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A proposed study of the cyclopentadienyl anion using carbon-14 as a tracer Tkachuk, Russell 1956

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PROPOSED STUDY OF....:. THE GYGLOPEHTADIEEYL ANION USING CAKBON-14 AS A TRACER, by RUSSELL TKACHUK A THESIS SUBMITTED IN PARTIAL FIILFLLMEM OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE i n the Department of CHEMISTRY We accept t h i s t h e s i s as conforming to the standards r e q u i r e d from candidates f o r the degree of MASTER OF SCIENCE Members of the department of Chemistry THE UNIVERSITY OF BRITISH COLUMBIA A p r i l , 1956 ABSTRACT I t i s thought t h a t some i n f o r m a t i o n about the bond s t r u c t u r e i n the c y c l o p e n t a d i e n y l anion can be provided by s y n t h e s i z i n g cyclopentadiene-5-C^, making the c y c l o -p e ntadienyl anion (as the potassium s a l t ) , and degrading the cyclopentadiene regenerated from t h i s anion f o r the determination of the d i s t r i b u t i o n of carbon-14: DEGRADATION A method f o r the s y n t h e s i s of cyclopentadiene, s t a r t i n g from formaldehyde, has been shown. The potassium c y c l o -p e n t a d i e n y l s a l t was then made. The cyclopentadiene regenerated from t h i s s a l t was completely degraded. Repet-i t i o n of t h i s work, u s i n g formaldehyde-C^ would give the des i r e d cyclopentadiene-5-C^, e t c . Using carbon-14, the precursor t o cyclopen t a d i e n e - 5 - G ^ was made, but the sy n t h e s i s of cyc l o p e n t a d i e n e - 5 - C ^ could not be c a r r i e d out i n the a v a i l a b l e time. ACKN0TO5DGMEHT The author wishes to express h i s a p p r e c i a t i o n of the encouragement, advice, and a s s i s t a n c e given by Dr. C. G. Lee d u r i n g the course of t h i s research. TABLE OF CONTENTS General I n t r o d u c t i o n - - - - - - - - - - - 1 H i s t o r i c a l I n t r o d u c t i o n A. General . 2 B. The Cyclopentadienyl Anion 7 D i s c u s s i o n A. Synthesis of Cyclopentadiene - - - - 10 B. Sy n t h e t i c and Degradative Procedures 14 Experimental A. Solvents and Reagents - - - - - - - 19 B. Sy n t h e t i c and Degradative Procedures 21 B i b l i o g r a p h y - - - - - - - - - - - - - - - 38 GENERAL INTRODUCTION The object of t h i s work i s a proposed study of the bond-structure of the c y c l o p e n t a d i e n y l anion. The present theory of "aromatic c h a r a c t e r " a s c r i b e s the s t a b i l i t y of aro-matic compounds, of which the c y c l o p e n t a d i e n y l anion i s a member, to those unsaturated conjugated c y c l i c systems having s i x r esonating T T - e l e c t r o n s . In the c y c l o p e n t a d i e n y l anion, the s e . c o n d i t i o n s are f u l f i l l e d by u t i l i z i n g the two e l e c t r o n s which form e r l y h e l d a carbon-hydrogen bond together i n the methylene group of cyclopentadiene: He—CH II II + K ° . HC OH 8 H HC-—CM // w H C _ _ C H /• — 1} H However, experimental v e r i f i c a t i o n of these p r e d i c a t i o n s i s incomplete. I t i s thought that t h i s v e r i f i c a t i o n , or other-wise, can be obtained i n the case of the c y c l o p e n t a d i e n y l anion, by the use of carbon-14- as a t r a c e r . This can be done by sy n t h e s i z i n g cyclopentadiene-5-C^- 4, making the potassium anion, and then regenerating cyclopentadiene from t h i s l a t t e r s a l t * DEGRADATION 2. I f the anion i s aromatic according to our present d e f i n i t i o n of a r o m a t i c i t y , then the carbon-14 i n the regenerated c y c l o -pentadiene w i l l be d i s t r i b u t e d e q u a l l y on every carbon atom. I f the negative charge remains on the former methylene group, the o r i g i n a l cyclopentadiene-5 - c l 4 " w i l l be regenerated, e t c . The aim i n the present work was to f i n d a s u i t a b l e h y p o t h e t i c a l synthesis f o r cyclopentadiene-5-C 1 4", and a method f o r the r e g e n e r a t i o n of cyclopentadiene from i t s potassium s a l t . This was done. To f a m i l i a r i z e o n eself w i t h the r e a c t i o n procedures and t o l e a r n the o v e r - a l l y i e l d , a complete s y n t h e s i s , formation of the potassium s a l t , r e g e n e r a t i o n , and a complete degradation of cyclopentadiene were e f f e c t e d . Time p e r m i t t i n g , the above work was t o be repeated as f a r as p o s s i b l e , using carbon-14. Cyclopentane-l,2-diol-5-C 1 4- ( c i s - t r a n s ) was synthesized, but the dehydration of i t to cyclopentadiene could not be repeated. HISTORICAL INTRODUCTION (A) GENERAL Aromatic compounds were so c l a s s i f i e d o r i g i n a l l y because of t h e i r odor. Today a r o m a t i c i t y or aromatic character i n f e r s a much d i f f e r e n t meaning. Although there i s much d i s -agreement on the d e f i n i t i o n of a r o m a t i c i t y , very b r i e f l y i t may be a s s o c i a t e d w i t h c y c l i c compounds possessing the f o l l o w i n g p r o p e r t i e s : (1) A very s t a b l e nucleus of carbon atoms (2) A p a r t i c u l a r l y r e s i s t a n t type of u n s a t u r a t i o n towards the formation of a d d i t i o n a l products (3) A tendency to undergo s u b s t i t u t i o n r e a c t i o n s (4) A c i d i c e n o l i c d e r i v a t i v e s w i t h l i t t l e tendency to form the "keto form" (5) A tendency to form quinone and diazonium s a l t s (6) Halide d e r i v a t i v e s which are very i n e r t (7) A pronounced tendency towards t h e i r formation. Benzene and i t s d e r i v a t i v e s of course provide the c l a s s i c a l example of i l l u s t r a t i n g these p r o p e r t i e s . Chemists e l u c i d a t i n