t u t i o n on  p o s i t i o n 6 a l s o occurred  but seemed to be somewhat l e s s extensive  from the chromatograms.  Other a c t i v a t e d benzene r i n g s i n unreacted meso-  hydrobenzoin d i n i t r a t e may  a l s o have acted as N0  2  acceptors as was  as judged  discussed  above. By comparison with previous work on the p h o t o n i t r a t i o n of d i phenylamme (105) matic system was  i t seemed t h a t r i n g p h o t o n i t r a t i o n occurred when the a c t i v a t e d by appropriate  substituents, but with only  aronon-  a c t i v a t e d benzene r i n g s present o x i d a t i o n seemed to be the p r e f e r r e d r e a c t i o n .  — 112 —  0 N0  Ph  2  Ph  hv,  /  C-  \)N0  0 NO 2  C-H V 'O  y C-  Ph  2  Ph  /  v  hv. 0 NO 2  o  Ph  H^lC-  C-  V •H  / Ph  +  NO  O.  0,NO  C / Ph  OH S  [»•]  ,N0  PhCHO  PhCHO  2  Ph  I 0 MO 2  P  0 NO  n  H  O-N \\ O  Ph  Ph  2  hv-  S c  C  Ph ;  [HC]  MO  O.  J  0 NQ 2  I  +  I  H.  +  PhCHO  Ph  H 0 2  OH  [«•]  FIGURE  •O  NOn N0  27  Possible Dinitrate  PhCHO Ph  0  Mechanism  of  Photolysis  of  me s o - H y d r o b e n z o i n  - 113  The  -  f a c t t h a t i n the Kemula-Grabowska r e a c t i o n (67)  (113)  of benzene by means of NO a l s o produced _o-nitrophenol provided  the  and  photonitration  2,4-dinitrophenol  a clue f o r the e l u c i d a t i o n of the mechanism of the present  which w i l l be discussed  reaction  i n a later section.  C.  K i n e t i c Study of the P h o t o l y s i s .  F i v e aromatic n i t r a t e esters were subjected to k i n e t i c measurements.  Three of the f i v e  n i t r a t e s ) contained  (benzyl n i t r a t e , meso- and dl-hydrobenzom d i -  benzene r i n g s while the remaining two  acenaphthenediol d i n i t r a t e ) A Corex f i l t e r was  used i n a l l k i n e t i c experiments i n order to e l i m i -  the t a i l of the n i t r a t e e s t e r spectrum was  the  —" \C r  group and  trans-1,2-  had naphthalene n u c l e i i n t h e i r molecules.  nate the short wavelength l i n e s of the mercury a r c .  t i o n of the NO,  ( c i s — and  In these c o n d i t i o n s  involved p r o v i d i n g n -J^  only  excita-  only n e g l i g i b l e numbers of quanta were s u p p l i e d to  bands of both n i t r a t e ester and benzene n u c l e i .  This p r a c t i c a l l y  s e l e c t i v e e x c i t a t i o n gave a reasonably c l e a r p i c t u r e of the photodecomposition of these n i t r a t e e s t e r s bearing benzene r i n g s i n t h e i r molecules. In the case of the d i n i t r a t e s of c i s - and t h i s s e l e c t i v e e x c i t a t i o n was the molecule has  trans-1,2-acenaphthenediol  not p o s s i b l e because the naphthalene p o r t i o n of  an e x t i n c t i o n c o e f f i c i e n t about 100 times l a r g e r than t h a t  of the two n i t r o x y substituents at the same wavelengths and the weak (£.**=  25/nitroxy  group)  n  —» tC f  absorption.  expected that acenaphthene d e r i v a t i v e s would photolyse  i t over powered  On t h i s b a s i s i t was considerably more slowly  than the benzene d e r i v a t i v e s . The r a t e measurements were based on the r a t e of disappearance of nitrate esters.  Since not a l l of the n i t r a t e e s t e r molecules which reached  the e x c i t e d state decomposed (because a c e r t a i n f r a c t i o n of them became deactivated)  the rate of decomposition should be slower than the r a t e of  - 114  light  -  absorption. I t i s g e n e r a l l y accepted t h a t t r i p l e t s t a t e s are involved i n photo-  chemical processes,  and that t r i p l e t e x c i t e d s t a t e s always have longer  times than s i n g l e t e x c i t e d states because of t h e i r lower oncrgioo. i l l u s t r a t e s these p r i n c i p l e s of primary photoreactions n i t r a t e esters (NE).  (178)  life-  Figure  28  a p p l i e d to the  Whether the r a d i a t i v e d e a c t i v a t i o n processes ( f l u o r e s -  cence and phosphorescence) l a b e l l e d k ^ vable experimentally  and k ^ *  would be a c t u a l l y obser-  i n the case of n i t r a t e e s t e r s was  not known but i t  seemed reasonable t o assume that they a l s o occurred here as they do i n many other  reactions* Reaction k^ was  responsible f o r e x c i t a t i o n and assuming 100$  ef-  f i c i e n c y , the same number of molecules became e x c i t e d as the number of photons absorbed by the n i t r o x y group. by three r o u t e s , two resented route  The  Of which (K ^  t o t a l energy absorbed was and k ^ )  then d i s s i p a t e d  were d e a c t i v a t i o n s and thus rep-  l o s s of energy as f a r as p h o t o l y s i s was  concerned, only the  third  ( l ^ ) l e d t o the decomposition of n i t r a t e e s t e r molecules forming the  r e a c t i o n products.  The quantum y i e l d  ( l 2 l ) r e l a t e d the decomposition (k,) to  the t o t a l e x c i t a t i o n (k^) assuming t h a t one photon e x c i t e d one molecule.  0 =  A [.NE] decomposed A  If there was  [NE]excited  no chain r e a c t i o n and only one photon was  the photoreaction  required for  causing  of one molecule, 0 would have a value between 0 and 1,  the d e a c t i v a t i o n process was  d e a c t i v a t i o n process,  0  If  n e g l i g i b l e with respect to decomposition then  0 — » - l , i f the r a t e of decomposition (k^) was  It was  (121)  exceeded by the r a t e of the  »-0.  found that at i n i t i a l concentrations  of l e s s than 0.1  of n i t r o x y group per l i t e r the e a r l y part of the photoreaction  followed  mole a  1  NE*  r a d i ationless transition  fluorescence  3  <1 excitation  NE*  * -13 phosphorescence  NE,  products  FIGURE  28  Primary Nitrate  Photochemical Esters  tNE)  Reactions  of  -  116  -  f i r s t - o r d e r r a t e law as shown i n Figures 29 and 31.  Since the products  (nitrophenols, etc.) a l s o absorbed i n the e f f e c t i v e wavelength r e g i o n , on more extended i r r a d i a t i o n even with low i n i t i a l concentrations  (0.02 M), the  r e a c t i o n slowed down as observed i n the r a t e p l o t ( l o g concentration time) by the departure from the s t r a i g h t l i n e  versus  (Figure 2 9 ) . This e f f e c t was  p a r t i c u l a r l y pronounced with the acenaphthene n i t r a t e s because the products c o n t a i n i n g the naphthalene nucleus absorbed s t r o n g l y i n the a c t i v e r e g i o n . Equation 122 described the amount of l i g h t absorbed (I ) A respect t o the i n c i d e n t i n t e n s i t y ( l )  as a f u n c t i o n of the o p t i c a l  Q  density  (O.D.).  I. A  If 0 . D . » 1 then the exponential  =  I  (l-e°' ')  (122)  D  O  term would be n e g l i g i b l e and I —»• I  i f , however, 0 . D . « 1 then 1 ^ — I  x O.D. since the exponential  be approximated by the f i r s t two members of a T a y l o r s e r i e s . c o n d i t i o n was s a t i s f i e d by the low i n i t i a l concentration On the other hand at the low concentration and  O.D. could be replaced by  with  ,  term would  This second  of the n i t r a t e e s t e r .  the Lambert-Beer law was a l s o v a l i d  [NE]to give equation 123. I. A  -  I £ t  o  [NE| »•  (123) — ™  Since the t o t a l O.D. or t o t a l £ was the sum of the values f o r the s e v e r a l components of the system, equation 123 could be used t o c a l c u l a t e the l i g h t absorption  f o r a p a r t i c u l a r mode of e x c i t a t i o n .  n  band of the n i t r a t e e s t e r , the c a l c u l a t e d 1^  •IT  represented number of  Substituting  f o r the  (einstein/sec)  the number of e x c i t a t i o n s , which i n t u r n was a measure of the  n—- uT c  e x c i t e d s t a t e s (moles/sec) generated during the i r r a d i a t i o n .  Since the r a t e of decomposition was p r o p o r t i o n a l t o the number of quanta absorbed per u n i t time, 1^,  according  t o 123, the r a t e of decomposition was  a l s o p r o p o r t i o n a l t o the concentration  of the n i t r a t e e s t e r and t h i s was the  °  2  4  G  8  I r r a d i a t i o n T i m e in F I G U R E 29  R a t e s of P h o t o r e a c t i o n  Hydrobenzoin  Dinitrates,  nitrates  Benzene  in  of ( A )  ( D) t r a n s - and  Solution  at  25°  (E)  10  12  14  Hours  B e n z y l N i t r a t e , (B) dl- a n d cis-1 2 - A c c n a p h t h c n e d i o l  (C)mesoDi-  - US -  o r i g i n of the observed f i r s t - o r d e r r a t e law. In the p h o t o r e a c t o r ^ the s o l u t i o n thickness was 0.665 cm. ^there-> fore 1^ f o r one p a r t i c u l a r wavelength  ij A  ( /\ ) was given by 124.  =  0.665 I £ [NB] o  (124)  7 1  L  J  In t h i s i n v e s t i g a t i o n not monochromatic l i g h t but a p o r t i o n of the spectrum of the mercury a r c (Figure 33) was employed  and t h e r e f o r e the above  equation was used f o r each of the a c t i v e wavelengths and the values of 1^ were summed up f o r estimating the t o t a l number of quanta/sec absorbed (125).  I*  O T A L  =  A  0.665 * ( I I V ) K [ N E ] ^  (125)  O  The f i r s t - o r d e r r a t e constants were c a l c u l a t e d from the r a t e p l o t s (Figure 29) f o r benzy]Jnitrate (A) and meso-, and dl-hydrobenzom (B and C r e s p e c t i v e l y ) .  For c i s - and trans-1,2-acenaphthenediol were c a l -  c u l a t e d by e x t r a p o l a t i o n t o zero time. Table XXII.  dinitrates A  These data are summarized i n  Table XXII Apparent F i r s t - o r d e r Rate Constants f o r the P h o t o l y s i s of Aromatic N i t r a t e E s t e r s a t 24.20°C.  In Ethanol S o l u t i o n  In Benzene S o l u t i o n Compound  ti(hrs)  kxlO^(sec  2  1.0  9.53  0.20210.023  1.4  me s o -Hydr o b e nz o i n dinitrate  6.88  0.28010.059  1.9  D  trans-1,2— Acenaphthenediol dinitrate  0.54  3.6  E  cis-1,2Acenaphthenediol dinitrate  0.46  4.2 -ot2  Benzyl n i t r a t e  B  dl-Hydrobenzom dinitrate  C  4 1 kxlO ( s e c " )  k/  13.0  -6,21  Q;31O?O-.053,  l'.O  ,2.1  3.11  0.619-0.061  2.0  2.2  io.4  d  24  d  28  I n i t i a l c o n c e n t r a t i o n 0.02 mole n i t r o x y group per l i t e r . For benzyl n i t r a t e . ° d  b  ^ o A b H  5l 0,14810.032  A  t^hrs)  In 0.02 M ether s o l u t i o n , t E x t r a p o l a t e d t o zero time.  ±  2  = 0.79 hours,  k = 2.42^0.37 x l O ^ s e c " " , 1  - 120  Instead  -  of the expected slower decomposition of the acenaphthene  n i t r a t e s because of competitive they photolysed 15-30  l i g h t absorption,  the r e s u l t s showed t h a t  times f a s t e r than those containing phenyl groups  i n d i c a t e d that p h o t o s e n s i t i z a t i o n took part i n these r e a c t i o n s D and E ) .  A p o s s i b l e explanation was  and  (Figure  29,  t h a t the naphthalene p o r t i o n of the  molecule absorbed most of the i n c i d e n t l i g h t , but the e x c i t e d aromatic moeity d i d not deactivate cence, e t c )  by the usual processes (fluorescence,  phosphores-  but r a t h e r r e l e a s e d i t s e x c i t a t i o n energy v i a energy t r a n s f e r  to the unexcited  n i t r o x y groups.  In other words the naphthalene p o r t i o n of  the acenaphthene molecule acted as a " b u i l t i n " p h o t o s e n s i t i z e r . A somewhat s i m i l a r energy t r a n s f e r but i n the been reported  opposite  f o r a mixture of benzophenone and naphthalene. n-^SC  t r a n s i t i o n and  sense  has  Benzophenone  was  s e l e c t i v e l y e x c i t e d through the  a f t e r the molecules  had  passed from the f i r s t e x c i t e d s i n g l e t state t o the f i r s t e x c i t e d  s t a t e , energy was  t r a n s f e r r e d to the unexcited  the t r i p l e t state  ( t r i p l e t — " t r i p l e t energy t r a n s f e r ) (Figure 30).  triplet  naphthalene and brought i t to The  mechanism of t h i s process has been confirmed by phosphorescence spectroscopy (179), f l a s h p h o t o l y s i s spectroscopy ( l 8 2 )  (180)  r e a c t i o n k i n e t i c measurements (181)  and  ESR  0  In the present case energy ^ s  t r a n s f e r r e d i n t r a m o l e c u l a r l y from  the naphthalene p o r t i o n to the n i t r o x y group.  E n e r g e t i c a l l y (Figure  30)  t h i s process seemed to b e ^ s m g l e t — * s i n g l e t t r a n s i t i o n s i m i l a r t o those served i n other intermolecular molecular (184)  (183)  (naphthalene —*- a l k y l i o d i d e ) and  ( n a p h t h a l e n e — a n t h r a c e n e X L I I I , XLIV and XLV)  The r a t e s of p h o t o l y s i s of benzyl n i t r a t e (k^) and hydrobenzoin (k^) d i n i t r a t e were a l s o determined i n ethanol (Figure 31 and Table X X I I ) . both benzene and ethanol  The  f a c t t h a t the r a t i o k^A-^  ob-  intra-  processes.  of mesosolutions  was  about 2 i n  s o l u t i o n s i n d i c a t e d that the same type o f - r e a c t i o n  - 121 -  30,000  F i l t e r cut  off  S T 20,000  10,000  Benzophenone  Naphthalene  N i t r a t e E s t e r Acenaphthene  <7r — fTr*  TT— ir* 1  FIGURE and within  30  Triplet-Triplet  Naphthalene  (180)  XLIII  Energy  and  1,2 A c e n a p h t h e n e d i o l  <r  Transfer B e t w e e n  Si n g l e t - S i n g l c t  Energy  Benzophenone Transfer  Dinitrates  XLIV  XLV  - 122  occurred with the two  -  n i t r a t e e s t e r s even i n d i f f e r e n t s o l v e n t s .  On the  other  hand the observation t h a t the r a t e s of decomposition of the same n i t r a t e e s t e r , meso-hydrobenzom d i n i t r a t e , was ^Et  0  :  ^EtOn"  S  k  PhH  =  8  ,  6  S  2  *  d i f f e r e n t i n three d i f f e r e n t  2 :  (  1  F l  g  u r e s  2  9  a  n  d  3  1  a  n  d  T  a  t  ,  solvents! l  e  XXH)  i n d i c a t e d t h a t the solvent i n which the photodecomposition took place pated i n the r e a c t i o n . gained  T h i s agreed with the evidence of solvent p a r t i c i p a t i o n  from the p r e l i m i n a r y experiments and product Weller  (185)  partici-  analyses.  summarized the c h a r a c t e r i s t i c s of f a s t r e a c t i o n s of  e x c i t e d molecules i n t o f o u r c l a s s e s : (a)  Quenching of fluorescence  A* + B — (b)  Or (c)  Complex  (?)  '  B  ( i )  ]  —«-A  + B  (126)  formation  A* + A — ~ A * A  (127)  A* + B —  (128)  A*B  Acid—base r e a c t i o n A*H  + B — « • A* + HB  A* + HB  (d)  (A  (probably e l e c t r o n t r a n s f e r )  — - A * &  (129)  +  B"  (130)  Isomerization A*—A*  (131)  Furthermore, i t was  shown t h a t the probable occurrence of any  these r e a c t i o n s i n the e x c i t e d s t a t e could be estimated UV  s p e c t r a i f the r e a c t i o n occurred,  state.  A recent r e p o r t  (186)  of  on the b a s i s of the  even to a minor extent, i n the ground  showed that the a c i d i t i e s of weak acids were  enhanced i n t h e i r e x c i t e d s t a t e s with respect to t h e i r ground s t a t e s .  