g the p r o p e r t i e s and s t r u c t u r e s of these aromatic compounds have come up w i t h many t h e o r i e s . One school of thought, due t o Armstrong, von Baeyer and Bamberger, suggested t h a t aromatic character was due to the symmetrical arrangement of conjugated l i n k a g e s i n these c y c l i c compounds. Independently, Armstrong (3) i n 1887 and von Baeyer (4) i n 1888 provided f o r benzene a symbol based on the 2 4 - a f f i n i t i e s of the s i x carbon atoms. Of these 2 4 - a f f i n i t i e s , 12 are engaged i n the formation of the six- c a r b o n r i n g and s i x r e t a i n i n g the s i x hydrogen atoms, w h i l e the remaining s i x r e a c t upon each o t h e r — " a c t i n g towards a centre as i t were"—so that the "A f f i n i t y " m a y be s a i d to be uniformly and symmetrically d i s t r i b u t e d (3): H M C C / \ / \ 4 Bamberger ( 6 ) , i n 1891-1893, suggested that the s i x valences unnecessary f o r the formation of benzene " s a t u r a t e d each other". Rings not having s i x such valences could not a t t a i n the same s t a b i l i t y . Bamberger extended h i s h e x a c e n t r i c argument to unsaturated h e t e r o c y c l i c s by u t i l i z i n g the s a l t forming valences of the hetero-atoms: 0 5 P 5 Q P y r i d i n e P y r r o l e Thiophene Pyrazole(Imidazole) Furan T h i e l e (53) i n 1899, considered t h a t each carbon atom of a double-bond to possess a p a r t i a l valence, and t h a t i n a diene these p a r t i a l valences n e u t r a l i z e each other w i t h the r e -s u l t i n g accumulation of r e s i d u a l energy at the ends of the conjugated system (t© e x p l a i n 1 , 4-additions): I — " I • I Applying t h i s argument to 4ke Kekules c y c l o h e x a t r i e n e formula f o r benzene w i t h i t s c l o s e d conjugated system, three i n a c t i v e double bonds a l t e r n a t i n g w i t h the o r i g i n a l / , d e a c t i v a t e d double bonds are formed, r e s u l t i n g i n s i x n e a r l y e q u i v a l e n t i n e r t l i n k a g e s : 5 I n the nineteenth century, the valence bond was represented by a l i n e drawn between the symbols of two chemical elements, the nature of the bond being unknown. F o l l o w i n g the d i s c o v e r y of the e l e c t r o n i n 1897• e l e c t r o n s i n s t e a d of the former l i n e s soon appeared as the l i n k between atoms i n chemical compounds. However, i t was not u n t i l 1 9 1 6 , when G. N. Lewis (40) formulated the b a s i s of the modern e l e c t r o n i c theory of valence. And so e l e c t r o n i c formulae f o r benzene soon appeared i n the l i t e r a t u r e : H H--c * 'C-.H H > c , „ . - . C - H C • M The f i r s t a l t e r n a t i v e f o r m u l a t i o n f o r benzene, where a l l the nuclear carbon atoms are connected by three e l e c t r o n s , was suggested by Kauffmann(37)» and drawn by Kermac and Robinson (39)« H . c . ri-c '% c*u ... ••• * C ' H L a t e r , Armit and Robinson ( 2 ) suggested t h a t the "aromatic s e x t e t " i n the benzoid group i n f e r s marked s t a b i l i t y and p o s t u l a t e d t h a t groups of two or f o u r e l e c t r o n s a l s o occur, f o r example, i n a c i d s and cyclopentadiene. Gross and Ingold ( 2 8 ) extended Bamberger's theory by a s s i g n i n g e l e c t r o n i c s t r u c t u r e s to the aromatic h e t e r o - c y c l i c compounds: « « H P y r r o l e - (a) P y r r o l e - ( b ) The second formula ( b ) , again gives r i s e t o the aromatic s e x t e t . since Huckel(39) i n 1931 invented the quantum mechanical foun-d a t i o n i n which he a s c r i b e s that aromatic character w i t h i t s r e l a t i v e s t a b i l i t y , o r i g i n a t e s from those conjugated unsaturated c y c l e s c o n t a i n i n g s i x i r - e l e c t r o n s . weweby W i l l s t a t t e r on the non-existent cyclobutadiene (63) and cyclo—octatetraene(62,69)? which t h e o r e t i c a l l y are non-aromatic molecules. Cyclobutadiene s t i l l has not been synthesized and would, i n any case, have a l a r g e obscuring angular s t r a i n . C y clo-octatetraene, although synthesized, has a non-planer s t r u c t u r e and so is"Impertinent to the theory(38). T h e o r e t i c a l predictions.^ concerning the f i v e and s even-member ed r i n g s are d e f i n i t e (26,34,59)•(CH)5 should be more s t a b l e than (CH)y, and (CH)£ should be more s t a b l e than (CH)^i The p o s i t i v e i o n (CH)"£ has never been prepared; but from the f a i l u r e of cyclopenta-dienone to e x i s t as con t r a s t e d w i t h the s t a b i l i t y and b a s i c i t y of cycloheptatrienone, i t can be i n f e r r e d t h a t the (CH) + i o n i s much more s t a b l e than the (CH)£ i o n (15.20). The aromatic sextet theory has r e c e i v e d much a t t e n t i o n The f i r s t attempts to t e s t t h i s aromatic s e x t e t theory I n 1 9 5 4 - , Doering and Kn©x synethesized the c y c l o -h e p t a t r i e n y l i u m (tropylium) i o n (21). From i t s p r o p e r t i e s i t appears t h a t resonance s t a b i l i z a t i o n i n the c y c l i c i o n i s l a r g e enough to overcome the normal tendency ©f the carbon-bromine bond t© be co v a l e n t . Thus we have another new aromatic system i n which l a r g e resonance energy o r i g i n a t e s from the c y c l i c nature ©f the system. In summary the present "aromatic s e x t e t " theory p r e d i c t s that the c y c l e p e n t a d i e n y l i o n , benzene and the c y c l o h e p t a t r i e n y l i u m i o n c o n s t i t u t e a t r i a d possessing aromatic resonance energy and hence remarkable s t a b i l i t y . (B) THE CYCLOPENTADIENYL ANION The resonance energy ©f cyclopentadiene, c a l c u l a t e d from the heat ©f hydrogenation, i s only about 3 kcal/mole (5). But cyclopentadiene possesses an a c t i v e methylene group, and has an e x c e p t i o n a l l y h i g h a c i d i t y f o r a hydrocarbon, as 8. potassium t-butoxide (pK^ 19) converts cyclopentadiene quantitatively into i t s potassium salt(49). This shows that the negatively charged ion ion had six *7T -electrons distributed over five equivalent CH groups, thus constituting a stable aromatic system similar to benzene. The resonance energy of the Ion has been calculated to be about 42 kcal./mole, and apparently i s i n harmony with the observed stability (48). The tendency of the cyclo-pentadiene system to accept an electron and thus achieve aromatic st a b i l i t y i s also shown by the fulvenes. Dimethylfulven (R-RlnMe) has a dipole moment of 1.44D, the ring being negative and the carbon atom-6 positive(60). This indicates the electron attracting nature of the ring which tends to acquire a stable sextet of electrons. The recently i s a very stable molecule. It i s suggested that the molecule i s a resonance hybrid of the two following structures: Is very stable, although very reactive chemically. The reason given by Goss and Ingold (28) i n 1928, was that this prepared diazocyclopentadiene (19) 9. 0 f u -l l N + \\\ N N -The f©rm i n which the r i n g accommodates the negative charge The aromatic character of the cyclopentadienium r i n g i s best i l l u s t r a t e d by dicycl©pentadienyl ir©n (5)* This compound i s i n s o l u b l e i n , and does not r e a c t w i t h water, sodium hydroxide, ©r cone, h y d r o c h l o r i c a c i d . I t i s net de-composed at 470®. The exact nature of the Fe-C bonds i s not known. Regarding the c y c l o p e n t a d i e n y l r i n g s , i n f r a r e d spectrum i n d i c a t e s only one type ©f C-H bond, and X-ray evidence i n d i c a t e s t h a t the five-membered r i n g s are plan a r , and symmetrical, the C-C d i s t a n c e s being about 1*4 A. D i c y c l o p e n t a d i e n y l i r o n does not r e a c t w i t h maleic anhydride, cannot be c a t a l y t i c a l l y hydrogenated, and undergoes the F r i e d e l - C r a f t s r e a c t i o n . Because of these t y p i c a l l y aromatic c h a r a c t e r i s t i c s , the compound has been named f e r r o c e n e . pr©bably c o n t r i b u t e s most t© the h y b r i d . 10. The only experimental work on the s t r u c t u r e of the c y c l o p e n t a d i e n y l anion seems to be t h a t by A l d e r and Holz-r i c h t e r ( 1 ) , who t r e a t e d the potassium s a l t of cyclopentadiene w i t h benzyl c h l o r i d e and obtained both b e n z y l - and d i b e n z y l -cyclopentadienes and t h e i r dimers. From these products only the 1-and 2-benzyl cyclopentadienes were found. Str a n g e l y , the !ir benzyl d e r i v a t i v e was not formed. This work i s l i m i t e d i n t h a t one does not know whether or not the de-p o l y m e r i z a t i o n ©f dicyclopentadiene d e r i v a t i v e s i n v o l v e s tautomeric changes. Besides the f a c t that the 5-benzyl d e r i -v a t i v e d i d not form, the authors could not add any i n f o r m a t i o n t o the s t r u c t u r e of the c y c l o p e n t a d i e n y l anion. DISCUSSION (A) SYNTHESIS OF CYCLOPENTADIENE The immediate precursor t o cyclopentadiene, l a b e l l e d i n the methylene group w i t h carbon-14 was chosen to be ( c i s - t r a n s ) c y c l o p e n t a n e - l - d i o l - 4 - C ^ s i n c e i t was shown i n the present work that cyclopentadiene could 1 1 . be prepared from t r a n s - c y c l o p e n t a n e - l , 2 - d i o l i n a y i e l d of 2 0 $ : CC -«-a Whether the dehydration does proceed as shown above can only be determined by an a c t u a l dehydration.attempt of ( c i s - t r a n s ) * c y c l o p e n t a n e - l , 2 - ^ i o l - 4 - C 1 4 f o l l o w e d by degradation of the cyclopentadiene obtained to a s c e r t a i n the l o c a t i o n of C 1 4 i n the r i n g . I f the dehydration, as shown i n the preceding paragraph, was not s u c c e s s f u l , we s t i l l have two other p o s s i -b i l i t i e s of o b t a i n i n g cyclopentadiene from ( c i s - t r a n s ) c y c l o -p entane-l , 2-diol-4-C 1 4-, or from i t s precursor, 1 , 2-cyclopenta-dione-4-C 3- 4 -. One p o s s i b i l i t y would be a dehydrohalogenation of l ^ - d i b r o m o c y c l o p e n t a n e ^ - c l 4 " according to the f o l l o w i n g scheme: <z - cc - cc o The d i a c e t a t e of c y c l o p e n t a n e - l , 2 d i o l has been prepared (41), and the two remaining steps are s i m i l a r to the s u c c e s s f u l p r e p a r a t i o n of 1 , 3-cyclohexadiene ( 6 5 ) . Furthermore, a s i m i l a r p r e p a r a t i o n has been s u c c e s s f u l i n the p r e p a r a t i o n of c y c l o h e p t a t r i e n e by W i l l s t a t t e r ( 6 l ) . The second p o s s i b i l i t y would be the p r e p a r a t i o n of the dioxime and then the diamine from l , 2 - c y c l o p e n t a d i o n e - 4 which has been r e a l i z e d by Jaeger and Blumendal ( 3 5 ) : 12. =N-OH =N-OH From the diamine, a Hoffmann degradation could be attempted as i n the attempted s y n t h e s i s of cyclobutadiene by Buchman and h i s c o l l a b o r a t o r s (10) or the famous s y n t h e s i s of c y e l o -octatetraene by W i l l s t a t t e r and co-workers (62,64), and more r e c e n t l y by Cope and Overberger (12). seem t o be only three reported r e a c t i o n s which l e a d t o cyclopentadiene. Only one of these methods would be u s e f u l i n t h i s present work, namely, the h y d r o l y s i s of the di - p - t o l u e n e -sulphonate of cyclopentane-l,2-di©l according t o Owen and Smith(44). Besides the cleavage of dic y c l o p e n t a d i e n e , there The y i e l d of cyclopentadiene was not recorded by Owen and Smith. However, i n two attempts t o repeat the work of these authors, no cyclopentadiene could be detected. 