For  example, phenol became some 20,000 times more a c i d i c upon U V - i r r a d i a t i o n (i.e.  pK =10.02, Si  pK  = 5.7) £L  according to r e a c t i o n s 129  and  132. ' '  -123 -  20.0  15 0  L  A  100-  A  \  TV  B  5 0 "  O — ix—i Q. ZD  o o  \ \  1,0-  0.5-  1  ,  2  ,  ,  ,  4  ,  1  1  6  1  8  .  1  1 0  1  12  I r r a d i a t i o n Time in H o u r s FIGURE Dinitrate  31 (A)  Hydrobenzom  Rates and  of  Photorcactions  Benzyl  Dinitrate  in  Nitrate (B)  (C)  Ether  at  of in  meso - Hydrobenzom  Ethanol  2 4 2°C  and  cf  meso -  1— 1 4  - 124 -  PhOH  +  H 0 -vFhO  +  -  2  H 0  (132)  +  3  I f one considered compounds A and B r e a c t i n g with each other i n the ground s t a t e according t o equation 133 and K°  A /  (+B) „  ** A  * \  /  1  (+B«) \  (133)  0  e x c i t e d A ( i . e . A ) a l s o r e a c t i n g with B (134);  *  K  and K  would represent  the corresponding e q u i l i b r i u m constants. #  A* According t o Weller  (+B) „  K  " A*' (+B«)  (134)  (185) equation 135 would give the r a t i o of  the two e q u i l i b r i u m constants. In  K* K  where "A~?is the frequency bands of A and A . 1  =  AE -  AE' RT  =  -  he ^ kT  (135)  A  i n t e r v a l between the long wavelength a b s o r p t i o n  Equation |^"l35 J holds with the assumption of equal r e a c -  t i o n entropies i n the f l u o r e s c e n t and ground s t a t e s "  (i.e. AH—  ^H  =  - AE'). In the present case Weller's r e a c t i o n (b) (128) could be cons i d e r e d as the formation of a charge-transfer complex and a p p l i e d t o the p r e v i o u s l y discussed (Figure 15 ) charge-transfer i n t e r a c t i o n between n i t r a t e ester and solvent according t o equation 136, and the energy l e v e l diagram i n .Figure 32.  The K /K  r a t IOS were c a l c u l a t e d from n — * T c  band (2700 A*) and  the charge t r a n s f e r bands (2900-300QA) f o r benzyl n i t r a t e XIX  )  (Figure 16 Table  according t o equation 135 and provided a sequence of values K° NE -»- Solvent===5: NE  +  Solvent (136)  NE  + Solvent,,  - NE~  'Solvent  (Table XXIII) which was c o n s i s t e n t with the order of the i o n i z a t i o n t i a l s of the s o l v e n t s .  poten-  The order of the i n d i v i d u a l c a l c u l a t e d values  - 125 -  (137)  d i d not agree w i t h the order  of experimental r a t e constants  (139),  * /o however, the r a t i o K /K  | AH  NE*  NE  Solvent*  4 C - T  bo-nd  boond  AE NE AH  NE  Figure  Solverit  32.  Energy Level Diagram f o r N i t r a t e E s t e r -Solvent Complex Excitation.  (Table XXIII) d e f i n i t e l y showed t h a t charge-transfer  i n t e r a c t i o n between  e x c i t e d n i t r a t e e s t e r and solvent was much more pronounced than the same i n t e r a c t i o n i n the ground s t a t e .  Table XXIII C a l c u l a t e d R a t i o s of Charge-Transfer E q u i l i b r i u m Constants f o r Benzyl N i t r a t e i n S o l u t i o n  Solvent  4  benzene  9.245  ether  9.53  ethanol  a  (cm)  (eV)  37,037  10.50  From reference  (142)  b £ | = 4.8350 x 10 kT  a t 24.2°C  (cm  )  (cm  )  he ^ kT A  he AN> K / O 2.303kT  33,223  3,814  18,44  8.007  8 1.0x10'  33,898  3,139  15.18  6.590  3.9xl0  6  34,247  2,790  13.50  5.857  7.2xl0  5  - 126 -  The known r e l a t i v e hydrogen-donating  a c t i v i t y of the solvents  (138) was a l s o i n c o n s i s t e n t with the order of the experimental r a t e constants  (139). Electron transfer Hydrogen t r a n s f e r  (K*) (kg)  Experimental  PhR>  t 0>  EtOH  (137)  FhH <  Et^O < EtOH  (138)  PhH<  E t 0 > EtOH  (139)  2  2  T h i s apparent anomaly disappeared i f one accepted the suggestion of Porter (187) t h a t i n s o l u t i o n both e l e c t r o n t r a n s f e r and hydrogen t r a n s f e r may occur together*  The experimental r a t e constants would then m c o r -  porate both the charge t r a n s f e r  (K ) and the hydrogen t r a n s f e r  (it,) process  constants according t o equation 140 where S-H represents the p h o t o l y s i s solvent NE+Vp?—»-NE  (singlet) '+S-H ^  K  - NE*~  &-H — ^ 2 * NE-H +  ^(triplet)  The selective n-^Tf n i t r a t e , and meso-  S  (140)  Products e x c i t a t i o n of n i t r a t e e s t e r groups i n benzyl  and dl-hydrobenzom d i n i t r a t e s (Q{ -phenyl  substituted  n i t r a t e s ) permitted an e s t i m a t i o n of the quantum y i e l d of the photoreaction. The c a l c u l a t i o n of the r e q u i r e d I ^ ^ ^ v a l u e s was c a r r i e d out according t o 0  equation 125 as i l l u s t r a t e d i n Figure 33. The values of j ^ ^ ^ " f o r meso0  8  and dl-hydrobenzoin d i n i t r a t e s were e s s e n t i a l l y the same and f o r benzyl n i t r a t e h a l f of t h i s f i g u r e was used since the change from d i - t o monos u b s t i t u t i o n reduced C by one h a l f .  Quantum y i e l d s ( 0 ) were then c a l c u -  = CxXj I  l a t e d from equation 141 where k  . 0 = Rate of decomposition Rate of e x c i t a t i o n  S  5i _ ~  k  .  0 e  xp 0 ^ 0 I  total A  ^expj^ =  k INE1 1 I J  (141)  3 O  o c  IQ ( m i c r o e i n s t e i n / s e c )  O ro  O bo  p  O  3 <<a.X m O  ro 3  O  ^ CD  o  3  _l_  o  (Molar  o  Extinction  o  ro O  Coefficient)  o  o ZD  o  "  2  t" «  _l_  O  OJ  CD  _l £  OJ  ro  ro  m 3  CP m  ~  3  Q- R  a to  ° < *<a  R ro  c  3 O 3 ^ N R  n  Q  3  a.  R l/i  3" Ocr o  R D.  a  ro  - 128 _  The numerical values f o r  i n both benzene and non-absorbing  solvents  ( a l c o h o l and ether) are t a b u l a t e d i n Table XXIV.  Table XXIV C a l c u l a t e d Values of k^ f o r cx -Phenyl S u b s t i t u t e d N i t r a t e E s t e r s i n Benzene and i n Ethanol and Ether S o l u t i o n s *  A  9 1  (A) (mole  I xlO  6  1 cm ) ( e m s t e j n .sec ) 0  I x£xl0 ° (sec cm  3341  0.4  0.301  0.120  3130  2.8  2.033  5.692  3025  7.0  0.670  4.690  2967  12.0  0.441  5.292  2894  23.0  0.110  2.530  2804  42.0  0.072  3.024  2753  49.0  0.020  0.980  2700  50.0  0.014  0.520  2652  48.0  0.030  1.440  2571  35.0  0.002  0.070  10 xLxAl xt= 6  o  10  6  )  1^ x 10 (se<5 ) 6  -1  6  x2 I x £. 0  in benzene  i n alcohol and ether  21.35  24.36  14.20  16.20  * See equation 125 and F i g u r e s 28 and 33.  The c a l c u l a t e d quantum y i e l d s are l i s t e d i n Table XXV.  They were  reasonably c o n s i s t e n t f o r the three n i t r a t e e s t e r s i n one solvent and thus there was l i t t l e doubt t h a t they a l l reacted by the same mechanism.  Further-  more i n benzene s o l u t i o n 0 was approximately 2 i n d i c a t i n g t h a t two moles of  -  129  -  of n i t r a t e esters were decomposed per mole quanta ( e i n s t e i n ) and t h i s was agreement with the proposed mechanism (Figure 27) s u l t s of product analyses*  been shown ( l 2 l )  I t has  y i e l d f o r the gas phase p h o t o l y s i s of NOg of NO^  which was  photodecomposition proceeded by N-O  based on the r e -  that the maximum quantum  a l s o 2 and  was  m  since the mechanism  bond cleavage (69) t h i s l e n t some  support to the idea t h a t the f i f t h mode of s c i s s i o n (Figure 4) was  predomi-  nant i n the s o l u t i o n p h o t o l y s i s of n i t r a t e esters r a t h e r than the homolytic f o u r t h mode (Figure 4) as i n the case i n thermolysis  Table  and gas phase p h o t o l y s i s .  XXV  C a l c u l a t e d Quantum Y i e l d s f o r the P h o t o l y s i s of <=*. -Phenyl S u b s t i t u t e d N i t r a t e E s t e r s i n Three D i f f e r e n t Solvents  Solvent  k-xlO  k  4  (sec  )  exp  0  xlO^(sec - ) 1  A  B  C  A  B  C  0.202  0.280  2.08  1.42  1.97  0.619  3.83  -  3.82  Benzene  0.1420  0 148  Ethanol  0.1620  0,310  Diethylether  0.1620  o  _  As  benzyl n i t r a t e  B:  dl-hydrobenzoin d i n i t r a t e  C:  me s o-hydr obenz o i n d i n i t r a t e  The  at 24.2°.  _  2.42  f a c t that the quantum y i e l d s obtained  _  i n ethanol and  14.9  ether  were considerably higher than those i n benzene pointed to a chain mechanism i n the former s o l v e n t s , however, f u r t h e r work would be r e q u i r e d to decide whether they were r e a l l y f r e e r a d i c a l chain processes or whether the mechanism simply r e q u i r e d a l a r g e r i n t e g r a l number of molecules of n i t r a t e ester per quantum than i n the case of benzene s o l u t i o n s .  - 130  D.  ESR  -  Study of N i t r a t e E s t e r P h o t o l y s i s .  The p h o t o l y s i s of the n i t r a t e e s t e r s was of an e l e c t r o n s p i n resonance (ESR)  c a r r i e d out i n the c a v i t y  spectrometer i n the hope t h a t f r e e r a d i c a l  intermediates might b u i l d up a s u f f i c i e n t l y high steady s t a t e concentration to give a detectable s i g n a l s  This was  found to occur and s i g n a l s obtained from  the v i c i n a l d i n i t r a t e s i r r a d i a t e d i n benzene s o l u t i o n at room temperature are shown i n Figure The  34.  spectra of the f o u r n i t r a t e e s t e r s were very s i m i l a r , however,  the d i s t i n c t l y greater i n t e n s i t y of the spectrum of the 1,2-acenaphthenediol d i n i t r a t e s compared to the hydrobenzoin d i n i t r a t e s i n d i c a t e d a higher steady s t a t e concentration of r a d i c a l intermediates  i n agreement with the k i n e t i c  and the p r e v i o u s l y proposed energy t r a n s f e r process. (G.E.-A-H6) was  A more powerful  used f o r the i r r a d i a t i o n of the dl-hydrobenzoin  (Figure 34, D), however, the i n t e n s i t y of ESR  spectrum was  data lamp  dinitrate  only s l i g h t l y i n -  creased over t h a t of the meso-isomer (Figure 34, C) at the same microwave power (100 m  W).  The  s t a b i l i t y of these f r e e r a d i c a l species was  demonstrated i n an  experiment (Figure 35) where the i r r a d i a t e d trans-1,2-acenaphthenediol n i t r a t e was  kept i n the dark at room temperature.  The  di-  spectrum obtained  a f t e r ten days with the same microwave power (10 m Watts) (Figure 35)  was  extremely weak compared to the o r i g i n a l s i g n a l , however, a more intense microwave power (330 mW)  revealed t h a t the species r e s p o n s i b l e f o r the spec-  trum had not decayed completely.  This e x t r a o r d i n a r y long l i f e t i m e suggested  that the f r e e r a d i c a l present was  probably some s o r t of r e l a t i v e l y s t a b l e  complex with an odd e l e c t r o n . Recently C a l v i n and coworkers (l88) reported ESR  spectra o r i g i n a t i n g  from i n t e r a c t i o n of c h l o r a n i l (tetrachlorobenzoqumone) and N,N,N ,N* , - t e t r a f  J  3450 1  i  _1 196  FIGURE and and Room  .  34  ,  ,  3400 1 .  1 198  Steady  trans-( B) _d_l-(D)  .  State  .  .  1 200  ESR  Temperature  .  ,  Spectra  1,2-Acenaphthcnediol  Hydrobenzom  .  Dinitrates  3350 1 , 1 202  of  .  . 1 2 04  Benzene  and  3300 1—  1  Irradiated  Dinitrates in  ,  ,_ g  c i s - (A)  meso-(C)  Solution  H  at  - 132 -  H( gauss) H  3450  1  3400  1-  I —I  H  196  19 8  .  ,  ,  ,  3350 L_A  200  3300 1  1  202  1_  204  g-  A ( 1 0 mW)  B (10 mW)  C ( 330mW)  FIGURE diol the  35  Dinitrate Dark  ( B  ESR  Signals  Obtained and  C )  of  Initially  Irradiated  trans-1  (A)  After  and  2-Acenaphthene  Ten  Days  in  - 133 -  methyl-p-phenylenediamine which involved charge-transfer complex and semiquinone r a d i c a l .  The r e a c t i o n occurred i n s e v e r a l stages but "the f r e e  r a d i c a l s disappeared  completely  i n the course of one week" (188).  No ESR s i g n a l was detected i n i r r a d i a t e d a l c o h o l s o l u t i o n s of the nitrates.  This r e s u l t could be r a t i o n a l i z e d i n a t l e a s t three d i f f e r e n t  ways: (1)  The spectrum obtained i n benzene s o l u t i o n was not due t o the  transforming n i t r a t e e s t e r but r a t h e r t o the n i t r o p h e n o l formation and thus i t d i d not occur i n ethanol s o l u t i o n .  The experimental  observation t h a t  s i g n a l s appeared instantaneously i n the benzene s o l u t i o n would not favour t h i s explanation. (11)  The s p e c t r a obtained were due t o the transforming n i t r a t e  ester but the mechanisms were d i f f e r e n t i n the two s o l v e n t s .  Although the  photo-products which o r i g i n a t e d from the v i c i n a l d i n i t r a t e s were the same from benzene and a l c o h o l s o l u t i o n s i t was s t i l l p o s s i b l e , but not very that there was a d i f f e r e n c e i n the f r e e r a d i c a l (ni)  likely,  intermediates.  The s p e c t r a were due t o the transforming n i t r a t e e s t e r but  the concentration of the species with unpaired spins was too low f o r detection.  T h i s t h i r d p o s s i b i l i t y agreed with the p r e v i o u s l y proposed  t r a n s f e r complex formation  (e.g. from k i n e t i c s ) since K  charge-  f o r a l c o h o l was  small, t h e r e f o r e , the complex concentration was low and a continuous removal of the complex from the system (large kg) would decrease state concentration f u r t h e r .  fast  the steady  The s i t u a t i o n was d i r e c t l y opposite t o t h i s  i n benzene s o l u t i o n s and the proposed mechanism would t h e r e f o r e a l s o exp l a i n the d i f f e r e n c e i n ESR behaviour. The  s p l i t t i n g i n the spectrum of NO^ was about 50 gauss while the  s p l i t t i n g of the three main l i n e s i n these s p e c t r a (Figure 34 and 35) was  - 134 -  FIGURE  36  ESR  Spectrum  and  (B)  Generated  in  EPA  at  77°  K.  from  of  N0  2  (A)  in  Solid  Argon  trans-1 2 - A c e n a p h t h c n c d i o l (  (214)  Dinitrate  - 135 -  about 30 gauss and therefore the s o l u t i o n s d i d not contain amounts of NO2.  appreciable  I f the mechanism of the photodecomposition r e a l l y  RO-NO2 s c i s s i o n as found i n gas phase photolyses  involved  and the l i b e r a t e d NC^ was  responsible f o r the r e a c t i o n with the solvent then, at the steady s t a t e concentration, NX^ should have been d e t e c t a b l e .  Since the spectrum of  NO2 d i d not appear a t room temperature the ESR r e s u l t s e s t a b l i s h e d the p r e v i o u s l y suggested f i f t h mode of s c i s s i o n (Figure 4) as the primary cleavage i n s o l u t i o n p h o t o l y s i s of n i t r a t e e s t e r s . I r r a d i a t i o n of n i t r a t e e s t e r i n EPA  (ether-i-pentane-alcohdl  8s3:5 v o l / v o l ) glass a t 77°K, however, d i d give r i s e t o NO2 as shown i n Figure 36. This phenomenon could be r a t i o n a l i z e d as f o l l o w s :  The time  r e q u i r e d f o r " r e a c t i v e i n t e r a c t i o n " with surrounding solvent molecules a t 77°K might be longer than the l i f e t i m e of the e x c i t e d s t a t e .  