13. T h l e l e i n 1901 obtained cyclopentadiene by the r e d u c t i o n of 2,4-dibromo cyclopentene w i t h z i n c dust i n g l a c i a l a c e t i c a c i d (55). T h i e l e d i d not mention the y i e l d , but from h i s d e s c r i p t i o n of the r e a c t i o n , the y i e l d of cyclopentadiene seemed con-s i d e r a b l e . However 2,4-dibromo-cyclopentene i s made from cyclopentadiene, and to synthesize 2,4-dibromo-l-cyclo-pentene-3 seems a very formidable, i f not i m p o s s i b l e , t a s k . F i n a l l y , Braun and Kuhn have reported t h a t , during the p r e p a r a t i o n of o-cyclopentenylphenol, by condensing sodium phenolate and 2 - c y c l o p e n t e n y l , ( 8 ) , an a l k a l i - i n s o l u b l e p o r t i o n of the product was obtained. This l a t t e r o i l , w i t h a b o i l i n g p o i n t of 110-200° at 12 mm., evolved a d i s t i n c t odor of cyclopentadiene. I t would seem t h a t t h i s r e a c t i o n i s not very s u i t a b l e f o r the p r e p a r a t i o n of c y c l o -pentadiene l a b e l l e d i n the 5- p o s i t i o n . (B) SYNTHETIC AND DEGRADATIVE PROCEDURES 14 The p r e l i m i n a r y s y n t h e t i c procedures l i s t e d below were donewithAview t £ p e r f e c t i n g a route f o r the formation of 14 cyclopentadiene - 5-C : C r t l = ° c«<coo£t), tooar coot* C 0 C H C 0 0 £ + The s y n t h e s i s of cyclopentadiene s t a r t e d from formaldehyde, as e v e n t u a l l y the carbon-14 could then be introduced i n the form of formaldehyde-Thus t e t r a e t h y l propane-1,1,3,3*tetracarboxylate(I) was prepared from the condensation of formaldehyde and d i e t h y l malonate and hydrolyzed to g l u t a r i c a c i d ( I I ) . This g l u t a r i c a c i d was then e s t e r i f i e d to d i e t h y l g l u t a r g t e ( I I I ) . A Dieckmann condensation of the l a t t e r w i t h d i e t h y l o x a l a t e gave 3,5-dicarboethoxycyclopentadione-l,2(IV), which on h y d r o l y s i s a f f o r d e d cyclopentadione-l,2(V). Hydrogenation of (V) over platinum oxide, gave apparently an isomeric mixture of ( c i s - t r a n s ) c y c l o p e n t a n e - l , 2 - d i o l s C V T ) . As t h i s l a t t e r product could not be c h a r a c t e r i z e d by o r d i n a r y means, aut h e n t i c t r a n s - c y c l o -pentane-l,2-diol(XXIII) was synthesized, s t a r t i n g from a d i p i c a c i d as i n the f o l l o w i n g sequence: oH H ci ci a cr xtx *x xxi xxn xxti! 15. Cyclopentanone(XX), prepared by heating a d i p i c acid(XIX) w i t h barium hydroxide, was converted to cyclopentanol(XXI) w i t h l i t h i u m aluminum hydride. Dehydration of the l a t t e r a l c o h o l w i t h 85$ ortho-phosphoric a c i d gave cyclopentene(XXII), which i n t u r n was t r a n s - e s t e r i f i e d w i t h performic a c i d and hydrolyzed to give t r a n s - c y c l o p e n t a n e - l , 2 - d i o l ( X X I I I ) . The o v e r - a l l y i e l d •from a d i p i c a c i d was 19.5$. A f t e r the t r a n s - c y c l o p e n t a n e - l , 2 - d i o l was c h a r a c t e r i z e d , an i n f r a red spectrum was taken of i t , and a l s o of the c y c l o -p e n t a n e - l , 2 - d i o l obtained by hydrogenation of cy c l o p e n t a d i o n e - 1 , 2(V). The i n f r a r e d a b s o r p t i o n curves obtained f o r these two a l c o h o l s , as 3% s o l u t i o n s i n chloroform, were superimposable except f o r one e x t r a s l i g h t peak i n the " f i n g e r - p r i n t " r e g i o n f o r the d i o l ( V I ) from the hydrogenation of V. ( F i g . 1, p. 37) Cyclopentadiene(VTI), i n a y i e l d of 20$, was prepared by passing t r a n s - c y c l o p e n t a n e - l , 2 - d i o l over alumina p e l l e t s at 400 ° i The cyclopentadiene produced, besides i t s very c h a r a c t e r i s t i c odor, was c h a r a c t e r i z e d as the maleic anhydride adduct. The p r e p a r a t i o n of cyclopentadiene by t h i s method i s not l i s t e d i n the l i t e r a t u r e . Potassium c y c l o p e n t a d i e n i d e ( I Q I I ) was made by r e a c t i n g cyclopentadiene w i t h m e t a l l i c potassium i n benzene and ether. 16 By using t h i s mixture of s o l v e n t s i n s t e a d of benzene alone, a product i s obtained which i s more f i n e l y d i v i d e d and not as apt t o c o n t a i n very small pieces of unreacted potassium. I f t h i s potassium-cyclopentadiene s a l t does c o n t a i n m e t a l l i c potassium, then the next r e a c t i o n on t h i s s a l t would be very v i g o r o u s , and u s u a l l y would end i n a f i r e . Regeneration of c y c l o p e n t a d i e n e ( I X ) , i n a y i e l d of 43$, was a f f o r d e d by a d d i t i o n of c o l d cone, h y d r o c h l o r i c a c i d : In f u t u r e work, probably higher y i e l d s of cyclopentadiene could be obtained by d i s s o l v i n g the potassium s a l t i n tetrahydro.-->• fiMfy and then adding the t h e o r e t i c a l amount of hydrogen c h l o r i d e gas. T h i e l e (5^) mentioned t h a t cyclopentadiene i s regenerated from potassium s a l t by the a d d i t i o n of water. R e p e t i t i o n of T h i e l e ' s work r e s u l t e d i n a r e s i n formation together w i t h a poor y i e l d of cyclopentadiene. I n t h i s r e a c t i o n j H ) V <w—* (Tj + K 0 H the r e a c t i n g mixture becomes b a s i c as the r e a c t i o n proceeds. Thus, probably, the cyclopentadiene formed i s r a p i d l y p o l y -merized, as a c i d s and bases c a t a l y z e such p o l y m e r i z a t i o n . 1 7 . By adapting former degradations of c i s - c y c l o p e n t a n e - 1 , 2-diamine ( 4 5 ) and s u c c i n i c acid ( 7 ) > the scheme f o r the l o c a t i o n of the carbon - C l 4 i n the cyclopentadiene samples i s as f o l l o w s : !£. . Z xl *3_ xm xTy COOH coorle COHHNHZ cO/V* **• I*. -> i«t CM, ' C H a-**coo* ^ ^ S - C o CM7 ^ c H t ct f i ^ cHi ' cH,-NHcoo6t CH,.NH1 COOH coor t ^ CO/Vff-Jtff/i co/v\t ^ XV XVI xv^l XVIII XIX XX The d i - e t h y l e s t e r of 2 , 3 - d i a z a b i c y c l e ( 2 . 2 . 1 ) - ! ? - h e p t e h e - 2 , 3 - d i e a r b o x y l i c acid(X) was obtained by a D i e l s - A l d e r r e a c t i o n between cyclopentadiene and e t h y l a z o d i c a r b o x y l a t e . Hydrogenation of the D i e l s - A l d e r adduct gave the d i e t h y l e s t e r of 2 , 3 - d i a z a b i c y c l e ( 2 . 2 . 1 ) h e p t a n e - 2 , 3 - d i c a r b o x y l i c a c i d ( X I ) , which, on h y d r o l y s i s w i t h methanolic potassium hydroxide, gave 2 , 3 - d i a z a b i c y c l e ( 2 . 2 . 1 ) heptane ( X I I ) , i s o l a t e d as the cuprous c h l o r i d e complex. Reduction of X I I w i t h t i n and h y d r o c h l o r i c a c i d gave c i s - c y c l o p e n t a n e - 1 , 3 - d i a m i n e ( X I I I ) , which was o x i d i z e d w i t h n e u t r a l potassium permanganate to s u c c i n i c a c i d ( X I V ) . Using the C u r t i u s degradation method('3,l^), the s u c c i n i c acid(XIV) was degraded. I along the sequence of the dimethyl ester(XV) — dihydrazide(XVI) — dia z i d e ( X X V I I ) ~ d i u r e t h a n ( X V I I I ) , and f i n a l l y t o ethylenediamine(XIX) and carbon d i o x i d e ( X X ) . The o v e r - a l l y i e l d of ethylenediamine from cyclopentadiene was 0,4$ 18. The l o c a t i o n of the carbon-14 i n the cyclopentadiene would, h y p o t h e t i c a l l y , be determined i n the f o l l o w i n g manner: The d i f f e r e n c e between the maleic anhydride adduct of c y c l o -pentadiene (IX) and the s u c c i n i c acid(XIV) would represent the a c t i v i t y of the methylene group i n IX. The carbon d i o x i d e produced i n the o x i d a t i o n of X I I I cannot be used f o r the measurement of the a c t i v i t y of the methylene group i n the cyclopentadiene(IX) because potassium permanganate o x i d a t i o n of c i s - c y c l o p e n t a n e - l , 3 - d i a m i n e ( X I I I ) would be expected t o cleave other parts of the r i n g . As the 1,4-and 2 , 3-positions are equivalent i n cyclopentadiene, then the d i f f e r e n c e i n r a d i o a c t i v i t y of XIV and XIX would represent the a c t i v i t i e s of the 1- and 4 - p o s i t i o n s of IX. The a c t i v i t y of XX, i s o l a t e d as barium carbonate, could be used as a check f o r the a c t i v i t y of the l $ 4 * p d s i t l g i i s . v * F i n a l l y , measurement of the a c t i v i t y ©f XIX would g i v e the a c t i v i t y of the 2 , 3 - p o s i t i o n s . A check f©r the a c t i v i t y of the methylene group, would be obtained by adding the a c t i v i t i e s of XIX and XX, and s u b t r a c t i n g t h i s value from the value obtained f o r IX. The complete s y n t h e t i c and degradation route l i s t e d above was done using " n o n - l a b e l l e d " compounds. Most of th© r e a c t i o n s were done at l e a s t t w i c e . Using carbon-14, the above work was repeated t o the ( c i s - t r a n s ) c y c l o p e n t a n e - l , 2 - d i o l ( V I ) . A number of attempts were made i n t r y i n g t o synthesize cyclopentadiene-C 1 4"; however they a l l f a i l e d , and l a c k of time prevented any f u r t h e r r e s e a r c h . 19. I n f u t u r e r e s e a r c h , more experimental d e t a i l s on the dehydration of ( c i s - t r a n s ) c y c l o p e n t a n e - l , 2 - d i o l have to be obtained f i r s t , before the Cl4-phase of the work can be completed t o shed some l i g h t on the s t r u c t u r e of the c y c l o -p entadienyl anion. EXPERIMENTAL (#) A. REAGENTS AND SOLVENTS Chloroform For i n f r a r e d measurements, reagent grade chloroform was shaken w i t h cone, s u l f u r i c a c i d , washed w i t h 3$ sodium bicarbonate s o l u t i o n and then w i t h water. The r e s u l t i n g chloroform was d r i e d f i r s t w i t h calcium c h l o r i d e , then w i t h calcium s u l f a t e , and f i n a l l y d i s t i l l e d . The f r a c t i o n c o l l e c t e d b o i l e d at 6l° (24). Ethanol For r e a c t i o n s i n v o l v i n g m e t a l l i c sodium, t h i s reagent was made "absolute" by the Lund and Bjerrum method (22). Ether For r e a c t i o n s i n v o l v i n g m e t a l l i c sodium or potassium, commercial "absolute" ether was d r i e d over sodium wire and then d i s t i l l e d from phosphorous pentoxide, b.p. 35°. E t h y l Oxalate Reagent grade as s u p p l i e d by Eastman Kodak, was shaken w i t h 3% sodium bicarbonate, washed w i t h water, d r i e d w i t h calcium s u l f a t e and vacuum d i s t i l l e d a t 42-44° at 0.6 mm. (#) A l l m e l t i n g points r e p o r t e d i n the present work, were obtained by h e a t i n g a copper b l o c k c o n t a i n i n g the sample and thermometer, and are uncorrected. 2 0 . Methanol When "absolute" methanol was needed, commercial reagent grade methanol was d r i e d and p u r i f i e d by the Lund and Bjerrum method ( 2 3 ) . Platinum Oxide C a t a l y s t f o r hydrogenations, was used as su p p l i e d by Brickman and Company. Alumina C a t a l y s t f o r dehydrations, i n p e l l e t s of approximately 3 mm. i n diameter, as su p p l i e d by The Harshaw Chemical Company. Sodium Ethoxide Prepared by adding f r e s h l y cut sodium t o an approximately t e n - f o l d excess of "absolute" ethanol i n a n i t r o g e n "dry-box". A r e f l u x condenser was then attached to the r e a c t i o n v e s s e l and under a slow stream of dry n i t r o g e n , the r e a c t i o n was allowed to proceed at room temperature. A f t e r the r e a c t i o n was complete (approx. 