Thus the ex-  c i t e d s t a t e , not making contact with r e a c t i v e molecules w i t h i n i t s  1  life-  time, as i n gas phase, underwent decomposition a t the weakest point, i . e  0  the R0-N0 bond. 2  In a c o n t r o l experiment NO gas was i r r a d i a t e d i n benzene s o l u t i o n at the same i n i t i a l n i t r o g e n concentration esters.  (0.2 M) as used f o r the n i t r a t e  The close s i m i l a r i t y of the spectrum obtained  t o t h a t obtained  with  the aromatic n i t r a t e e s t e r s (Figure 37) pointed t o a s i m i l a r intermediate i n the two cases.  The products from these r e a c t i o n s were a l s o s i m i l a r as men-  tioned i n a previous  section.  In a l l ESR spectra obtained  from p h o t o l y s i s of n i t r a t e e s t e r s  l i n e s were d i s t i n g u i s h e d as major components.  three  These were a t t r i b u t e d t o the  s p l i t t i n g of the e l e c t r o n resonance by a n i t r o g e n atom ( f o r ^ N , 1=1) which meant that the unpaired X=Irradiation  s p i n was located on a n i t r o g e n atom. of s i n g l e c r y s t a l s of potassium n i t r a t e (mounted  - 136 -  —  .  3450 1  1  _1  H  1  1.  .  196  (gauss)  3400 1_—I 1  1  1  1  3350 1  I  1  I  198  200  202  1  1  1  •  1  3300 1—  \ 204 g  A (10 mW)  ( 1 0 0 mW)  FIGURE diol  37  Dinitrate  Solution .  ESR (01  Spectra M)(A)  of and  Irradiated NO  t r a n s - 1 , 2 - Ace n a p h t h c n c -  (02M)(B)  in  Benzene  -  137-  p a r a l l e l or perpendicular to the major c r y s t a l a x i s ) was reported to generate n i t r a t e i o n negative i o n , (NO")  which had. s p l i t t i n g s of 62 gauss and 32  p<tr* gauss measured i n the p a r a l l e l and^pendicular o r i e n t a t i o n s r e s p e c t i v e l y (  189 )»  The measured s p l i t t i n g between the three mam  l i n e s of the spectra  of n i t r a t e e s t e r s i r r a d i a t e d i n benzene s o l u t i o n (33.2 +1.6 close to one of these v a l u e s .  gauss) was  quite  The question was t h e r e f o r e r a i s e d as t o  whether a n i t r a t e e s t e r negative i o n generated from a charge-transfer i n t e r a c t i o n between e x c i t e d n i t r a t e e s t e r and benzene solvent might not be r e sponsible f o r the spectrum.  I t was  n o t i c e d from the f i n e s t r u c t u r e of the  spectra t h a t the middle l i n e was more intense than the two outside l i n e s , i n d i c a t i n g that the spectrum was one f r e e r a d i c a l .  r e a l l y a r e s u l t a n t spectrum of more than  Since a l k o x y l r a d i c a l s , uncoupled by neighbouring protons,  u s u a l l y e x h i b i t s i n g l e peaks, a p o r t i o n of the c e n t r a l l i n e was assigned to an intermediate aromatic a l k o x y l r a d i c a l . f i n e s t r u c t u r e was  tentatively  Furthermore,  additional  observed as shoulders on the c e n t r a l l i n e which were c l e a r l y  d i s t i n g u i s h a b l e at the e a r l y stage of i r r a d i a t i o n and p r a c t i c a l l y disappeared later. In order to check the a c t u a l p o s i t i o n of these l i n e s a k i n e t i c periment was  ex-  c a r r i e d out i n which spectra were taken at f i x e d time i n t e r v a l s  r a t h e r than at steady state c o n c e n t r a t i o n . F i g u r e 38 shows a t y p i c a l  spec-  trum of these s e r i e s taken from photolysed trans-1,2-acenaphthenediol d i n i t r a t e a f t e r one hour.  At t h i s e a r l y stage of i r r a d i a t i o n the s a t e l l i t e peaks  c l o s e to the centre l i n e became c l e a r l y observable and they were a t t r i b u t e d to the outside p a i r of a second s e t of three l i n e s , the middle one being hidden at the c e n t r e .  The spectrum showed some asymmetry i n d i c a t i n g that  the centres of the two  ^ ^ u - f a g g  sets of three l i n e s were not e x a c t l y co-  i n c i d e n t which i n t u r n proved that the o r i g i n s of two sets were two ferent free r a d i c a l species.  dif-  The measured g values f o r the centres of the  - 138 3450 — i  3400 1  ,  196  3350  1  1  198  1  3300  1  2 00  1  1  2 02  H  (g  a u s S  )  g  2 04  C FIGURE  38  ESR  Spectrum  and  Components  trans-1,2-Acenaphthcncdicl  TABLE  XXVI  Observed  Components  of  Nitrate  Esters  Irradiated  Component  Multiplicity  g  value  A  triplet  2 00121  B  triplet  2 00302  C  singlet  2.00162  Splitting Mc/s ' 82.44 36.33'  of  Irradiated  Dinitrate  ESR  (A)  Spectra  of  L i n e Width  gauss  gauss  29.41  7.95  12.96  5.16  —  8 36  (AH)  -  two sets of t r i p l e t s  139*-  as w e l l as the coupling constants ( A H  in, gauss) are  l i s t e d i n Table XXVI. A r a t e p l o t (Figure 39) showed the generation of these components with time of i r r a d i a t i o n and i n d i c a t e d t h a t the course of the r e a c t i o n shown i n equation  was  142,  "  A  B  -C  (142)  Species C could not be the phenoxyl r a d i c a l of the forming n i t r o — phenol since the phenoxyl r a d i c a l showed a more complex spectrum  (190).  If.  however, C represented some other intermediate a l k o x y l r a d i c a l , then B and A represented some form of the transforming n i t r a t e e s t e r . e s t e r r a d i c a l , RONOgH, which was  Protonated n i t r a t e  p r e v i o u s l y suggested as the f i n a l  mediate (140) before the n i t r o x y group decomposed, might have to B.  However, the s i m i l a r i t y between the spectrum  inter-  corresponded  of photolyzed benzene—NO  mixture and photolyzed n i t r a t e e s t e r i n benzene s o l u t i o n would be b e t t e r explained i f the spectrum of component B was where the unpaired s p i n was  assigned t o a negative i o n  l o c a t e d mostly on n i t r o g e n .  This assignment  might be s e t t l e d i f n i t r a t e e s t e r negative i o n were generated by some a l t e r n a t i v e means, e.g. by e l e c t r o l y t i c r e d u c t i o n , i n the ESR  spectrometer.  I f the chemical assignments of C and B were accepted as d i s c u s s e d above then only the nature of A remained i n q u e s t i o n . ceded B and C (Figure 39) i t was due t o the n i t r a t e e s t e r nVFC  Since A must have p r e -  tempting t o suggest t h a t A might have been  t r i p l e t state m  steady state c o n c e n t r a t i o n .  Weisman^ (19$) pointed out t h a t "with randomly o r i e n t e d molecules i n r i g i d or f l u i d solvents ........ the d i r e c t magnetic d i p o l a r couplings between the unpaired e l e c t r o n s i n the t r i p l e t s t a t e " was f a i l u r e to observe ESR  spectra.  the reason f o r  He a r r i v e d a t the c o n c l u s i o n t h a t t r i p l e t  states might be detectable i f the "molecules c o n t a i n i n g two unpaired ^ c  — 140 -  0  -1  1  2  IRRADIATION  FIGURE ESR  39  Spectrum  Rates of  of  3 TIME  IN  Generation  Irradiated  4  HOURS  of  Nitrate  Components Ester  of  - X41 -  e l e c t r o n s are......  *far apart  h i g h l y symmetrical"  (l9l).  There were two  1  or i f t h e i r d i s t r i b u t i o n about each other i s  s p e c u l a t i v e reasons why  n-»ic  n i t r a t e e s t e r s might have been more e a s i l y detectable states.  The  t r i p l e t s t a t e s of than f t —>fZ  triplet  l a t t e r have already been reported by Hutchison and Mangum  (192)  f o r o r i e n t e d naphthalene molecules i n durene and by Parmer, Gardner, and McDowell (182)  f o r randomly o r i e n t e d naphthalene molecules i n EPA  glass  at 77°K. (I)  In a'vC-^TT  t r i p l e t state cnecof Ihe e l e c t r o n s would be  i n the lowest antibonding TC and  it  n—*"fiT  would be perpendicular t r i p l e t s t a t e one  (n) which was  m  a l s o to n  (TC), both of the o r b i t a l s , i . e . ItT  to the plane of the molecule.  In an  e l e c t r o n would be l o c a t e d i n the nonbondmg o r b i t a l  the plane of the molecule while the other  molecular antibonding and  orbital  f t - o r b i t a l perpendicular  one would be m  (178).  state i n c l u d i n g that of carbonyl  the two  excited  as w e l l as n i t r a t e e s t e r .  While i n the n-^Tu  e x c i t e d state of a carbonyl  compound  unpaired spins would be l o c a t e d w i t h i n the neighbourhood of  carbon and  one  a  to the plane of the molecule  These c r i t e r i a would be v a l i d , i n general, f o r any n-^HT  (II)  located  one  oxygen atom, i n a n i t r o x y group they would be expected to  spread over the three atom u n i t (NC^)  i n such a way  t h a t while one  electron  would be i n the antibonding TC - o r b i t a l and might be l o c a t e d mostly on n i t r o g e n , the other e l e c t r o n would be d i v i d e d between the nonbflndmg p - o r b i t a l s of the two  oxygen atoms (193)  and t h i s s t e r i c s i t u a t i o n would decrease t h e i r d i r e c t  interaction. Although the ESR  i n v e s t i g a t i o n p o s i t i v e l y proved the f r e e r a d i c a l  mechanism of the n i t r a t e e s t e r p h o t o l y s i s , more work would be r e q u i r e d t o  - 142, -  f i n a l i z e the proposed assignments. ESR evidence was  obtained f o r the intramolecular  energy t r a n s f e r  process between the naphthalene moiety and n i t r o x y group i n the nitrates.  The |L->TC  acenaphthene  t r i p l e t s t a t e of the hydrocarbon acenaphthene was  ob-  served at 77°K i n EPA g l a s s at g - 4 (Figure 40) and appeared much the same as the ESR t r i p l e t state spectrum of naphthalene (182) ( 1 9 4 ) ^ 0 ESR of the t r i p l e t naphthalene was  signal  obtained, however, from the i r r a d i a t e d t r a n s -  1,2-acenaphthenediol d i n i t r a t e . The absence of the t r i p l e t state s i g n a l i n d i c a t e d t h a t although the naphthalene p o r t i o n became e x c i t e d according t o i t s UV-spectrum, the system d i d not reach i t s phosphorescent t r i p l e t  state  because of the energy t r a n s f e r from the s i n g l e t e x c i t e d state to the unexcited n i t r o x y group. i n Figure  With t h i s r e s u l t the energy t r a n s f e r process as i l l u s t r a t e d  30 was considered to be  E  0  established.  Summary of Proposed Reaction Mechanism.  The proposed mechanism i s summarized i n Figure  41.  I r r a d i a t i o n of a n i t r a t e e s t e r i n the range of the n—*-To  band  brings the n i t r o x y group to the f i r s t e x c i t e d s i n g l e t state from which i t i s t r a n s f e r r e d by a r a d i a t i o n l e s s process t o the lowest e x c i t e d t r i p l e t  state.  Both of these states may lose t h e i r e x c i t a t i o n a l energy by p h y s i c a l d e a c t i v a t i o n processes or they may undergo chemical r e a c t i o n .  The chemical r e a c t i o n  that occurs may be a s c i s s i o n of the weakest bond (RO-NOg) i f no . / p o s s i b i l i t i e s are a v a i l a b l e f o r combination with other molecules as m frozen glass.  the gasLphase ' o r n n a  I f , however, the e x c i t e d n i t r a t e e s t e r comes i n t o contact with  other molecules before breaking up t o fragments then other types of r e a c t i o n may  occur as i n s o l u t i o n p h o t o l y s i s .  suggested sequence  Equation 140  (Figure 41) describes ./the  of steps o c c u r r i n g during decomposition m  solution.  — 143  _H  H (gauss)  1400  -  1  1  1  1  1450  1500  1550  1600  FIGURE  40  ESR Triplet  Spectrum State  of in  r— 1650  Acenaphthcne EPA .  - 144 -  #  RONO, (Singlet)  RONCL k  S-H R0N0 .•• 2  +  RONOgH + S  .. SH  K  RONO, ( t r i p l e t )j  R0° I  +  NO  «  ^2.  *  H0_» _ + _S ^ I  :  •  S k e l e t a l Products  Figure 41.  RONO +  Products from Solvent  Proposed Mechanism of N i t r a t e E s t e r P h o t o l y s i s In S o l u t i o n .  The  products obtained from the e s t e r RONO^, are f u n c t i o n s  of the  s t r u c t u r e of RO* and the products formed from the solvent depend on the nature of the system H0» + *S. The t i o n (ho^)  f i r s t step of e x c i t a t i o n may take place by d i r e c t l i g h t absorp-  or by an energy t r a n s f e r process.  The f i r s t two steps ( e l e c t r o n i c  e x c i t a t i o n s ) should be the same f o r the p h o t o l y s i s i n the gas phase, s o l u t i o n , or f r o z e n g l a s s , but the d i s t i n c t i o n comes a t the t h i r d step when the solvent (or added a c t i v e s o l u t e , l i k e diphenylamme (105)) becomes involved i n the reaction.  Evidence f o r t h i s charge-transfer  i n t e r a c t i o n (K ) may be gained  only by p h y s i c a l measurements i f the e l e c t r o n donation goes i n t e r m o l e c u l a r l y , however, when the charge—transfer  process occurs i n t r a m o l e c u l a r l y chemical  evidence may also confirm t h i s step as i t i s r e f l e c t e d i n the nature of the  - 145 -  products. I t i s very l i k e l y t h a t the s i g n i f i c a n t d i f f e r e n c e i n the photol y t i c products from benzoin n i t r a t e a n CX -keto n i t r a t e e s t e r , and from the ?  other aromatic n i t r a t e s may be explained  by an intramolecular  process (XLYl)  which would a l t e r the course of the r e a c t i o n i n the former case. (195)  A recent  discovery that i n the p h o t o l y s i s of l , 2 j 5,6-di-<V-isopropylidene  -D-glucopyrannse - 3 - n i t r a t e i n methanol s o l u t i o n the s p l i t t i n g o f f of the 5,6-isopropylidene group preceded the p h o t o l y s i s of the n i t r o x y group p r o ducing the corresponding l , 2 - 0 - i s o p r o p i l i d e n e - 3 - ^ - n i t r o glucose a l s o toward an intramolecular  XLVI  charge-transfer  process  pointed  (XLVII).  XLVII  In c o n c l u s i o n , t h i s work suggested t h a t the s o l u t i o n p h o t o l y t i c r e a c t i o n s be regarded, not as photodecompositions of the n i t r a t e e s t e r s , but r a t h e r as the r e a c t i o n s of the e x c i t e d n i t r a t e e s t e r s with p a r t i c u l a r reagents.  This obvious d i s t i n c t i o n should not be overlooked i n s y n t h e t i c  a p p l i c a t i o n s of such photochemical r e a c t i o n s .  - 146 -  EXPERIMENTAL  - 147  -  I.  Materials.  A.  Solvents.  Organic solvents of reagent grade were d i s t i l l e d through a 22  cm.  Vigreaux column before use except as f o l l o w s : Absolute E t h a n o l . e t h y l phthalate method (196). determined  Reagent grade absolute ethanol was The moisture content was  d r i e d by the  l e s s than 0.005% as  by K a r l - F i s c h e r t i t r a t i o n s . Absolute Ether ( p e r o x i d e - f r e e ) .  