24 hrs.) the excess ethanol was removed at the water pump. To remove the a l c o h o l completely, the sodium ethoxide was d r i e d at 1 0 0 ° a t 0 . 1 mm. f o r approximately f o u r hours. C a r e f u l work w i l l r e s u l t i n a product which i s easy to powder, and white i n c o l o r . p-Toluenesulfonvl C h l o r i d e C. P. grade, as s u p p l i e d by Eastman Kodak, was p u r i f i e d by shaking a benzene s o l u t i o n w i t h % sodium hydroxide, washing w i t h water and vacuum d i s -t i l l i n g ( 2 5 ) . The product which c r y s t a l l i z e d i n the r e c e i v e r , had a m.p. of 6 8 . 5 ° . L i t . , 6 9 ° ( 2 5 ) . -E t h y l hydrazodicarboxylate Prepared from 8$% hydrazine hydrate and e t h y l ehloroformate ( 4 5 ) i n 8 3 $ y i e l d w i t h a m.p. of 1 2 7 . 5 - 1 3 0 ° . L i t . 131° ( 4 5 ) 21. E t h y l Azodicarboxylate Prepared by o x i d i z i n g e t h y l hydrazodicarboxylate w i t h c h l o r i n e gas(45 i n 57*2$ y i e l d . The product, a b e a u t i f u l orange-red l i q u i d , b o i l e d a t 104° at 11.0 mm. L i t . 111° at 15 mm.(45). Nitrosomethylurea Prepared by adding a 50$ sodium n i t r i t e s o l u t i o n t o a hot, p r e f i l t e r e d s o l u t i o n of methylamine hydrochloride and potassium cyanate, f o l l o w e d by the a d d i t i o n of c o l d 15$ s u l f u r i c a c i d t o t h i s s o l u t i o n at -5 to 0 ° (58). The s l i g h t l y cream color e d c r y s t a l l i n e product was f i l t e r e d o f f , thoroughly washed w i t h water and d r i e d over phosphorous pentoxide at 0.5 mm. pressure. The product stored at a p p r o x i -mately -15°» and protected from l i g h t , was s t i l l s t a b l e and usable s i x months l a t e r . B. SYNTHETIC AND DEGRADATIVE PROCEDURES T e t r a e t h y l Propane— 1 . 1.3.3-tetracarboxylate ( I ) (11) To a mixture of 320 gm. of f r e s h l y r e d i s t i l l e d d i e t h y l malonate and 84 ml. of 35$ formaldehyde, cooled to 2 ° i n an ic e - b a t h , was added 6.0 gm. of potassium c h l o r i d e and then 5.0 gm. of f r e s h l y d i s t i l l e d diethylamine. The components were w e l l shaken and then allowed to come to room temperature and thus kept f o r 16 hours w i t h o c c a s i o n a l shaking. The r e a c t i o n mixture was then heated on a steam bath f o r s i x hours, cooled to room temperature, the water separated o f f and the remaining l i q u i d vacuum d i s t i l l e d . The f r a c t i o n c o l l e c t e d b o i l e d at 143-1460 at 0.5 mm. and weighed 266.4 gm. (82.7$). 22. Glutaric Acid (II) (11) Into a three-necked flask, f i t t e d with a reflux condenser, stir r e r and thermometer, was placed 386.4 gm. of tetraethyl propane-1,1,3,3-tetracarboxy.late and 78O ml. of 50$ hydrochloric acid. With st i r r i n g , the reaction mixture was slowly refluxed u n t i l the mixture became homogenous (approx. six hours). The reaction mixture was then d i s t i l l e d under reduced pressure until the water and hydrochloric acid were removed. As ©n cooling the material i n the d i s t i l l a t i o n flask did not solidify, i t was further refluxed for two hours with 200 ml. of 50$ hydrochloric acid, and then the water and hydro-chloric acid removed under reduced pressure. On cooling, 147.0 gm. (104.5$) of crude glutaric acid was obtained. A small portion recrystallized twice from benzene, had a melting point of 95-96°, L i t . 97° (30). A mixed m.p. with authentical, once recrystallized glutaric acid showed no depression. Ethyl Glutarate (III) (42) Into a one-liter d i s t i l l a t i o n flask were placed 146.5 (1.11 moles) of crude glutaric acid, 400 ml. of absolute ethanol, 200 ml. of toluene and O.83 ml. of cone, sulfuric acid. The flask was connected to an ordinary d i s t i l l i n g apparatus and heated u n t i l the azeotropic mixture of ethanol, toluene and water began to d i s t i l at 75°. D i s t i l l a t i o n was continued u n t i l the b.p. of the d i s t i l l a t e reached 78°. The d i s t i l l a t e was dried with 170 gm. of anhydrous potassium carbonate, f i l t e r e d and returned to the d i s t i l l a t i o n flask which was again heated until the b.p. of the d i s t i l l a t e reached 80°. At this point vacuum d i s t i l l a t i o n was commenced. The product c o l l e c t e d b o i l e d at 112-119°, at 10-11 mm., and weighed 124.0 gm. (59.6$). In other rune, when the g l u t a r i c a c i d used was r e -c r y s t a l l i z e d from benzene, a y i e l d of 88.6$ of e t h y l g l u t a r a t e was obtained, b o i l i n g at I36-I37 0 at 32 mm., 1.4234. L i t . , 20 N D 1.4241; hp. 103-104° at 7 mm. (30). ^-?-Dicarboeth©xycyclopentadione-1.2 (IV) (17) To 88.0 gm. (1.29 moles) of e t h a n o l - f r e e , white sodium ethoxide, covered w i t h 500 ml. of anhydrous ether, con-t a i n e d i n a o n e - l i t r e round-bottomed f l a s k f i t t e d w i t h a r e f l u x condenser, 95.8 gm. (O.656 moles) of f r e s h l y r e d i s t i l l e d e t h y l oxalate was added. On mixing t h i s turned i n t o a pale y e l l o w i s h -orange c o l o r . Now 123.4 gm. (O.656 moles) of e t h y l g l u t a r a t e was added dropwise over a p e r i o d of 30 minutes, the r e a c t i o n mixture deepening i n c o l o r during t h i s a d d i t i o n . The mixture was r e f l u x e d f o r one hour, the ether d i s t i l l e d o f f , and the r e s i due heated to 125-130° f o r f o u r hours, when i t changed t o a yellowish-brown, dry cake. This residue was ground i n t o a f i n e powder and s l o w l y added to a w e l l s t i r r e