The reagent was  prepared imme-  d i a t e l y before use by d i s t i l l i n g anhydrous ether from l i t h i u m aluminum hydride. Absolute Benzene (oxygen-free). benzene (No, 7216,  Merck reagent grade "fiiiophene-free  s u l f u r content 0.005%) was r e p e a t e d l y d r i e d over sodium  and f r a c t i o n a l l y d i s t i l l e d .  The b o i l i n g point obtained (79.0°C/746  f i t t e d the Cox diagram ( l o g p versus 10 /Tbp) the sample was  f o r benzene.  mm.)  The p u r i t y of  chedked by vapor phase chromatography on a 1 m.  "Tergitol  (10% on C22 f i r e b r i c k ) NP 27" column at 75° under helium flow (55 ml/rain) which i n d i c a t e d the presence  of minor amounts of lower b o i l i n g  The d i s s o l v e d oxygen was  impurities.  purged with a stream of n i t r o g e n gas  (washed with a l k a l i n e p y r o g a l l o l and d r i e d with s u l f u r i c acid) u n t i l the u s u a l l y observable ESR  s i g n a l disappeared and the benzene sample was  stored  i n the dark under n i t r o g e n . Anhydrous P y r i d i n e . A commercial reagent grade sample f F i s c h e r  :  S c i e n t i f icsComp"anyvoP*368^ "*asistor&d"over calesum. h y d i i d e c f or La.weekoand l  distilledl/fromcfresB' oa^ciumchydride* o_ .  ,  - 148  B»  Reagents  2,4-Dmitrophenylhydrazine. methanol was  1.5  g of the free base m  of g l a c i a l a c e t i c a c i d . 100 mg  A s o l u t i o n of the f r e e base i n  a c i d i f i e d with s u l f u r i c a c i d  4-Nitrophenylhydrazme.  (196).  The reagent was  prepared by d i s s o l v i n g  50 ml. of absolute ethanol a c i d i f i e d with 1 ml. From 3 t o 5 ml. of the reagent was  samples of the unknown aldehyde Anhydrous N i t r i c A c i d .  Chemical, No. 1121)  -  (196).  Reagent grade fuming n i t r i c a c i d  c o n t a i n i n g a minimum of 90$ HNO^,  21.4 m o l e s / l i t e r ) was  used f o r about  (d  =  (Allied  1.49-1.50,  vacuum d i s t i l l e d a f t e r mixing with an equal volume  of concentrated s u l f u r i c a c i d i n an a l l g l a s s apparatus with b u i l t i n 6-plate d i s t i l l i n g column. was  The c o l o u r l e s s a c i d was  stored a t —20°C and  used w i t h i n 6 months (196). Ethylchlorofornate«  Chemicals) was  Reagent grade m a t e r i a l (Eastman Organic  stored over anhydrous calcium carbonate and was d i s t i l l e d  through a 20 cm. Vigreaux column j u s t before use, b.p. 93.5-97.5^/755 reported b.p. 95°/760 mm.  mm.,  (197).  Palladium-Charcoal C a t a l y s t .  T h i s was  prepared according to  Hartung (198) from palladium c h l o r i d e (Baker Platinum of Canada Ltd.) and acid-washed "Darco-G-60" c h a r c o a l (Atlas Powder Co., New  C.  Reference Compounds.  meso- and d l - Hydrobenzom D i a c e t a t e s .  The isomeric hydrobenzoms  were a c e t y l a t e d with a c e t i c anhydride and p y r i d i n e (196). (1.072 g) y i e l d e d 1.10  York).  meso-Hydrobenzoin  g of d i a c e t a t e which melted at 137.5-138.0°; reported  TABLE  XXVII  Melting  Points MP  Parent  Formul a  Compound  and  *  Reported  0 N 2  NMR  ( °C )  d  NMR  Obtained  192-193  195-197  2  H  9  Propion aldehyde  c b  H  ,C=N — R  f  Acetone  Benzaldenyde  H C-C=N—R eH 3  i h C H - C H - C = N—R 3  2  H C 3  j  C  8  7  166  b  c  I!  IM,  II  in 6  —  Tnfluoroacetic 5  s  4  —  3  2  1  0  HgC  )C = N - R  1G8  155  128  „„ll f  165.0-165 5 II  llllllll  ll  9 mi III  154-155  H  C =N — R  237  m.  II Insoluble  238-239  f o r C ^ H ^ C ^ : C , 5 4 5 5 ; H, 3 5 2 , N, 19 57 <>/<,.  ' II  J  126-127 II  6 5,  h 111!IH  2  3  in t n f l u o r o a c e t i c 4  5  6  7  Reference (196)  * * Calculated  Acid  d  167-168  1  *  2,4 -Dimtrophenylhydrazones  Spectra  a  II Acetaldehydc  of  n  N-HNONO ~ )N-R Formaldehyde  Spectra  Found-C, 54.28,  H, 3 6 9 ; N, 19 43°/.  acid 8  9  10  - 150 -  m.p. 135° (197).  dl-Hydrobenzoin monoacetate (1.025 g) y i e l d e d a t o t a l of  1.05 g of d i a c e t a t e which melted a t 108-109°; reported m.p. 109-110°C (197). The d i a c e t a t e s were chromatographically homogeneous and the NMR  (TLC; M-3, S-3, R - l )  spectra showed no unassigned proton s i g n a l s .  2,4-Dinitrophenylhydrazones  of ReferenceCarbonyl  2,4-dinitrophenylhydrazones were prepared  Compounds.  (196) from reagent grade  and ketones with the 2,4—dinitrophenylhydrazine reagent.  The  aldehydes  The products were  twice r e c r y s t a l l i z e d from a l c o h o l and d r i e d over phosphorus pentoxide and were then pure (TLC; M-4, S-2, or S-7, or S-8). The melting points and NMR  spectra of these compounds are summarized i n Table XXVII.  Nitrophenols. The melting points and NMR  s p e c t r a of the n i t r o p h e n o l s obtained  and p u r i f i e d as described below are summarized i n Table 2-Nitrophenol  XXVIII.  (XLVTIl) (BDH) was r e c r y s t a l l i z e d from benzene-  petroleum ether (30-60°) mixture. 4-Nitrophenol  (XLIX) (BDH) was used without f u r t h e r p u r i f i c a t i o n .  2 4-Dinitrophenol t  graphed on a 30x500 mm. the f o l l o w i n g order: ethyl acetate.  (L)  (Eastman Organic Chemicals) was chromato-  s i l i c a g e l column, e l u t e d with s o l v e n t mixtures i n  petroleum ether (30-60°) -benzene, benzene, and benzene-  The product thus obtained was f r e e of the 2,6-isomer.  2,6-Dinitrophenol  ( L l ) ( A l d r i c h Chemical Co.) was r e c r y s t a l l i z e d  from benzene-petroleum e t h e r . 2,4,6-Tnnitrophenol  ( p i c r i c acid) ( L l l ) (General Chemical and  Pharmaceutical Co. L t d . , England) was r e c r y s t a l l i z e d from chloroform. Nitrated-4-Phenylphenols.  To a n i t r a t i n g mixture of 3.8 ml. of  fuming n i t r i c a c i d , 6 ml, of g l a c i a l a c e t i c a c i d and 6 ml. of a c e t i c  — 1 51 — T A B L E XXVIII  Melting Points  and  NMR  Spectra  of  Nitrophenols .  rn p ( °  COMPOUND Obt  0N 2  XLVII I  H0<Q>NO  2  0N HO<^^N0  XLIX  2  2  L  Rep  C  )  Ref  44 54 -4 9  197  45 0 114 51 -14  115 5  116.5113  NMR  Spectra  in  —  9  «®  LI  C2N  HC<Q)NO 0N 2  Lll  2  i  7  i  i  0N 0N 2  0N 2  63 5-63 64 64 0 123122 5  11  1  III  197  157-154158 155  LV  11  197  LIV  2  III  197  60- 67 62  O^  6 i  mill  IIII  LIU  OgN  —  8  I  C^N  0  Acetone  z\s  208 201 209 202  Z\6 ..1  ..I,  ..  ...  ..  .  216  1  —p—  —  1  2  1  T  1  3  r  4  - 152  anhydride 4-phenylphenol  -  (3.4 g, Eastman Organic Chemicals) d i s s o l v e d i n a  mixture of a c e t i c a c i d (20 ml.) and a c e t i c anhydride (10 ml.) was slowly w i t h vigorous s t i r r i n g .  The temperature  was kept between 0° and 8° f o r two hours.  added  of the n i t r a t i n g mixture  A f t e r an a d d i t i o n a l one hour of  s t i r r i n g at room temperature, the mixture was t r a n s f e r r e d t o ice-water and the p r e c i p i t a t e d product was c o l l e c t e d .  T h i n l a y e r chromatography (M-3,  S—3)  i n d i c a t e d the presence of s e v e r a l aromatic n i t r o compounds ranging i n c o l o u r from pale y e l l o w t o dark orange-yellow and i n R^ values from 0.0-0.9.  Silica  g e l column chromatography s i m i l a r t o that used f o r 2,4-dinitrophenol p r o v i d e d three mam rechromatographed  f r a c t i o n s A,B  and C i n that order of e l u t i o n and these were  and r e c r y s t a l l i z e d from benzene.  F r a c t i o n A (65 mg) was 2-nitro-4-phenylphenol ( L l l l ) since both the low y i e l d and the h i g h R^ value on TLC pointed to monosubstitution and the m e l t i n g p o i n t (Table XXVIII) was  close t o the reported v a l u e .  F r a c t i o n B (l«85 g) gave a s i n g l e spot on TLC i d e n t i f i e d as 2,6-dmitro—4-phenylphenol and from the m e l t i n g point and NMR sets of r i n g proton s i g n a l s m  (M-3, S-3)  and  was  (LIV) from the elementary a n a l y s i s  spectrum  (Table XXVIII).  the spectrum.  One was  tuted phenyl r i n g as i n phenol, while the other was  There were two  t y p i c a l of  aomonosubsti-  a s i n g l e peak s i m i l a r t o  that of p i c r i c a c i d which would be expected from the benzene r i n g b e a r i n g the OH group and two ortho n i t r o groups. H, 3.33;  N, 11.57.  Found:  C, 55.33;  F r a c t i o n C(760 mg) was phenol  C a l c . f o r C HgO<.N l2  H, 3.41;  C, 59.51;  N, 10.62$.  suspected t o be 2 , 6 , 4 - t r m i t r o - 4 — p h e n y l -  (LV) from i t s low R^, value and t h i s was  p o i n t , a n a l y s i s and NMR  2m  confirmed from the m e l t m g  spectrum.  The arrangement of protons i n t h i s symmetric  t n n i t r o derivative  i s such that the benzene r i n g which bears the hydroxyl group would be  - 153  -  analogous to p i c r i c acxd while the other benzene r i n g n i t r a t e d on the 4 - p o s i t i o n contains f o u r protons i n an ^-^>2 y ^ s  s  would be  ems  to p - n i t r o p h e n o l . In agreement with t h i s the NMR  analogous  spectrum consisted of a t  s i n g l e peak at T = 1.21  ( f o r p i c r i c a c i d T r i 0.83)  and a quarte^f s i m i l a r  to that of 4—nitrophenol but at a lower T — v a l u e . C a l c . f o r C^B^CyKjt Found:  C, 47.39$  C, 50.18; H, 2,54}  D.  H, 2.46;  N, 14.63.  N, 13.70%.  Aromatic N i t r a t e E s t e r s ,  (i).  Starting Materials.  c i s - and trans-1,2-Acenaphthenediols.  These d i o l s were prepared and c h a r a c t e r i z e d as d e s c r i b e d by the present author i n an e a r l i e r t h e s i s (68) (144).  Benzoin. A commercial sample of benzoin (Eastman Organic Chemicals) melted c o r r e c t l y a t 135-137° (197) and t h i n l a y e r chromatography (M-3, R-3)  S-3, R - l or  i n d i c a t e d the presence of one compound only, both before and a f t e r r e -  c r y s t a l l i z a t i o n from  methanol.  me so- Hydrobenzoin.  Benzoin l i k e b e n z i l (Table XXIX) was reduced predominantly t o meso-  hydrobenzoin by both l i t h i u m aluminum hydride "in ether and by sodium  borohydride i n a l c o h o l .  - 154  Table  -  XXLX  Reduction Products of B e n z i l .  Yield Starting Material  Products  LIA1H.(199) 35  /  /  m.p*  w  Ph  "predominant"  138.5°(201)  a-. OH  0  Ph-C—C-Ph  cfe H  Benzil m.p.  96°  4  28"  -80"  OH OH Ph-C~4p-Ph H H m-Hydrobenzoin  Ph  w  3~  v  NaBH (200) rc  5$  dl-Hydrobenzom (196)  m.p.  119.5-120.5 (201)  C  Reduction of benzoin w i t h Arnd's a l l o y (Mg-Cu)(202) was  a l s o used,  but l i t h i u m aluminum hydride gave the best r e s u l t s . (a)  Benzoin (83.70 g) was reduced  (203) with l i t h i u m aluminum  hydride (95% pure, Metal Hydrides Incorporated) (16.41 g) suspended i n anhydrous ether (800 ml.) a t dry ice^»acetone temperature  over n i g h t .  The  excess  of l i t h i u m aluminum hydride was decomposed w i t h e t h y l a c e t a t e - d i e t h y l ether mix^une ( l : l ) , the complex formed i n the r e d u c t i o n was destroyed with aqueous sodium hydroxide, and the aqueous s o l u t i o n was d i e t h y l ether i n a continuous l i q u i d - l i q u i d  e x h a u s t i v e l y e x t r a c t e d with  extractor.  The residue from the ether e x t r a c t (95.8$ y i e l d ) was from methanol m B, 9.92  two f r a c t i o n s :  recrystallized  A,71.08 g, (84.1$ of the t h e o r e t i c a l ) and  g (11.7$ of the t h e o r e t i c a l ) .  Further r e c r y s t a l l i z a t i o n of f r a c t i o n  A from acetone provided pure m a t e r i a l (53.80 g, 63.7$) which melted a t  - 155 -  137.5-140.5°,  Reported m.p. 138.5° (201).  detectable by TLC (M-3| S-3| R - l or R-3).  This product gave only one spot  The u l t r a v i o l e t , i n f r a r e d and p r o -  ton magnetic resonance s p e c t r a were recorded. (b)  Benzoin (21*1998 g) was added t o an i c e - c o l d methanolic s o l u -  t i o n of sodium borohydride (7.9984 g ) .  A f t e r three hours of vigorous  stirring  the i c e bath was removed and the mixture was l e f t over n i g h t a t room temperature.  The excess borohydride was destroyed with a c e t i c a c i d and the sodium  ions were p r e c i p i t a t e d with concentrate h y d r o c h l o r i c a c i d (pH adjusted t o 6 ) . The f i l t r a t e was evaporated t o dryness and the b o r i c a c i d formed was removed by repeated d i s t i l l a t i o n s w i t h methanol. The crude product (18.842 g, 88.0% y i e l d ) was r e c r y s t a l l i z e d from 270 ml. of methanol.  Three main f r a c t i o n s were obtained:  A, 6.680 g, (31.2%) m.p. 140°C«  B, 1.691 g, (7.9%) m.p. 136-140°C: and  C, 6.118 g, (28.6%) m.p. 117-137°C.  Reported m.p. f o r me s o-Hydr obenz o i n  138.5°; f o r dl-Hydrobenzom, 119.5-120.5°C two mam  (201).  R e c r y s t a l l i z a t i o n of the  f r a c t i o n s A and C from methanol provided samples which melted a t  139.0-139.5°C and 137.0-139.5°C r e s p e c t i v e l y .  The i n f r a r e d s p e c t r a a l s o  i n d i c a t e d t h a t both were pure meso-isomer. (c)  Benzoin (1^0377 g,) was d i s s o l v e d i n methanol (75 ml.) and  the s o l u t i o n was d i l u t e d with d i s t i l l e d water (70 ml.) and 5ml. of an aqueous s o l u t i o n of magnesium c h l o r i d e (200 g, per l i t e r ) ( 2 0 4 ) . f i n e l y powdered Arnd's a l l o y (40% Mg, 60% Cu)  About 5 grams of  (205)(206) was added w i t h  vigorous s t i r r i n g , and the mixture was r e f l u x e d f o r 4 hours.  The s i l v e r  white a l l o y turned copper—red and some magnesium hydroxide p r e c i p i t a t e d out. The hot suspension was f i l t e r e d with s u c t i o n and the f i l t r a t e was concent r a t e d i n vacuo.  Three crops of c r y s t a l s were i s o l a t e d :  melted a t 138.5-140.0° j  B  ?  A, 341.3 mg (32.5%)  143.7 mg (13.7%) melted a t 136-140° and  K i n d l y s u p p l i e d by Dominion Magnesium L i m i t e d  (Domal) Haley, O n t a r i o .  - 156 -  C, 216.6 mg  (20.7$) melted over a wide range below 110°.  R - l or R-3)  i n d i c a t e d t h a t A and B were benzom-free and judging from t h e i r  melting points  TLC  (M-3,  S-3,  were pure meso-hydrobenz o i n , f r a c t i o n C, however, was  about  a 1:1 mixture of unreacted benzoin and r e d u c t i o n product.  dl-Hydrobenzom.  Racemic or dl-hydrobenzom  was prepared by a s e r i e s of three steps  according t o F i e s e r (200). In the f i r s t step meso-stilbene dibromide was prepared from grams of commercial t r a n s - s t i l b e n e (157 g ) . m.p,  100  (Eastman Organic Chemicals) i n 83$ y i e l d  The product decomposed d u r i n g m e l t i n g at 251.0-252.5°; r e p o r t e d  238°(200). In the second step meso-stilbene dibromide was  Walden i n v e r s i o n to dl-hydrobenzom  monoacetate.  transformed v i a a  T h i s r e a c t i o n was  carried  out w i t h v a r i o u s amounts (2-50 gram) of dibromide y i e l d i n g about 53$ of pure c r y s t a l l i n e dl-hydrobenzoin monoacetate which melted at 87-89°; r e p o r t e d m.p.  87° (200). In the t h i r d step the acetate group was hydrolysed and the d l -  hydrobenzom produced was r e c r y s t a l l i z e d from a d i e t h y l ether-petroleum ether (b.p. 30-60°) mixture y i e l d i n g long white needles (58$), which melted at 122.5-124.5°; reported m.p.  119.5-120.5° (200).  