d i c e - c o l d s o l u t i o n of 10$ s u l f u r i c a c i d , whereupon the e s t e r p r e c i p i t a t e d out as a cream-colored s o l i d . The p r e c i p i t a t e was washed w i t h i c e -c o l d water, f i l t e r e d , sucked dry on the Buchner f u n n e l and r e c r y s t a l l i z e d from approximately 500 ml. of 95$ e t h a n o l . The d r i e d c r y s t a l l i n e product weight was 110 gm. (69*2$) and had a m.p. of 115.5-116.5°• A small p o r t i o n of the e s t e r , r e c r y s t a l -l i z e d once more, had a m.p. of 116-117°. The l i t e r a t u r e r e p o r t s a m.p. of "near 118°, and a y i e l d of 50$. (17) 24. Cvclopentadione-1.2 (V) (31) In a o n e - l i t r e round-bottomed f l a s k equipped w i t h a r e f l u x condenser were placed 108.6 gm. (0.499 moles) of 3,5-dicarboethoxycyclopentadione-l,2, 400 ml. of 17$ s u l f u r i c a c i d and 20 ml. of eth a n o l . The mixture was r e f l u x e d f o r 110 mins., w i t h a bath temperature of 117°. The r e s u l t i n g s o l u t i o n turned reddish-brown i n c o l o r . A f t e r c o o l i n g (under n i t r o g e n ) , the s o l u t i o n was cont i n u o u s l y e x t r a c t e d w i t h ether f o r eleven hours. Maintained under an atmosphere of n i t r o g e n the ether was removed on a water bath and the product vacuum d i s t i l l e d . Cyclopentadione, which c r y s t a l l i z e d i n the r e c e i v i n g f l a s k , b o i l e d at 70-80° at 1.7-1.9 mm., and weighed 24.2 gm. (55.0$). I t melted at 54-55°. L i t . 56° (31). A i r very r a p i d l y decomposes t h i s d i k e t o n e i However, when sealed o f f under n i t r o g e n and kept at approximately 0° i t i s s t a b l e f o r a t l e a s t s i x months. On contact w i t h s k i n , prominent black spots form a f t e r some time, and remain f o r a long p e r i o d . Cvclopentane-1.2-diol (VI) Into a g l a s s - l i n e r was placed a s o l u t i o n of 12.5 § m« (0.128 moles) of cyclopentanedione - 1,2 i n 50 ml. of absolute ethanol and 0.104 gm. of platinum oxide. The l i n e r was placed i n a bomb whose t o t a l v o i d was 278 cc. The a i r was thoroughly f l u s h e d out of the bomb w i t h hydrogen. The bomb was then charged t o 500 p . s . i . w i t h hydrogen, and shaking commenced at room temperature. In one-half an hour the pressure dropped 280 p . s . i . , whereupon the bomb was recharged t o 400 p . s . i . 25. w i t h hydrogen and shaking recommenced. A f t e r 42 hours a t o t a l drop of 450 p . s . i . occurred. Complete hydrogenation r e q u i r e d a drop of 400 p . s . i . The c a t a l y s t was f i l t e r e d o f f , and the ethanol removed under reduced pressure at the water pump. A c l e a r , c o l o r l e s s , v i s c o u s l i q u i d was obtained. On c o o l i n g t o approximately -10° some c r y s t a l l i z a t i o n occurred, but on warming to 20° complete s o l u t i o n r e s u l t e d . The d i - p - n i t r o b e n z o a t e . prepared i n the r u s u a l manner, •was r e c r y s t a l l i z e d from et h a n o l , m.p. 90-104°. R e c r y s t a l l i z e d once more, m.p. 93 - 1 2 5 ° . L i t . , c i s - 117°; t r a n s - 145° (44) For i n f r a r e d a n a l y s i s some of t h i s hydrogenated product was vacuum d i s t i l l e d t w i c e , and made Into a 3.0% s o l u t i o n i n pure chloroform. ( F i g . 1, p. 37) Cyclopentadiene (VII) The dehydrating column c o n s i s t e d of a Pyrex tube, 30 cm. long and 22 mm. i J d . , wound e x t e r n a l l y i n a s p i r a l w i t h approximately 900 cm. of No. 27 Chromel-"A" w i r e . , A thermo-couple w e l l was constructed so tha t i t would r e s t i n the centre of the c a t a l y s t mass. To one end of the tube, an i n l e t was provided so that the substance t o be dehydrated and n i t r o g e n gas could be introduced simultaneously. To the " e x i t - e n d " of the tube, a narrower piece of g l a s s tubing was a f f i x e d , which i n t u r n could be connected to two consecutive "Dry-ice"-acetone cooled t r a p s . This tube was f i l l e d w i t h p e l l e t s of commercial 8-mesh alumina. With a slow stream of n i t r o g e n f l u s h i n g through, i t was heated at 4000 f o r approximately 48 hours to dry and 26. a c t i v a t e the c a t a l y s t . With the temperature at 400 i 3°, the e x i t end connected to the two uDry-ice"-acetone t r a p s , and a slow stream of n i t r o g e n f l u s h i n g through the tube, 2.47 gm. of trans-cyelopentane-l,2-diol was s l o w l y introduced i n t o the column over a p e r i o d of 10-15 minutes. The product, which possessed the very c h a r a c t e r i s t i c odor of cyclopentadiene, c o n s i s t e d of 0.4 ml. (21$) of a s l i g h t l y g r e e n i s h o i l f l o a t i n g on approximately one ml. of water. The maleic anhydride adduct of t h i s product, twice r e c r y s t a l l i z e d from ether had a m.p. of 161.5-162.5°. L i t . 