Benzoin Ethylcarbonate Benzoin (4.3 miLlimolej 906.0 mg) was d i s s o l v e d i n anhydrous dine (10 ml.) and 1.0 ml» formate was  pyri-  (10.5 nnllimoles, about 150$ excess) of e t h y l c h l o r o -  added to the s o l u t i o n .  The mixture was  l e f t at ..room temperature  f o r 24 hours and was heated t o 100° f o r an a d d i t i o n a l 15 minutes.  Pyridinium  TLC"did not d i s t i n g u i s h between meso- and d l - hydrobenzoms.  - 157-  1  1  1  1  j  1  j  '  —  i  i  '  i  i  i  I  '  I  I  \\  0 \  i  '  i  i  i  i  i  i  i  V  rt i  •  i  i  i  i  i  i  i  i  i  i  i  i  i  ^ D  4000  i  i / ^ ^ ^  i  i  i  V/^A  i  i  V  i  i  i  fh  3000  ,  FfGURE ethane  i  42  2000  i  1800  ,  Infrared  Derivatives  Di-( E t h y l c a r b o n a t c ) ;  ,  i  1600  Spectra  of  i  140O  Benzoin,-  D:  1  1  1200  Ethylcarbonatcs  A- m e s o - H y d r o b e n z o m ; C:  1  f  A i  Benzoin  B  1 of  I  i  A /  •  i  1  i\ f ll 1000  1  \  1/  800-cm"  1, 2-Diphenyl -  meso -Hydrobenzom Ethylcarbonate  - 158  -  c h l o r i d e separated i n c r y s t a l l i n e form d u r i n g the r e a c t i o n . p y r i d i n e was  removed i n vacuo and the s o l i d residue was  30 ml. p o r t i o n s of b o i l i n g d i e t h y l ether. t r a c t was product l6  excess  extraced with three  The r e s i d u e from the ether ex-  r e c r y s t a l l i z e d from benzene, y i e l d i n g a c o l o u r l e s s c r y s t a l l i n e  (118.0 mg,  C H" 0 : 17  The  9.72%) which melted a t 74.0-76.0°.  C, 71.81}  4  H, 5.32,  Found:  The i n f r a r e d spectrum  C, 71.71}  Calculated for H, 5.96%.  showed two d i s t i n c t absorption bands i n the  r e g i o n of carbonyl s t r e t c h i n g frequencies one f o r the keto carbonyl (1682 ( i n benzoin i t s e l f  _ - = 1675  (1740 cm "*") i n equal i n t e n s i t y .  cm''") and one f o r the carbonate -  The NMR  spectrum  cm  carbonyl  of the compound was  also  recorded.  meso-Hydrobenzom D i - ( e t h y l c a r b o n a t e ) me s o-Hydr obenz oin (5 ml.) was  (2,15 millimole, 458.0 mg)  t r e a t e d with 1^08  chloroformate i n the same way from the ether e x t r a c t was  i n anhydrous p y r i d i n e  ml. (10.5 m£Llimoles, about 150% excess ) of e t h y l as i n the case of benzoin.  The product obtained  r e c r y s t a l l i z e d from methanol and y i e l d e d 125.8  mg.  (16.4%) of meso-hydrobenzoin-1»2-diethylcarbonate which melted a t 113.5115.5°. Found:  Calc. for C C, 67,28; The  2 ( )  H 0 : 2 2  6  C, 67.02}  H,  6.19.  H, 6.45%.  i n f r a r e d spectrum  showed only one carbonyl s t r e t c h i n g  corresponding t o the e t h y l carbonate absorption at 1740 trum of the sample was  (ii)  cm""". 1  The NMR  frequency spec-  a l s o recorded.  Aromatic N i t r a t e E s t e r s v i a D i r e c t E s t e r i f i c a t i o n .  c i s - and trans-1,2-Acenaphthenediol The c i s and trans-1,2-acenaphthenediols reported (68) (144) with 100% n i t r i c  Dinitrates. were n i t r a t e d as p r e v i o u s l y  a c i d - a c e t i c a c i d - a c e t i c anhydride i n  - 159 — 8.42 g  Nitrated  t-AD  below  0°C  12 4 6 g crude yellow oily product Extracted with boiling petroleum ether  9 0 g yell o w sohd extract washed  with cold  brown  oily  residue  MeOH  I  •  I I 4 3 g  white  J sohd  residue  37g  yellow  oily  i  extract  C h r o m a t o g r a p h y on S i 0  I  Early  fractions  Late  white 21 g j crystalline p r o d  (i) Chromat'd  (u) Chromat'd  i  2  fractions  yellow  oil C h r o m a t d on SiOo  on S1O2  on A l £ u Early  Pure d i n i t r a t e  •tract's  yellow  Recryst'd  from  petroleum  ether B  on A l 0 2  3  tract's  Middle t-ADDN  orange solid  oil  Chromat'd  fract's  Late  Recryst d  from  5  MeOH Byproduct  Yield  4 51g( 36.1 %>)  Byproduct Yield O 8 0 g  Yield- O 15 g  Mp-  980-1000°C  Mp:  oil  Mp- 210-215°C  TLC  M.ddle  TLC  High  FIGURE  43  R  f  Flow  Sheet  of  Separation  trans-1, 2-Accnaphthenediol  of  Rf  Nitration  (t-AD)  TLC • L o w  Products  R  f  from  - 160 -  molar proportions 4<.0:3#3:20 per mole d i o l at -15° to - 5 ° . c a t i o n of the o r i g i n a l procedure was  The only m o d i f i -  i n the workmg-up process.  Both  silicic  a c i d and alumina columns were used i n the p u r i f i c a t i o n of the d i n i t r a t e s ; i n the case of s i l i c i c a c i d a 1:1  ( v o l . / v o l . ) benzene-petroleum  ether  (b.p. 30-60°) mixture and i n the case of alumina, anhydrous d i e t h y l ether were used as e l u t m g  solvents.  columns 20 x 750 mm.  or 30 x 500 mm.,  sorbent r e s p e c t i v e l y were used.  For the products from 8.4 g, of d i o l , corresponding 300 or 400 ml of ad-  The separation procedure was  f a c t o r y f o r the two isomers and i s i l l u s t r a t e d f o r the nediol dinitrate  equally s a t i s -  trans-1,2-acenaphthe-  (t-ADDN) i n the form of a flow sheet i n F i g u r e 43.  u  Benzoin N i t r a t e To a mixture of a c e t i c a c i d a c e t i c anhydride ( l l . O  (5.6 ml) n i t r i c a c i d  (5.0 ml) and  ml) which was kept a t -10° with an i c e - s a l t bath a  s o l u t i o n of benzoin (12.32 g) i n a c e t i c anhydride (25 ml,) was added dropwise with vigorous s t i r r i n g ,  A f u r t h e r 20 ml. p o r t i o n of a c e t i c anhydride  was added and the mixture, a f t e r 20 minutes t o t a l r e a c t i o n time, was  poured  i n t o ice-water which p r e c i p i t a t e d a crude product (13.59 g, 91.0%).  The  c o l o u r l e s s s o l i d was twice r e c r y s t a l l i z e d from a benzene-petroleum (30-60°) mixture. Calc. for C  1 4  The f i n a l product (5.30 g, 35.5%) melted at 77-78°.  H 0 N: n  4  ether  N, 5.45.  T h i n - l a y e r chromatography  Found: (M-3,  N, 5.47%. S-1, R-2)  i n d i c a t e d t h a t the  mother l i q u o r s from the r e c r y s t a l l i z a t i o n contained some r i n g - n i t r a t e d product, while the c r y s t a l l i n e n i t r a t e ester gave only one spot which i n d i c a t e d the absence of by-products.  The s o l i d state i n f r a r e d  showed a broad t r i p l e t a b s o r p t i o n a t 1643, cated that the most intense band a t 1672  1672  and 1695  spectrum  cm ^ and  indi-  cm ^ probably represented the  - 161 -  carbonyl absorption (benzoin absorbed a t 1675 cm  ) . The NMR spectrum of  the sample was also recorded. me s o-Hydr obenz oin D i n i t r a t e meso-Hydrobenzom (21.0 g) was n i t r a t e d as described above f o r 30 minutes and the temperature was maintained between -12 and  +2°C. The mixture  was t r a n s f e r r e d t o ice—water and l e f t overnight. The crude product (32.28 g, 112%) was separated by f i l t r a t i o n and was r e c r y s t a l l i z e d from benzene-petroleum e t h e r .  The n e a r l y c o l o u r l e s s c r y s t a l l i n e product was chromatographed  on a 30 x 500 mm. alumina column, eluted with a 1:1 mixture of benzenepetroleum ether ( 3 0 - 6 0 ° ) and was f i n a l l y r e c r y s t a l l i z e d from the same s o l v e n t . The y i e l d was 17.20 g, (57.7$)}  m.p. 1 4 8 . 5 - 1 4 9 . 5 ° .  The s o l i d state i n f r a r e d  spectrum showed c h a r a c t e r i s t i c n i t r a t e absorptions.  C a l c . f o r C, .H^_0,N_:  14 12 6 2  r  C, 55*26;  H, 3.98;  N, 9,21.  Found:  C, 55.46;  H, 3.91;  N, 9.11%.  Hydrogenolysis of 47.2 mg. of the d i n i t r a t e i n 25 ml. of absolute ethanol w i t h 48.6 mg. of palladium-charcoal c a t a l y s t a t 60 p s i of hydrogen f o r 3.5 hours produced the parent me s o-hydr obenz o m which was i d e n t i f i e d by i t s m e l t i n g point ( 1 3 7 - 1 4 0 ° ) , TLC (M-3, S-3, R - l ) , and i n f r a r e d  spectrum.  dl-flydr obenz o m D i n i t r a t e .  dl-Hydrobenzom  (21.0 g) was n i t r a t e d as f o r the meso- isomer.  The crude product (25.5 g, 85.6%) was r e c r y s t a l l i z e d from benzene~petroieum ether ( 3 0 - 6 0 ° ) mixture and chromatographed  on alumina.  Further r e c r y s t a l l i z e d  from benzene-petroleum ether y i e l d e d 9.07 grams (30.4%) of pure product which melted a t 1 0 5 . 5 - 1 0 7 o O ° . n i t r a t e absorptions.  The i n f r a r e d spectrum showed c h a r a c t e r i s t i c  C a l c . f or C, .R.O^N-:  N, 9.21.  Found;  9.17%.  14 12 6 2 Hydrogenolysis of 47.7 mg of the d i n i t r a t e as above produced thp parent dl-hydrobenzom  which melted a t 9 9 - 1 0 5 ° .  T h m layer  chromatography  - 162  -  and the i n f r a r e d spectrum i n d i c a t e d the presence of only traces of i m p u r i t i e s .  (ni)  Aromatic N i t r a t e E s t e r s v i a Exchange Reactions. Benzyl N i t r a t e  Benzyl n i t r a t e was  prepared from f r e s h l y d i s t i l l e d reagent  benzyl c h l o r i d e according to F e r r i s and co-workers (p5). was  d i s t i l l e d i n vacuum from s o l i d s i l v e r n i t r a t e .  The  The  grade  crude product  e a r l y f r a c t i o n con-  t a i n e d a t r a c e amount of b e n z y l - c h l o r i d e but the bulk of the m a t e r i a l d i s t i l l e d at 59-62°/0.37mm. and gave the c o r r e c t i n f r a r e d and NMR pure b e n z y l . n i t r a t e * The reported b o i l i n g p o i n t was  spectra f o r  45/0.5 mm.  (43).  meso-Hydrobenzoin D i n i t r a t e  According to F i s h b e m (36) meso-2,3-dibromobutane gave d l - 2 3 1  dinitroxy-butane with s i l v e r n i t r a t e v i a Walden i n v e r s i o n .  Thai e f f e c t of  s i l v e r n i t r a t e on meso-dibromo s t i l b e n e i n a c e t i c a c i d s o l u t i o n was  studied  by von Walter and W e t z l i c h (207)  i n 1900 who  claimed i t produced hydrobenzoin  d i n i t r a t e which melted at 132°.  Since no sterochemical assignment was  pro-  vided by von Walter and W e t z l i c h and the d i n i t r a t e s synthesized by d i r e c t e s t e r i f i c a t i o n i n t h i s work melted at d i f f e r e n t temperatures, t h e i r synthesis i n both a c e t i c a c i d (a)  (a) and a c e t o n i t r i l e  meso-Dibromostilbene (3.400 g, m.p.  pended i n a c e t i c a c i d (100 m l ) 0  (4.100 g, 50$ excess) was  The  sus-  -Silver n i t r a t e and  after  added dropwise to the hot bromide susc o l o u r l e s s suspension g r a d u a l l y changed  to the pale yellow colour of s i l v e r bromide. was  (b) s o l v e n t s .  d i s s o l v e d i n d i s t i l l e d water (5 ml.)  pension with vigorous s t i r r i n g .  repeated  251.0-252,5°) was  at the b o i l i n g p o i n t .  d i l u t i o n with a c e t i c a c i d (5 ml.) was  we  A f t e r 15 minutes the  f i l t e r e d on a s i n t e r e d g l a s s funnel and the cloudy f i l t r a t e was  mixture poured  - 163 -  i n t o d i s t i l l e d water (500 ml,) and the aqueous s o l u t i o n was placed i n the refrigerator.  The p r e c i p i t a t e which formed a f t e r 10 hours was  collected  (1.609 g, 52.6$) and r e c r y s t a l l i z e d from 50 ml. of petroleum ether (30-60°). The c r y s t a l s  (695.8 mg, 22.8$) melted at 139,5-142.0° and since TLC  (M-3,  S—1, R—l) i n d i c a t e d the presence of a number of lower-running i m p u r i t i e s they were f u r t h e r p u r i f i e d by t h i c k - l a y e r chromatography (M-5, S - l ) ,  The  f i n a l product obtained melted a t 146-148° and was shown t o be i d e n t i c a l t o authentic meso-hydrobenzoin d i n i t r a t e by i n f r a r e d spectroscopy and TLC (M-3, S - l , R - l ) . (b)  meso-Dibromostllbene (3.402 g) was suspended i n a c e t o n i t r i l e  (50 ml.) a t the b o i l i n g p o i n t . dissolved m  Silver nitrate  (4.100 g, 50$ excess) was  a c e t o n i t r i l e (5 ml.) and added to the suspension.  minutes the mixture was f i l t e r e d  A f t e r 15  and the f i l t r a t e was evaporated _in vacuo.  The brown, crude product (4.94 g) was extracted w i t h 4 x 60 ml. of hot petroleum ether (65-110°) and then with two portions of 60 ml. of hot methanol. The residue from the methanol e x t r a c t was r e - e x t r a c t e d with hot petroleum ether and the petroleum ether e x t r a c t s were combined and evaporated to give 1.602 (52.6$) of s o l i d product which was r e c r y s t a l l i z e d from 80 ml. of petroleum ether (30-60°) and melted at 140-146°.  Further p u r i f i c a t i o n by t h i c k - l a y e r  chromatography y i e l d e d me s o-hydr obenz oin d i n i t r a t e which melted at 145-147° and had the c o r r e c t i n f r a r e d spectrum and R^, values (TLC, M-3, The parent a l c o h o l , me s o-hydr obenz oin  f  S-l, R-l).  was recovered by hydros  g e n o l y s i s of the d i n i t r a t e and was i d e n t i f i e d by i t s melting point 139.5°, reported m.p  0  138.5°) (201) and i n f r a r e d spectrum.  (137.0—  g,  TABLE  XXX  Attempted Cyclic  Sample  Carbonates  (mg)  Syntheses  and  Nitrate  Esters  from  Ethylcarbonatcs  * Solvent  of A r o m a t i c  M P CC)  Reaction AgN0 (mg)  (ml)  Hit -flt  3  Condition Ti me Temp. (hrs) C O  Starting Material  Expectc d Nitrate Ester  Produc t Obtained  O it  o  p  H )  ( -H  6u  5.4  5.0  14.4  60  20  43.0  5 0  179  Bp  3  50 7  50  Bp  3  231  128-130  228-234  77-78  76-78  cis-1,2-Acenaphthene di ol C a r b o n a t e (LVD y2 5 H  °>o  0Q  74-76  B e n z o i n E t h y l c a r b o n a t e (LVll) 592 92 5 H  H  o=c  b  H-C  c=o  d  C--H  0 0  meso-Hydrobenzoin Di ( E t h y l c a r b o n a t e ) (LVIII) * Acctomtrile "** Procedure  according  to  Boschan  142  (37)  1135-115.5  148 5-149.5  116.5-118.5  - 165 -  Attempts  t o Exchange Carbonate Groups f o r N i t r o x y Groups  The c y c l i c carbonate of c i s - l , 2 - a c e n a p h t h e n e d i o l (LVl) and the e t h y l carbonate d e r i v a t i v e s of benzoin (LVII) and me s o-hydr obenz o i n  (LVIIl)  were t r e a t e d with s i l v e r n i t r a t e i n a c e t o n i t r i l e s o l u t i o n s as d e s c r i b e d by Boschan (37) f o r the replacement group.  of the _g-chloroformate group by the _o-nitro  The d e t a i l s of these experiments  p o i n t s and R  f  a r e shown i n Table XXX.  The melting  values (TL^, M-3, S-1, R - l ) of the products i n d i c a t e d the  recovery of the unreacted carbonates.  II, A,  Analyses,  M e l t i n g P o i n t Determinations.  M e l t i n g p o i n t s were observed microscope  (-0*5 ) with a hot stage p o l a r i z i n g  (Wetzlar, No, 48114, E r n s t L e i t J ? , Germany).  B«,  Elementary Analyses.  Carbon, hydrogen, and Dumas n i t r o g e n analyses were made by Mrs. A. E . A l d r i d g e , M i c r o a n a l y t i c a l Laboratory, Department of Chemistry, U n i v e r s i t y of B r i t i s h  Columbia,,  III. A,  Spectra  U l t r a v i o l e t Spectra (UV)  A l l u l t r a v i o l e t s p e c t r a were taken on Cary r e c o r d i n g s p e c t r o photometers (Model 14 or Model 11) m l  cm. quartz c e l l s i n one of the  following solvents: Methyl a l c o h o l  Absolute  Ethyl alcohol  95% Reagent  D i e t h y l ether  Anhydrous, peroxide f r e e  Benzene  Absolute, oxygen f r e e  Hexane  Spectra grade  - 166  -  Some of the measurements were made by Mrs. M. Z e l l , Spectroscopic  Laboratory,  Department of Chemistry, U n i v e r s i t y of B r i t i s h Columbia.  B»  I n f r a r e d Spectra  (IR)  A l l i n f r a r e d s p e c t r a were recorded on a P e r k i n Elmer No. 21 s p e c t r o -prJI<2.t's meter i n potassium  bromide wmHnwry or i n solvent-compensated cyclohexane s o l u -  t i o n s by Mrs. M. Z e l l . Spectroscopic Laboratory, Department of  Chemistry.  U n i v e r s i t y of B r i t i s h Columbia, C.  E l e c t r o n Spin Resonance Spectra  (ESR)  E l e c t r o n s p i n resonance s p e c t r a were recorded on a V a r i a n V-4500 spectrometer,  equipped with a 1© inch magnet and a 100 Kc f i e l d modulator.  The c a v i t y used contained s l o t s f o r entry of u l t r a v i o l e t l i g h t which permitted simultaneous  i r r a d i a t i o n w i t h ESR measurements.  Most of the s p e c t r a were  taken at room temperature (^300°K) but f o r some experiments an 11 mm. quartz Dewar v e s s e l was temperature (77°K).  o.d.  i n s e r t e d i n the c a v i t y f o r studies at l i q u i d n i t r o g e n  UV sources were e i t h e r a G.E.-H85-A3 medium pressure  mercury arc lamp or a more powerful G.E.-A-H6 h i g h pressure mercury arc lamp. The u n f i l t e r e d l i g h t was  focused i n the c a v i t y by means of a quartz lens  system and the f i n a l p o s i t i o n of the lamp f o r maximum l i g h t i n t e n s i t y  was  determined with the a i d of a p h o t o c e l l i n s e r t e d i n place of the sample to be  irradiated.  D,  Nuclear Magnetic Resonance Spectra  (NMR)  The proton resonance s p e c t r a were taken on a V a r i a n A-60 60 Mc. h i g h r e s o l u t i o n spectrometer  m  deutero-chloroform,  analytic  acetone or t r i —  f l u o r o a c e t i c a c i d as s o l u b i l i t y permitted with tetramethyl s i l a n e as i n t e r n a l or e x t e r n a l r e f e r e n c e .  The  s p e c t r a WBre recorded by Mrs. E . M, B r i o n ,  - 167  -  Spectroscopic Laboratory, Department of Chemistry, U n i v e r s i t y of B r i t i s h Columbia.  IV.  Chromatography.  Conventional wet—packed column chromatography was t i v e procedures 8.0 mm.)  was  Thin-layer  used i n prepara-  on a macro scale while t h i c k - l a y e r chromatography (0,5 t o  used i n the i s o l a t i o n of semi-micro amounts of pure compounds*  chromatography (TLC, 0.25-0.5 mm.)  was  used f o r q u a l i t a t i v e  a n a l y s i s and the i s o l a t i o n of micro q u a n t i t i e s of r e a c t i o n products*  Colour-  l e s s compounds were detected on chromatograms by the use of s p e c i f i c spray reagents or by examination u n d e r ' u l t r a v i o l e t light.(Chromato-Vue,  Ultra-  v i o l e t Products Inc., San G a b r i e l , C a l i f o r n i a ) before and a f t e r the a p p l i c a t i o n of spray reagents. The adsorbing media (M), solvents described  (S) and spray reagents  (R) are  i n Tables XXXI* XXXII, XXXIII r e s p e c t i v e l y .  Table XXXI Adsorbents  and Supporting M a t e r i a l s f o r Chromatography  No.  Adsorbent  Used as  M-l  S i l i c a g e l (BDH " f o r chromatography" No. 311270)  Column  M-2  Alumina (E. Merck "Aluminum Oxide" No. 71707)  Column  M-3  S i l i c a Gel G. Darmstadt•)  Co.,  TLC  M-4  Aluminum Oxide-G. Co., Darmstadt.)  (E« Merck and  TLC  M-5  S i l i c i c a c i d ( M a l l i n c k r o d t , 100 mesh)-Plaster of Paris*-Water (4:1:8)  ( E Merck and 0  Ref.  (62)  TLC and Thick-layer  (105) (208)  * Gypsum, Lime and A l a b a s t i n e  Company Limited, Vancouver,  B.C.  - 168 -  Table XXXII Solvents f o r Chromatography  No.  * **  R a t i o of Volumes  Solvents  Ref.  S-1  Benzene—petroleum ether*  1:1  ——  S-2  Benzene-petroleum e t h e r * *  3:1  (209)  S-3  Benzene-diethylether  4:1  S-4  Benzene-ethylacetate  1:1  S-5  Benzene-acetic a c i d  S-6  Benzene  S-7  Petroleum e t h e r — — d i e t h y l  S-8  Petroleum ether*-*—chloroform  S-9  Chloroform  S-10  Methylene c h l o r i d e  49:1  ether**  (210)  9:1 1:1  o b.p. range 30-60 C. o b.p. range 60—80 C,  Table XXXIII Spray Reagents f o r Chromatography  No.  Reagent  Ref.  R-l  5% ( v o l / v o l ) Fuming n i t r i c a c i d i n cone. sulfuric acid  (105)  R-2^  1% (wt/vol)  Diphenylamine i n 95%> ethanol  (21l)  R-3  1% (wt/vol)  Potassium permanganate  (212)  2% (wt/vol)  aqueous sodium carbonate  m  - 169 -  V. A,  Photolyses  L i g h t Sources and  Apparatus  Three lamps were used as l i g h t sources throughout these experiments. G.E.  - H85J-A3. a medium pressure mercury arc lamp, was used f o r the  p r e l i m i n a r y experiments and f o r some of the ESR measurements.  The lamp was  surrounded w i t h a copper c o o l i n g c o i l and housed i n a sheet s t e e l (100 x 100 x 150 mm.) f o r the l i g h t beam.  box  t i n n e d on the inner surfaces with a 10 x 25 mm.  window  The f a c t o r y report of energy d i s t r i b u t i o n f o r the lamp  together with the observed r e l a t i v e i n t e n s i t i e s are shown i n F i g u r e 44. G.E.-A -H6,  a h i g h pressure mercury arc lamp, was used f o r some of  the ESR measurements since i t had a greater output i n the absorption r e g i o n (2600-3000 1) of the n i t r o x y group. p l o t t e d against wavelength  The f a c t o r y r e p o r t f o r power output i s  i n F i g u r e 45.  Hanovia - 8A36 — 00066, a h i g h pressure mercury arc lamp was  used  f o r a l l the r e a c t i o n k i n e t i c measurements and p r e p a r a t i v e i r r a d i a t i o n experiments.  The lamp was placed i n s i d e of a t e s t tube-shaped Corex  filter  (Hanovia, No. 513-27-114) and t h i s i n t u r n was placed i n s i d e a q u a r t z , waterjacketed w e l l , thus the l i g h t was  f i l t e r e d throughout a l l experiments  by  successive l a y e r s of Corex g l a s s , q u a r t z , d i s t i l l e d water, and q u a r t z . The q u a n t i t a t i v e data on the lamp output are summarized i n F i g u r e 46.  F i g u r e 46c. shows the s p e c t r a l d i s t r i b u t i o n as observed on a Beckman  DU spectrophotometer, while F i g u r e 46b. shows the power output i n u n i t s of watts and c a l o r i e s / s e c .  These c a l i b r a t i o n s , according to the f a c t o r y r e p o r t ,  were taken through a quartz water c e l l with an Ag-Bi thermopile, c a l i b r a t e d against a standard lamp (National Bureau of Standards).  The measurement was  performed on s e v e r a l lamps and thus represents a good average f o r t h i s lamp. No doubt the a c t u a l output values v a r i e d from lamp t o lamp but are probably  — 170 — 80-  0 40 '  ,,069^064,075,162 . * H  H«  0 77  042  W4  H<  348  | U  >|(  0 39wqtts.  60 +  C  :40  c d  201  2600  2800 FIGURE  3000 44  FIGURE Pressure  3200  Reported  Distribution  for  45  i  3400  3600  Power  Output  and  GE-H85-A3  Medium  Pressure  Reported  Mercury-Arc  Power Lamp  Output  3800  Observed  for  4 0 0 0 A (A)  Spectral  Mercury-Arc  GE-A-H6  Lamp  High  — 171 (a) CALCULATED NUMBER OF QUANTA (me/sec) vs WAVELENGTH (A) EXPANDED VERTICAL SCALE (4X) OF REGION 2200 — 2900  QUARTZ  4 J  '  1  l I I i ! 1  Jllilll  2500  £  IOO-  2000  2500  WAVELENGTH  (b) REPORTED POWER OUTPUT (watts) vs WAVELENGTH (A) 40-i je363432-  isl  4  .  2000  2500  3000  (c) OBSERVED T %  3500  4000  4500  5000  5500  6000  TRANSMITTANCE (%) vs WAVELENGTH (A) EXPANDED VERTICAL SCALE (50X) OF REGION 2 5 0 0 — 29 "iO <  too90' 80-  5500  Ev / quantum  I •  1  150 140  F.g 46  BY  • ' > I • 130 120  '  110  LIGHT ENERGY EMITTED HANOVIA 100 WATT HIGH PRESSURE  MERCURY ARC LAMP  &  - 172 -  r e l i a b l e w r t h m -10$. F i g u r e 46a. shows the output i n number of quanta per second versus wavelength.  The f i g u r e s p l o t t e d were c a l c u l a t e d from the f a c t o r y r e p o r t om  the f o l l o w i n g b a s i s : (l)  Given the t o t a l energy output (e, c a l / s e c ) f o r each wavelength.  ( i i ) The energy (6 ) of one i n d i v i d u a l photon i s £ = h <3 *= ~  ( e r g s / p a r t i c l e ) and the energy of an  Avogadro number of photons ( e i n s t e m ) i s given by g E - N  — r - (ergs/mole) = ~ — - , T T Mem) -Jo  (cal/mole)  }  (m)  The r a t i o of values thus obtained i n (I) and ( i i ) gave the number of molequanta/sec £ E  / c a l / c a l \ _ _e / mole \sec / moles] E V sec  Fhotoreactor.  ^ _  einstem \ sec J  The apparatus was constructed lp^ Pyrex glass s u r -  rounding an Hanovia quartz immersion w e l l as i n d i c a t e d m  F i g u r e 47.  The  thickness of the s o l u t i o n which surrounded the lamp was 0.665 cm.  A Teflon-  coated magnet bar s t i r r e r and helium gas stream provided e f f i c i e n t  circu-  l a t i o n of the i r r a d i a t e d s o l u t i o n .  The i n e r t gas stream was passed succes-  s i v e l y through a l k a l i n e p y r o g a l l o l and S u l f u r i c a c i d wash b o t t l e s , then a U-shaped s i l i c a g e l column and f i n a l l y i t was saturated with the vapours of the solvents used f o r the p h o t o l y s e s . The s a t u r a t i o n was necessary i n order to prevent appreciable solvent l o s s during prolonged i r r a d i a t i o n s .  A hard  polyethylene tubing was used f o r the connection between the solvent wash b o t t l e and the photoreactor since Tygon tubing was attacked by benzene vapour which d i s s o l v e d some o i l y m a t e r i a l ( p l a s t i c i z e r ? ) from the t u b i n g .  The gas  flow was s t a r t e d one-half hour p r i o r t o the p h o t o l y s i s i n order t o purge  Fig 4 7  PHOTO REACTOR  - 174 -  d i s s o l v e d oxygen and was maintained continuously during the i r r a d i a t i o n . Constant temperature  (- 0.05°) was maintained i n the r e a c t o r by  c i r c u l a t i n g c o o l i n g water from an e x t e r n a l bath through the water jacket of the immersion w e l l .  The i n l e t temperature was 23.70° and the o u t l e t  temperature was 24.70° so t h a t the average of the two, 24.20°, was taken as the r e a c t i o n temperature and t h i s was a l s o checked from time to time by measuring the s o l u t i o n temperature with the same thermometer.  To ensure  thermal e q u i l i b r a t i o n , the c o o l i n g water c i r c u l a t i o n was s t a r t e d 30 minutes before an i r r a d i a t i o n experiment. For c e r t a i n experiments the calcipm c h l o r i d e tube (Figure 47)  was  replaced by a set of t r a p s cooled at various temperatures t o separate and r e t a i n gaseous r e a c t i o n products.  B« Experiment No. 1  P r e l i m i n a r y Experiments. A 0.1 M s o l u t i o n of trans-1,2-acenaphthenediol  d i n i t r a t e i n benzene (20»9g.m 0.75 ml.) m a  stoppered quartz t e s t tube was  purged with n i t r o g e n and placed i n a Beckman DU spectrometer. was  The sample  i r r a d i a t e d f o r successive 2 hour periods with the 3660, 3140, and 3030 A*  bands of a GE -H85  -A3 UV lamp.  No colour formation was  observed m  the  s o l u t i o n at the above wavelengths e i t h e r because they were too long or be— cause the i n t e n s i t y of the l i g h t a f t e r passing through the monochromator was too low.  An a d d i t i o n a l 2 hour i r r a d i a t i o n with the t o t a l output of the lamp  at 20 cm. distance produced a y e l l o w s o l u t i o n i n d i c a t i n g photodecomposition. The s o l u t i o n was analysed by TLC  (M-5, S-1, R - l ) and the p a t t e r n  of spots confirmed t h a t the n i t r a t e e s t e r had been photolysed.(Figure 4 8 ) . The blue f l u o r e s c e n t spot "C" was removed from a t h i c k - l a y e r chromatogram and deposited as a f i l m on a sodium c h l o r i d e p l a t e and the IR spectrum  was  — 175 —  Colour Under  Symbol  UV  0.8-I  F  0.7-  After Spray Rea.  br- a bl  w— f  E 0.6  w  B 10  —f  1  graded seal O.D.8 m m  0.4  150 0.2  O.D. 4  bl-f w-  B A  FIGURE  TLC  ( M - 5 , S-1 , R - 1 )  trans-1, 2-Acenaphthenediol Photolysed  gr br  y-a  - 0 48.  f  in B e n z e n e  of  Dinitrate  Solution.  FIGURE  4 9 . ESR  Scale  2:1  Tube  -si  1G53 FIGURE  1619 50.  1464 Solid Its  State  Infrared  Photolysis  Spectra  Products.  (  of  1285 trnns-1,2-Accnaphthencdiol t-ADDN:  Dinitrate  fluorescent  and  photolysis  One  of  Product ( O ) .  - 177 -  recorded (Figure 50).  The sample was f r e e of the o r i g i n a l n i t r a t e ester  according to the spectrum. Experiment No, 2  Two  oxygen-free samples  (0.01 M) of trans-1,2-  acenaphthenediol d i n i t r a t e i n benzene were i r r a d i a t e d simultaneously with the  GE - H85  -A3 lamp i n l c m , quartz and Corex c e l l s at a distance of about  20 cm. f o r a period of 12 hours,,  A s i m i l a r 0.1 M s o l u t i o n was  with the same lamp f o r the same time i n the ESR and sealed tube (Figure 4 9 ) .  irradiated  spectrometer i n a degassed  F i g u r e 51 shows the chromatographic  analysis  of the three samples. Experiment Nos, 3 and 4 e s t e r s (Table  S o l u t i o n s (l.O ml., 0.01 M) of s i x n i t r a t e  XX ) i n benzene i n small quartz t e s t tubes were purged with  n i t r o g e n and i r r a d i a t e d i n close contact w i t h the water cooled Hanovia 8A36 - 00066 lamp f o r a t o t a l of 9 hours.  A l i q u o t s were taken of the s o l u -  t i o n s at 0, 0.5,  1.5, 4,0, and 9.0 hours and examined by TLC  S-10)  18  (Figures  and  19  and Table  XX  )„  and  S i m i l a r experiments were  c a r r i e d out i n degassed, sealed ESR tubes (0.1 ml., 0.1 M.) opening, the c o l o u r l e s s gas i n the tubes became yellow-brown  C.  (M-3, S-6,  f o r 22 hours, on (Table XX).  K i n e t i c Experiments.  I r r a d i a t i o n s f o r measured time i n t e r v a l s were c a r r i e d out i n the photoreactor on s o l u t i o n s c o n t a i n i n g 0«02 moles of n i t r o x y group per l i t e r . The solvent was removed from the photolysed s o l u t i o n under reduced pressure, the  residues were taken up i n acetone, a few grams of s i l i c a g e l was added  and the acetone was  evaporated.  The p h o t o l y t i c products adsorbed on the  s i l i c a g e l were t r a n s f e r r e d t o 20 x 500 mm.  columns packed with s i l i c a g e l  and the chromatograms were developed with one l i t e r of a mixture of p e t r o leum ether (30-60°) and benzene ( 3 : l ) which removed the unreacted n i t r a t e e s t e r s and these were recovered on evaporation of the eluate f r a c t i o n s and  - 178 -  U n d e r UV  brown absorption  white f I uoresc.  blue fluorescence  white •f I uorescence brown absorption bl-fl br- a y -a I FIGURE Dinitrate  II 51.  TLC  after  (M-5,S-6)  Photolysis  I. in Q u a r t z C e l l (0.01 M ) III. in C o r e x  III  C e l l (0.01 M )  in II.  of  trans 1 2 Acenaphthencdiol  Benzene Quartz  Solution. ESR  Tube  (0.1  M)  - 179  -  weighed. The columns were then e l u t e d with methanol t o remove the products which were recovered i n a s i m i l a r manner. 1,2-acenaphthenediol lowing: (iv)  (i)  In the case of the  d i n i t r a t e s the order of e l u t i n g solvents was the  petroleum ether-benzene  methanol.  photo-  (3si),  ( i i ) benzene,  fol-  ( i i i ) chloroform,  The unreacted n i t r a t e e s t e r s were removed by the f i r s t solvent  and solvents ( i i ) to ( i v ) removed other p h o t o l y s i s products.  A f t e r the i r -  r a d i a t i o n s of me s o-hydr obenz o i n d i n i t r a t e and benzyl n i t r a t e i n ethanol s o l u t i o n the evaporated a l c o h o l was from i t as the corresponding  D.  c o l l e c t e d and v o l a t i l e aldehydes were i s o l a t e d  2,4-dinitrophenylhydrazones.  I s o l a t i o n and I d e n t i f i c a t i o n of Photoreaction Products, (a)  Products from 1,2-Acenaphthenediol  Dinitrates  I r r a d i a t e d i n Benzene S o l u t i o n . The f r a c t i o n s obtained from the k i n e t i c i r r a d i a t i o n experiments  by  e l u t i o n of the columns with benzene and chloroform were combined (TLC showed s i m i l a r patterns) and evaporated at reduced pressure. m a t e r i a l was  The acetone s o l u b l e  f i l t e r e d , evaporated under n i t r o g e n and d r i e d _in vacuo f o r a  week to remove t r a c e s of acetone and then t r e a t e d with the p - n i t r o p h e n y l — hydrazine reagent.  Two  crops of the dark red c r y s t a l s were i s o l a t e d which  were s i m i l a r i n appearance but the f i r s t crop i s o l a t e d from the trans-isomer melted at 225-227°, c l o s e t o the r e p o r t e d m e l t i n g point of the b i s - p - n i t r o phenylhydrazone  of 1,8-naphthalene dialdehyde  (227°) (213) while the c o r r e s -  ponding f i r s t crop from the c i s - d i n i t r a t e melted over the range 140-190° i n d i c a t i n g a mixture.  The second crops o r i g i n a t i n g from the two  isomers  melted at 174-180° and 174—181° r e s p e c t i v e l y i n d i c a t i n g t h a t they might be the same compound.  - 180  -  The methanol eluate from the columns were evaporated  and the r e s i d u e s  a f t e r standing open to the a i r f o r s e v e r a l weeks d i d not r e d i s s o l v e completely i n methanol.  The methanol-soluble  portions contained n i t r o p h e n o l s (TLC) while  the i n s o l u b l e p o r t i o n s contained f l u o r e s c e n t m a t e r i a l .  The  methanol-insoluble,  yellow s o l i d s were e x t r a c t e d with b o i l i n g saturated aqueous sodium bicarbonate s o l u t i o n and the a l k a l i n e e x t r a c t s a f t e r c o o l i n g were a c i d i f i e d with  sulfuric  a c i d to pH 1.  The c o l o u r l e s s c r y s t a l l i n e products which p r e c i p i t a t e d were  1,8-naphthalic  acid  (TLC, M-3,  S-5, yellow-white  fluorescence of under  UV)  which melted at 271-272° f o r the sample which o r i g i n a t e d from the c i s d m i t r a t e and a t 257-272° f o r the sample which o r i g i n a t e d from the t r a n s lsomer. was  The melting p o i n t of a r e c r y s t a l l i z e d commercial sample of the a c i d  271-272°, while the reported value was  confirmed the The  270° (213).  The  infrared spectra  identity. sodium b i c a r b o n a t e — i n s o l u b l e p o r t i o n s of the residues were  d i s s o l v e d i n e t h y l acetate and t r e a t e d with c h a r c o a l . t i o n s obtained showed the same two yellow-white (TLC) i n about equal i n t e n s i t y . value of 1,8-naphthalic  One  The c o l o u r l e s s s o l u -  and blue f l u o r e s c e n t spots  of these spots (yellow-white) had  the  a c i d while the i d e n t i t y of the other, blue  f l u o r e s c e n t , lower-R^ spot remained unknown. (b)  Products from me s o-Hydr obenz o i n D i n i t r a t e I r r a d i a t e d i n Benzene S o l u t i o n .  A s o l u t i o n of meso—hydrobenzom d i n i t r a t e (200 ml.) was evaporated  photolysed f o r 12 hours at 24.5°.  (608,3 mg)  i n benzene  The benzene s o l u t i o n  i n vacuo y i e l d i n g a p a r t i a l l y c r y s t a l l i n e product  (569.5  which contained unreacted n i t r a t e e s t e r and p h o t o l y s i s products. v o l a t i l e compounds were d i s t i l l e d from a b o i l i n g water bath at 10  was  mg)  The _2  mm.  - 181 -  pressure i n a m i c r o d i s t i l l a t i o n apparatus into a r e c e i v e r cooled i n d r y i c e acetone.  The yellow d i s t i l l a t e had a very intense odor of benzlaldehyde and  TLC i n d i c a t e d the presence of _o-nitrophenol as w e l l . To one p o r t i o n of the d i s t i l l a t e 2,4-dinitrophenylhydrazine reagent was  added and caused an immediate p r e c i p i t a t i o n of a s o l i d product which was  f i l t e r e d o f f , washed with methanol and r e c r y s t a l l i z e d twice from e t h a n o l . The compound melted a t 237.5-238.5°C; dmitrophenylhydrazone  N, 19.57.  Found:  was 237°C  the reported m.p, f o r benzaldehyde 2,4—  Calc. for C  C, 54.23) H, 3.79;  H^C^N s C, 54.5?  H, 3.52$  N, 19i.23$.  Another p o r t i o n of the d i s t i l l a t e was exposed t o a stream of oxygen gas i n order t o oxidize the benzaldehyde  i n the mixture t o benzoic a c i d . The  product was then t r e a t e d with d i s t i l l e d water (100 ml.) a c i d i f i e d with s u l f u r i c a c i d and the j>-nitrophenol was steam d i s t i l l e d i n t o 25 m l . of 2N sodium hydroxide s o l u t i o n .  The y e l l o w d i s t i l l a t e was a c i d i f i e d with s u l f u r i c a c i d  and e x t r a c t e d with e t h e r  0  The d r i e d (sodium s u l f a t e ) ether s o l u t i o n y i e l d e d  a small amount of y e l l o w o i l y s o l i d which contained _o-nitrophenol and benzoic a c i d (TLC).  Calc. for C ^ C ^ N :  N, 10,07$.  Found:  N, 4.57$.  The residue from the steam d i s t i l l a t i o n was e x t r a c t e d with ether and the s o l i d residue recovered was r e c r y s t a l l i z e d from water. y e l l o w c r y s t a l s melted at 117 - 1 2 0 ° . was  1 2 1 ° (197).  The NMR spectrum  t h a t of an authentic sample. Found:  C, 67.87;  The pale  The reported m.p, f o r benzoic a c i d  ( i n deuterochloroform) was i d e n t i c a l with  C a l c , f o r C^H^Og:  C, 68,84;  H, 4.95.  H, 5.67$.  The products from s e v e r a l other photodecomposition  experiments on  meso-hydrobenzoin d i n i t r a t e i n benzene s o l u t i o n were worked up as d e s c r i b e d above by column and t h i c k — and t h i n - l a y e r chromatography i n attempts t o i s o l a t e and i d e n t i f y other compounds o r i g i n a t i n g from the benzene s o l v e n t .  - 182  -  Although s e v e r a l pure f r a c t i o n s were obtained, the q u a n t i t i e s of the s e v e r a l compounds i n v o l v e d were so small as t o preclude p o s i t i v e i d e n t i f i c a t i o n .  In  general these products appeared t o be n i t r o p h e n o l s s i m i l a r t o those l i s t e d i n Table XXVTII as judged from t h e i r behaviour on chromatograms, c o l o u r , s e n s i t i v i t i e s toward (c)  o x i d i z i n g reagents  (R-3) and i n f r a r e d s p e c t r a (Figure 24).  Products from meso-Hydrobenzoin D i n i t r a t e I r r a d i a t e d i n Ethanol S o l u t i o n .  A 0.02  M s o l u t i o n of the d i n i t r a t e was  10 hours at 24.2°C.  The a l c o h o l was  i n a r o t a r y evaporator which was a water condenser  d i s t i l l e d o f f under reduced pressure  equipped with a solvent t r a p followed by  and r e c e i v e r kept at dry ice-acetone temperature.  solvent t r a p , which was benzaldehyde  photolysed f o r a p e r i o d of  The  at room temperature, r e t a i n e d the high b o i l i n g  i d e n t i f i e d as the 2,4—dinitrohenylhydrazone.  The sample  melted a t 238-239° ( c f . Table XXVII). The UV spectrum of the a l c o h o l s o l u t i o n trapped a t ca.-80° showed the c h a r a c t e r i s t i c band f o r acetaldehyde. (Figure 52). phenylhydrazme reagent was  2,4-Dimtro-  added and the yellow p r e c i p i t a t e obtained a f t e r  long standing at room temperature was  twice r e c r y s t a l l i z e d from methanol.  The product was the 2,4—dinitrophenylhydrazone of acetaldehyde;  m.p.  164.5-165.5° ( c f . Table X X T I l ) .  (d)  Products from Benzyl N i t r a t e I r r a d i a t e d i n Ethanol S o l u t i o n .  Three s o l u t i o n s each c o n t a i n i n g 30.6 mg.  of benzyl n i t r a t e i n  200 ml. of absolute ethanol were i r r a d i a t e d f o r 4, 7, and 10 hours r e s p e c t i v e l y and worked up as d e s c r i b e d above. combination, acetaldehyde was  From the ethanol d i s t i l l a t e s a f t e r  i s o l a t e d as the  2,4-dmitrophenylhydrazone.  - 183 —  1  ,  1  2600 FIGURE of  ,  2800 52  UV  Spectrum  meso — Hydrobenzcin  1  ,  1  3000  3200  of A c e t a l d e h y d e Dinitrate  in  from  Ethanol  the  ,  "X  .  (X)  Photolysis  - 184 -  The sample melted at 164*5-165.5°,,  The NMR  a c i d matched that of an authentic sample r  C, 42.86;  H, 3.60;  N, 24.99.  Pound:  spectrum taken i n t r i f l u o r a c e t i c  (Table I ) . C a l c . f o r C„H .O.N.s 8 8 4 4 r  C, 42.47;  H, 3,93;  N, 24.33$.  A f t e r chromatographic s e p a r a t i o n ( c f . k i n e t i c experiments) of the unreacted n i t r a t e e s t e r the methanol eluates from the three s o l u t i o n s were combined and evaporated t o a v i s c o u s o i l which d i d not resemble benzaldehyde, because i t smelled l i k e burned sugar. phenylhydrazone i s o l a t e d melted a t 238-245°; dehyde 2,4-dmitrophenylhydrazone was 237°.  However, the 2 , 4 - d i n i t r o the reported m.p.  f o r benzal-  An authentic sample melted a t  240-241° and the mixed m e l t i n g p o i n t was found to be 241-243°.  REFERENCES  - 186 -  1.  A. Schonber^. P r e p a r a t i v e Organische Sprmger-Verlag, B e r l i n . 1958.  Fhotochmie.  2.  C. R e i d . E x c i t e d States i n Chemistry and B i o l o g y . Butterworths S c i e n t i f i c P u b l i c a t i o n s , London. 1957.  3.  M. C a l v i n and J . A. Basham. The Photosynthesis of Carbon Compounds. W.A. Benjamin Inc. P u b l i s h e r , New York. 1962.  4.  G. F e r r a r i and R. C u l t r e r a .  Gazz. chim. i t a l . 90, 1712  5.  R. C u l t r e r a and G. F e r r a r i .  Agrochimica j5_, 108  6.  L. P a u l i n g . The Nature of the Chemical Bond. P r e s s . 2nd Edn. 19&,  7.  J . Hmze and H. H. J a f f e .  8.  Y. Tanaka and A. S. J u r s a .  9.  D. C. F r o s t , D. Mak and C.A. McDowell,  p498^.  (1961). Cornell University  J . Am. Chem. Soc. 84, 540 J . Chem. Phys.  (i960).  36 , 2493  (1962). (1962).  Can. J . Chem. 40 , 1064 (1962).  10.  T. Nakayama, M. Y. Kitamura and K. Watanabe. 1180 (1959).  11.  M. Green and J . ¥ . L i n n e t .  12.  K. L. McEwen.  13.  R, Daudel, R. Lefebvre and C. Moser. Quantum Chemistry, Methods and A p p l i c a t i o n s . Interscience P u b l i s h e r 1959, p. 74-75.  14.  H. Gilman and F . Schulze.  15.  R. E . Dessy.  16.  L. H. Long and D. D o l l i m o r e .  17.  R. B. Booth and C. Kraus.  18.  J . C. Lockhart.  19.  A. Chaney and M. L . Wolfrom.  20.  R. E . Banks and R. N. H a s z e l d i n e . Perfluoroalkyl Derivatives i n Adv. Inorg. Chem. and Radiochem. (Edited by H.J. Emelius and A. G. Sharpe ) 3 , 363-364 (1961).  21.  J . A, Young, S. N« Tsoukalas and R. D. Dresdner. 80 , 3604 (1958).  22.  F . E . Ray and G.  ?  Trans. Farad. Soc. 57,1  J , Chem. Phys.  32 , 1813  (1961).  (i960).  J . Am. Chem. Soc.  J . Am. Chem. Soc.  82 , 1580  49 , 2904  J . Am. Chem. Soc. 1197  (1927).  (i960).  J . Chem. Soc. 3902, 3906  J . Chem. Soc.  Szasz.  J . Chem. Phys. 30  74 ,1415  (1953). (1952).  (1962).  J . Org. Chem.  J . Org. Chem.  26 , 2998  (l96l).  J . Am. Chem. Soc.  J$ > 121  (1943).  - 187 -  23.  M. Schmidt and H. Schmidbaur.  Angew. Chem.  71 , 220  24.  J . Honeyman and J . W. W. Morgan.  25.  M. A. Cook. (1958).  26.  C. R. M a r s h a l l .  27.  P. Gray and L. D. Hayward. In ^preparation.  28.  L, P a u l i n g and L . 0. Brockway.  29.  A. D. Booth and F . J . L l e w e l l y n .  30.  W. B. Dixon and E . B. Wilson, J r .  31.  F. Rogowski.  32.  H. E . Weaver, B. M. T o l b e r t and R. C. LaForce. 23 , 1956 (1955).  33.  A. S t r e i t w i e s e r , J r . , Molecular O r b i t a l Theory f o r Organic Chemists. John Wiley & Sons Inc. (1961) p.43.  34.  J . Chedin. J . Phys. Radium (Series 7) Chem. A b s t r . 34 1250 (1940).  35.  A. F. F e r r i s , K. W. McLean, I . G. Marks and W. D. Emmons. J . Am. Chem, Soc. 75 , 4078 (1953).  36.  L. F i s h b e m .  J . Am. Chem. Soc. 7 9 , 2959  (1957).  37.  R. Boschan.  J . Am. Chem. Soc.  8 1 , 3341  (1959).  38.  G. A. Mortimer.  27 . 1876  (1962).  39.  E . D. Hughes, C. K. Ingold and R. B. Pearson. (1958).  40.  S. I s r a e l a s h v i l i .  41.  E . L. B l a c k a l l , E . D. Hughes, C. K. Ingold and R. B. Pearson. J . Chem. Soc. 4366 (1958).  42.  R. Boschan, R. T. Merrow and R. W. vanDolah. 485 (1955).  43.  E . Buncel and A. N. Bourns.  44.  L. D. Hayward. A b s t r a c t of Papers. C.I.C. Organic Symposium, Edmonton, September 6-7 (i960); Chemistry i n Canada 12 , 77 (Oct. I960).  Adv. Carb. Chem.  The Science of High E x p l o s i v e s .  12 , 117  (1957).  Reinhold P u b l . Co.  J . P h a r m a c o l . E x p t l . Therap.  83 , 106  (1948).  The Chemistry of N i t r a t e E s t e r s .  B e r . 75 * 244  J . Am. Chem. Soc. 59 , 13 J . Chem. Soc. 847 J . Chem. Phys.  (1937).  (1947).  35 , 191  (1961).  (1942).  J . Org. Chem.  Nature  (1959).  165_, 686  J . Chem. Phys.  1 0 , 445 (1939).  J . Chem. Soc. 4357  (1950).  Chem. Rev. 55_,  Can. J . Chem. J38, 2457  (i960).  - 188 -  45.  H. R. Wright and W« J , Donaldson. Chem. A b s t r . 4 1 3485 (1947).  U. S. P a t .  2,416,974.  9  46.  A. V. Topchiev. N i t r a t i o n of Hydrocarbons and other Organic Compounds. Pergamon P r e s s , New York. 1959. p.289.  47.  E . Bodker.  48.  H. Moissan and P. Lebeau.  Compt. rend.  140, 1621  (1905).  49.  H. Moissan and P. Lebeau.  Compt. rend.  140,1573  (1905).  50.  G. Hetherington and P. L« Robinson.  51.  G. Hetherington and P. L . Robinson. Recent Aspects of the Inorganic Chemistry of N i t r o g e n . The Chemical S o c i e t y (London). S p e c i a l P u b l i c a t i o n 1 0 , 23 (1957).  52.  C. C. P r i c e and C. A, Sears.  53.  R. J . G i l l e s p i e and D. J . M i l l e n .  54.  G. W. H. Cheeseman.  55.  J . W. Baker and D. M. E a s t y .  J . Chem. Soc. 1193  (1952).  56.  J . ¥ . Baker and D. M. E a s t y .  J . Chem. Soc. 1208  (1952).  57.  M. Anbar, F. Dostrovsky, D. Samuel and A. D. Y o f f e . 3603 (1954).  58.  L. D. Hayward.  59.  G. G. McKeown and L« D. Hayward.  60.  G. H. S e g a l l and C. B. Purves.  61.  L. D. Hayward and C. B. Purves.  62.  M. Jackson and L« D. Hayward.  63.  A. Zane, M.Sc. T h e s i s , U n i v e r s i t y of B r i t i s h Columbia  64.  J . Hme. " P h y s i c a l Organic Chemistry". Chapt. 7. p.168,  65.  J . W. Baker and D. M. E a s t y .  J . Chem. Soc. 1193  66.  J . W. Baker and T, G. Heggs.  J . Chem. Soc. 616  B u l l . s o c . chim. France GO  3 , 726  (1908),  J , Chem. Soc. 3512  (1954).  J . Am. Chem. Soc. 75 , 3276 Quart. Rev. 2 2 7 8 3  J . Chem. Soc. 115  Can. J . Chem. Can. J . Chem. Can. J . Chem.  J . Chem. Soc.  (l95l).  Can. J . Chem.  448  (1948).  (1957).  J , Am. Chem. Soc. 73 , 1974  J . Chem. Soc.  (1953J.  3 3 , 1392 (1955).  30, 860  (1952).  32 , 19  (1954).  38 , 496  (i960). (1958).  McGraw H i l l (1956)  (1952). (1955).  67.  G. W. H. Cheeseman.  (1959).  68.  I..G. Csizmadia, M.Sc* T h e s i s , U n i v e r s i t y of B r i t i s h Columbia  (1959).  - 189 -  69.  E . Buncel and A. N. Bourns.  70.  P. Gray and A. W i l l i a m s . Chem. Rev. 5 9 , 239  -7-J>5  Can. J . Chem.  38, 2457  (i960).  (1959).  M-. A. Cook-;—"The Soicaco of High E x p l o s i v o s " . — R e i n h o l d -Publiohaog Co,—(1958K  72.  J . Powlmg and W. A. W. Smith. (1957).  Combustion  and Flame,  73.  P. Gray and A. D. Y o f f e .  74.  J . Powlmg and W. A. W. Smith.  75.  H. A. Bent and B. Crawford, J r .  76.  F. Shafizadeh, M. L. Wolfrom and P. McWain. 81 1221 (1959).  P r o c . Roy. S c . A200, 114 0  Combustion  308  (1949).  and Flame £ , 157  J . Phys. Chem.  (1958).  63, 941 ^ £ 9 5 9 ) .  J . Am. Chem. Soc.  3  77.  M. L. Wolfrom, A. Chaney and K, S, Ennor. 3469 (1959).  78.  M. L. Wolfrom and G. P. A r s e n a u l t . J . Am. Chem. Soc. 82 , 2819 (1960).  79.  W.Will.  80.  R. Steinberg, C. A. O r l i c k and V. P. Schaaf. 7 7 , 4748 (1955).  81.  J . B. Levy.  82.  L. P h i l l i p s , T h e s i s , U n i v e r s i t y of London, 1949.  83.  L. P h i l l i p s , Nature  84.  A. I . Serbmov.  85.  R. W. P h i l l i p s , C. A. O r l i c k , R. S t e i n b e r g , J . Phys. Chem. 1034 (1955).  86.  M, A. M i l l e t t , R. M. Seborg, L. L. Zoch and F. J . M a s u e l l i . Tappi 4 4 , 636 (1961).  87.  L. F . R. C a f f e r a t a , J . E . S i c r e and H. J . Schumacker, f u r Phys. Chem, (Frankfurt) 2 9 , 188 (1961).  88.  W. E . Skiens and G. H. Ca4y. J . Am. Chem. Soc.  89.  D. H. R, Barton, J . M. Beaton, L. G. G e l l e r and M. M. Pecket. J . Am. Chem. Soc. 82, 2640 (i960).  90.  L. H. P i e t t e and W. C. Landgraf.  Z. Angew. Chem.  14, 774  J . Am. Chem. Soc.  1 6 0 , 753  Zh. f i z . Khim  J . Am. Chem. Soc. 8 1 ,  (1901).  76 , 3790  J . Am. Chem. Soc.  (1954).  (1947). 3 3 , 559  (1959).  J . Chem. Phys.  Z.  80 , 5640  32,  59 «  (1958).  1107  (i960).  - 190 -  91.  A. L. Nussbaum and C. H. Robinson.  92.  H. W. Thomson and C. H. P u r k i s .  93.  S.F.Mason.  94.  J . A. Gray and D. W. G. S t y l e .  95.  H. E. Ungnade and R. A. Smiley.  96.  C. N. R. Rao. U l t r a - V i o l e t and V i s i b l e Spectroscopy. London, ( l 9 6 l ) .  97.  J . ¥ . Sidman.  98.  S. Nagakura.  99.  J . A. Gray and D. W. G. S t y l e .  Quart. Rev. 15,  2t  i  17,  287  5  674  (1936).  Soc. 48, 1137  (1952).  J . Org. Chem. 2 1 , 993  79,  2669  (1956). Butterworths,  (1957).  (i960).  2  Trans F a r a d . Soc.  100.  P. A. Leighton. New York, 1961.  Photochemistry of a i r p o l l u t i o n .  101.  H. Watanabe and Y. Toyoda. Japan Pat. Chem. A b s t r . 55_, 5035 ab (1961).  102.  J . A. H i c k s .  103.  S. Claesson and G. wiSjfermark.  104.  S. Claesson, G. Palm and G. Watermark.  105.  L. D. Hayward, R. A. K i t c h e n and D. J . L i v i n g s t o n e . 434 (1962).  106.  G. C i a m y c i a n and P. S i l b e r .  107.  P. de Mayo and S. T. R e i d .  108.  J * K. Fawcett.  109.  V. M. Csizmadia and L . D. Hayward.  110.  M. Davis and N. Jonathan.  111.  P. Coppens.  112.  0. P. Strausz and H. E« Gunning.  113.  W. Kemula and A. Grabowska. Sciences 8_, 517 ( i 9 6 0 ) .  114.  J . P. Simons.  115.  C. R e i d .  Trans. F a r a d . Soc.  5_2,  3393  1526  49,  52  (1953).  Academic Press,  ('60) A p r i l 9.  (1956).  A r k i v f o r Kemi  17,  355  (l96l).  A r k i v f o r Kemi 1_7, 579 (1961).  B e r . 34, Quart. Rev.  2040  Can. J . Chem. 40,  (1901).  15_, 393  (1961).  U n i v e r s i t y of B r i t i s h Columbia Personal  36,  2523  (1962).  communication.  Trans. Farad. Soc. 54,  J . Chem. Phys.  (1962).  (1961).  Trans. F a r a d .  B.Sc. T h e s i s .  35  Trans. Farad. Soc. 32,  J . Am. Chem. Soc. M o l . Phys.  Tetrahedron  469  (1958).  (1962).  Can. J . Chem.  39»  2  5  4  9  (1961).  B u l l e t i n de 1*Academic Polonaise des.  Quart. Rev.  L3,  3  (1959).  Quart. Rev. 12,  205  (1958).  - 191 -  116.  M. Kasha.  Chem. Rev. 41,  401  (1947).  117.  W. Kemula and A. Grabowska. B u l l e t i n de l'Academie Polonaise des Sciences 6, 747 (1958).  118.  W. Kemula and A. Grabowska. Sciences 9, 525 (i960).  119.  R. G. V. N o r r i s h .  J . Chem. Soc.  50,  774  120.  R. G. W. N o r r i s h .  J . Chem. Soc.  51,  1604  121.  R. G. W. N o r r i s h . (1961 November).  The Adv. of S c i .  122.  H. F o r d . Progress Report No. 20-393. J e t P r o p u l s i o n Laboratory ( C a l i f . Inst, of Techn. Pasadena. C a l i f ) (i960).  123.  J . L. Riebsomer.  124.  P. Gray and A. D. l o f f e .  125.  M. B e r t h e l o t .  126.  W. C. Reynolds and W. H. T a y l o r .  127.  H. A. Mahlman.  128.  B. B. C o l d w e l l and S. R. McLean.  Can. J . Chem.  36,  652  129.  B. B. C o l d w e l l and S. R. McLean.  Can. J . Chem.  37,  1637  130.  H. M. Brown and G. C. P i m e n t a l .  29,  883  131.  T. Kubota and M. Xamakawa. B u l l . Chem. Soc. Japan.  132.  N. Hata.  133.  Table of Interatomic Distances and C o n f i g u r a t i o n i n Molecules and Ions, The Chemical S o c i e t y , (London), S p e c i a l P u b l i c a t i o n No. 11, B u r l i n g t o n House, W.I., (1958).  134.  V. Gold, E . D. Hughes and C. K. Ingold.  135.  H. Burton and P. F . G. P r a i l l .  136.  J . Chedin and S. Feneant.  137.  R. A. Marcus and J . M. F r e s c o .  138.  M. A, P a u l .  139.  A. F i s c h e r , J . Packer, J . Vaughan and G. J . Wright. 369 (1961).  B u l l e t i n de l'Academie Polonaise des  Chem. Rev. 36,  157  127, 83  No.74,  35,  1  0  6  (1955).  9  (1898),  936  101,  34,  1440  (1912).  (1958). (1959). (1958).  35, 555  729  229 , 115  J . Chem. Phys.  J . Am, Chem. S c . 80, 5329  (1962).  (1961).  J . Chem. Soc. 2476  J . Chem. Soc.  Comp. rend.  131  (1961).  J . Chem. Phys.  B u l l . Chem. Soc. Japan.  1  (1945).  J . Chem, Soc.  J . Chem. Phys.  0  (1929).  (BAAS)  Chem. Rev. 55'  Compt. rend.  (1928).  (1950).  (1955). (1949).  2 7 , 564  (1957)  (1958). Proc. Chem. Soc.  - 192 -  140.  R. D. Brown,  J . Chem. Soc.  2224  141.  E . D. Hughes. Kekule Symposium. Butterworths S c i e n t i f i c P u b l i c a t i o n s , London. (1958) p.209.  142.  K. Watanabe.  143.  D. A. Hahan and H. E. Holmes.  144.  I . G-. Csizmadia and L . D. Hayward.  145.  L . Robert.  146.  W. A. Schroeder.  147.  R. K. I l l e r . The C o l l o i d Chemistry of S i l i c a and S i l i c a t e s , C o r n e l l U n i v e r s i t y P r e s s , Ithaca, N. I . (1955) p.238.  148.  R. P. Eischens and W, A. P l i s k i n . Advances i n C a t a l y s i s , Academic Press, New York. 10 , 1-56 (1958).  149.  R. S. McDonald.  150.  M. Folman and D. J . C. Yates. 246 A . 32 (1958).  Proc. Roy. Soc. (London).  151.  M. Folman and D. J . C. Y a t e s .  J . Phys. Chem.  152.  M. R. B a s i l a .  35» 1151  153.  A. H. Sporer and K. N. Trueblood.  154.  E . Lederer and M. Lederer. Chromatqgraphy. 2nd ed. E l s e v i e r P u b l i s h i n g Co. Amsterdam. " (1957).  155.  I . G. Csizmadia, D. J . Livingstone and L. D. Hayward, unpublished r e s u l t s .  156.  G. R. Duncan.  157.  G. R. R i t t e r and G. M. Meyer.  158.  W. E . E l i a s and L . D. Hayward.  159.  J . Noguchi.  160.  D. J . L i v i n g s t o n e .  161.  P. R. Hammond.  162.  B. P. D a i l e y and J . N. Schoolery. 7 7 , 3977 (1955).  163.  J . A. Pople, W. G. Schneider and H. J . B e r n s t e i n . High - R e s o l u t i o n Nuclear Magnetic Resonance. McGraw H i l l Book Co., New York, (1959).  J . Chem. Phys.  Compt. rend.  (1959).  2 6 , 542  (1957).  Ind. Eng. Chem. 13., 822  234,  Tetrahedron i n p r e s s .  2066  (1952).  J . Am. Chem. Soc. 73 , 1122  J * Phys. Chem.  J . Chem. Phys.  J . Chromat.  62 , 1168  (1951).  (1958).  63 , 183  (1959).  (1961).  J . Chromat.  .8, 37  2., 499  (1959).  (1962).  Nature Tappi.  S c i . Papers Osaka Univ. Personal  (1921).  193,941  (19,62).  4 1 , 246  (1958).  No. 221  (1951).  communication.  J . Chem. Soc. 1370  (1962).  J . Am. Chem. Soc.  - 193 -  164.  I. G. Gsizmadia and L . D. Hayward. Abstract of Papers C.I.C. 45th Conference, Edmonton* May 27-30, (1962). Chemistry i n Canada 14 (No. 4) 29 (1962).  165.  V. M, Csizmadia and L . D. Hayward.  166.  R. D. Guthrie and H. Spedding,  167.  D. N. W. Anderson, G. 0. A s p i n a l l , J . L. Duncan and J . P. Smith, Spectrochim. A c t a . 17, 1001 (1961).  168.  F. P r i s t e r a , M. H a l i k , A. C a s t e l l i and W, F r e d e r i c k s . A n a l . Chem. 32 ,495 ( i 9 6 0 ) .  169.  R. A. E . C a r n n g t o n ,  170.  H. von Halban and J . Eisenbrand.  171.  M. I t o and N. Hata.  172.  M. I t o , K. Inuzuka and S. Imanshi.  173.  M. I t o , K. Inuzuka and S. Imanishi.  174.  H. E . Ungnade, E . D. Longhran and L . W. K i s s i n g e r . J . Phys. Chem. 64,1410 (i960).  175.  C. C. P r i c e and R. J . Convery.  J . Am. Chem. Soc. 79 , 2941  176.  P.Gray.  (1962).  177.  P. Kabasakalian, E . R. Townley and M. D. Yudis. J . Am. Chem, Soc. '84, 2716 (1962).  178.  R. M. Hochstrasser and G. B. P o r t e r .  179.  A-; 'Teranin"and ¥1 E r r a a l d v ^ n l ^ . i f t a k l . Soc. 52 ,1042  180.  G. P o r t e r and F . W i l k i n s o n .  Trans. Farad. Soc. 57 , 1686  181.  W. M. Moore and M. Ketchum.  J . Am, Chem. Soc. 84 , 1368  182.  J . B. Farmer, C. L . Gardner and C. A. McDowell. 34 , 1058 (1961).  183.  W. West and W. E . M i l l e r .  184.  0. Schnepp and M. Levy.  185.  A. W e l l e r . Fast Reactions of E x c i t e d Molecules. _In Progress i n Reaction K i n e t i c s (Edited by G. P o r t e r ) Pergamon P r e s s . New York, 1961., V o l . 1. p.187.  186.  W. Bartok, D. J . Lucchesi and N. S. S n i d e r . 1842 (1962),  To be p u b l i s h e d .  J . Chem. Soc. 953  Spectrochim. Acta  16, 1279  Z. Phys. Chem.  B u l l . Chem. Soc. Japan  Tetrahedron  18,875  (i960).  (i960). 132, 401  2 8 , 260  J . Chem. Phys.  (1928).  (1955).  31 , 1694  (1959).  J . Am. Chem, Soc. 82 , 1317  Quart. Rev.  J . Chem. Phys.  (i960).  (1957).  14 , 146  (i960),  (1956). (l96l). (1962).  J . Chem. Phys.  8_, 849  J . Am. Chem. Soc. 84 , 172  (1940). (1962).  J . Am. Chem. Soc. 84 ,  - 194 -  187.  G-. P o r t e r . Mechanism of P h o t o s e n s i t i z a t i o n i n S o l u t i o n . In Photochemistry i n L i q u i d and S o l i d State (Edited by L.S. H e i d t , R. S. L i v i n g s t o n e , E . Rabinowith, and P. Daniels,") John Wiley, New York 1960. p.35.  188.  J . W. Eastman, G!.->Eigelsmaand M.Cftlvm. J . Am. Chem. Soc. 84 ,339  189.  J . Cunningham.  190.  T. J . Stone and W. A. Waters.  191.  S. J . Weissman, J . Chem. Phys.  192.  C. A. Hutchison, J r . , and B. W. Mangum.  193.  S. Nagakura.  194.  C. L. Gardner.  195  L. D, Hayward and D«, J . L i v i n g s t o n e .  £  J . Phys. Chem.  Molec. Phys. Personal  66 ,779  (1962).  P r o c . Chem. Soc. 253 2 9 , 1189  2,152  (1962).  (1962).  (1958). J . Chem. Phys. 2 9 , 952  (1958).  (i960).  communication. Unpublished r e s u l t s .  196.  A. I . V o g e l . P r a c t i c a l Organic Chemistry. 3rd. Edn. 1959.  197.  S i r . I . H e i l b r o n and H. M. Bunbury. D i c t i o n a r y of Organic Compounds. Eyre and Spottiswoode, London, 1946.  198.  W. H. Hartung.  199.  L. W. Trevoy and W. G. Brown.  200.  L. F. F i e s e r . Experiments i n Organic Chemistry. 3rd Edn. 1957.  201.  H. Merween and R. Schmidt.  Aaa. 444, 234  202.  G. F a u s t .  6  203.  D. J . Cram, N. L . A l l m g e r and H. S t e i n b e r g . J . Am. Chem. Soc. 76 ,6132 (1954).  204.  L. Erdey. I n t r o d u c t i o n t o CheiniaaLAnlal^sa's,r;VM ..(2.. Volumetric A n a l y s i s . 2nd E d , Acidemia P u b l i s h e r , Budapest,  J . Am. Chem. Soc.  J . P r a c t . Chem.  Angew. Chem.  Longmans London.  5 0 , 3372  (1928).  J . Am. Chem. Soc. 7 1 , 1676  ( N o . l ) , 14  205.  T. Arnd.  30 1 6 9  206.  G. Grime and W. M. Jones,  207.  R. von Walther and A. W e t z l i c h . 61 , 169 (1900).  208.  V. M. Csizmadia, M.Sc. T h e s i s .  209.  L. B. Rockland and M. S. Duran.  s  (1949).  D. C. Heath Co.,  (1925). (1958).  (l95l).  (1917)  P h i l . Mag.  7_> 1113  (1929).  J . P r a c t . Chem.  (2)  U n i v e r s i t y of B r i t i s h Columbia Science  109,  539  (1949).  (1961).  - 195 -  210.  J . H. Dhout and C. de Roy. A n a l y s t  211.  M. Jackson and L. D. Hayward.  212.  R. U. Lemaeux and H. F . Bauer.  213.  R. H. Calligham, M. F . Tarker, J r . , and M. H . i l T i l t . J . Org. Chem. 2 6 , 1379 (1961).  214.  F . J . A d r i a n . J . C h e m . P h y s . 3 6 , 1692 (1962)  Z\S  L.C ^aML^orJL  a*,ct«GolWt  ) 4*  8 6 74  (1961).  5  J . Chromat.  5_ 166 5  A n a l . Chem. 27  6U,  3  920  (l96l). (1959).  Sac V 7 , "*5% (l°>25)  4  

Cite

Citation Scheme:

        

Citations by CSL (citeproc-js)

Usage Statistics

Share

Embed

Customize your widget with the following options, then copy and paste the code below into the HTML of your page to embed this item in your website.
                        
                            <div id="ubcOpenCollectionsWidgetDisplay">
                            <script id="ubcOpenCollectionsWidget"
                            src="{[{embed.src}]}"
                            data-item="{[{embed.item}]}"
                            data-collection="{[{embed.collection}]}"
                            data-metadata="{[{embed.showMetadata}]}"
                            data-width="{[{embed.width}]}"
                            async >
                            </script>
                            </div>
                        
                    
IIIF logo Our image viewer uses the IIIF 2.0 standard. To load this item in other compatible viewers, use this url:
http://iiif.library.ubc.ca/presentation/dsp.831.1-0062250/manifest

Comment

Related Items