165° (32). Potassium Cyclopentadienide ( V I I I ) Cyclopentadiene was generated' by sl o w l y r e f l u x i n g d icyclopentadiene and c o l l e c t i n g the d i s t i l l a t e at 44-46° (43). This m a t e r i a l was stored at "Dr y - i c e " temperature t o keep p o l y -m e r i z a t i o n at a minimum. Just before use the cyclopentadiene was r e d i s t i l l e d - b.p. 41-42°. The potassium used i n t h i s r e a c t i o n was handled i n the f o l l o w i n g manner: I n s i d e a box from which a l l a i r was d i s p l a c e d w i t h dry n i t r o g e n gas, the potassium was placed i n t o a deep mortar c o n t a i n i n g pure anhydrous benzene. The outer oxide-.coating was cut o f f , and the f r e s h l y cut metal t r a n s f e r r e d i n t o a tared, beaker c o n t a i n i n g anhydrous benzene. The r e q u i r e d potassium (10.7 gm.) was then introduced i n t o a 500 ml. round-bottomed f l a s k c o n t a i n i n g approximately 100 ml. of pure, anhydrous benzene. The f l a s k was then stoppered. The potassium scraps remaining i n the mortar were immediately decomposed by 27. the cautious a d d i t i o n of dry t e r t - b u t y l a l c o h o l . Small specks of potassium remaining on the k n i f e and tweezers were a l s o decomposed w i t h t e r t - b u t y l a l c o h o l . The f l a s k c o n t a i n i n g 11.0 gms. (0.282 moles) of potassium was unstoppered, and heated u n t i l the metal l i q u i f i e d . Once again the f l a s k was stoppered, wrapped i n a towel and sharply shaken three times. An e f f i c i e n t reflux-condenser was then attached t o the f l a s k i n place of the stopper, and w i t h dry n i t r o g e n s l o w l y sweeping i n t o the f l a s k , the contents were allowed t o come to room temperature. Then, without i n t r o -ducing a i r , a s o l u t i o n of 23.0 gm. (0.348 moles) of c y c l o -pentadiene i n 100 ml. of pure, anhydrous ether was s l o w l y added to t h i s f i n e granular potassium i n benzene. A f t e r the i n i t i a l r e a c t i o n had subsided, the mixture was r e f l u x e d f o r f o u r hours. The ether and benzene were removed under reduced pressure and the s l i g h t l y p i n k i s h s a l t f i n a l l y d r i e d a t 0.1 mm. at 60° f o r three hours. This dry s a l t , kept i n a well-stoppered f l a s k , was i s t a b l e f o r at l e a s t three months. Cyclopentadiene (IX) from Potassium Cyclopentadienide Into a 100 ml. round-bottomed f l a s k was placed 4.37 gm. of potassium cyclopentadienide, and then cooled to -80°. To t h i s c o l d s a l t , approximately 30 ml. of c o l d (-80°) concentrated h y d r o c h l o r i c a c i d was added, the contents i n the r e a c t i o n f l a s k being w e l l s t i r r e d . Twenty ml. of i c e - c o l d water was. next introduced, and the mixture d i s t i l l e d at a bath temperature of 60°. The r e c e i v e r c o l l e c t i n g the product was cooled i n "D r y - i c e " acetone mixture. Approx. 1.2 gm of cyclopentadiene was obtained. (43.3$). 28. A slow a d d i t i o n of 20 ml. of r e d i s t i l l e d butanol at j u s t above i t s f r e e z i n g point t o 24 gm. of potassium c y c l o -pentadienide, f o l l o w e d by a d i s t i l l a t i o n , using a r e f l u x condenser w i t h a jacket temperature of 50° as a column y i e l d e d 3*9 gm. (26$) of cyclopentadiene. D i e t h y l e s t e r of 2.3-dihydrazobicyclo (2.2.1.)-5-heotene-2. 3 - d i c a r b o x y l i c a c i d (X) (18) N.N-Dicarbethoxv-endomethylenetetra hydropvridazine I n a 250-ml. round-bottomed f l a s k equipped w i t h an e f f i c i e n t r e f l u x condenser were placed 3-9 gm. of the c y c l o -pentadiene obtained i n the l a s t r e a c t i o n and 11.0 gm. of cyclopentadiene obtained from d i c y c l o p e n t a d i e n e . Through the r e f l u x condenser 33.27 gm. of e t h y l a z o d i c a r b o x y l a t e i n 80 ml. of pure anhydrous ether was s l o w l y added. The r e a c t i o n mixture warmed up on t h i s a d d i t i o n . A f t e r r e f l u x i n g f o r approximately 12 hours, the r e s u l t i n g mixture was c o l o r l e s s , i n d i c a t i n g the disappearance of e t h y l a z o d i c a r b o x y l a t e . The ether was removed under reduced pressure, and the remaining very v i s c o u s , s l i g h t l y y e l l o w i s h l i q u i d was vacuum d i s t i l l e d , y i e l d i n g 43.9 gm. (96$) of product b o i l i n g at 109-112° at 0.2-0.25 mm.: Dibromo d e r i v . , m.p. 66.0-66*5° L i t . b.p. 120° at 0.5 mm.; dibromo derv., m.p.. 67° (18) ( D i - e t h y l e s t e r of 2 . V D i a z a b i c y c l o ( 2 . 2 . 1 ) heptane-2.^- a i c a r b o x y l i c acid) (XIO (18) Into a g l a s s - l i n e r were placed 11.55 gm. (0.0481 moles) of d i e t h y l e s t e r of 2,3-dihydrazobicyclo(22.2.1) 5-heptane-2, 3 - d i c a r b o x y l i c a c i d i n 38 ml. of absolute methanol and O.O87 gm. 29. of platinum oxide. The l i n e r was attached t o the hydrogenator w i t h a t o t a l v o i d of 4260 c c , and the a i r completely f l u s h e d out w i t h hydrogen. The l i n e r was then charged w i t h hydrogen t o 239 p . s . i . , and shaking commenced. The r e q u i r e d t h e o r e t i c a l drop of 4.1 p . s . i . occurred i n two hours, whereupon hydrogen-a t i o n was stopped, the l i n e r removed from the hydrogenator and the c a t a l y s t removed by f i l t r a t i o n . The product I n t h i s methanol s o l u t i o n was used" d i r e c t l y i n the next r e a c t i o n . I n a p r e l i m i n a r y run, 9-29 gm. of diethyl e s t e r of 2,3-dihydrazo(2.2.1) 5-neptene-2,3-dicarboxylic a c i d was hydrogenated at 22.00 p . s . i . A f t e r one hour 97$ of the t h e o r e t i c a l amount of hydrogen was absorbedj i n two hours hydrogenation was complete. Further hydrogenation f o r an hour r e s u l t e d i n no f u r t h e r drop I n pressure. The product was i s o l a t e d by f i l t e r i n g o f f the c a t a l y s t , removing the methanol at the w a t e r - a s p i r a t o r , and vacuum d i s t i l l i n g the r e s i d u e . The f r a c t i o n b o i l i n g at 115-117° at 0.9-1.0 mm. was c o l l e c t e d and weighed 7.80 gm. (84.3$) 2 T3-Diazablcyclo(2.2.1) heptane (Cuprous C h l o r i d e Complex) (XII) (18) To the methanolic s o l u t i o n of the d i e t h y l e s t e r of 2,3-diazabicyclo(2.2.1)heptane-2,3-dicarboxylic a c i d obtained i n the l a s t r e a c t i o n , 16.0 gm. of potassium hydroxide was added. The r e s u l t i n g s l i g h t l y y e l l o w i s h s o l u t i o n was g e n t l y r e f l u x e d on a water-bath f o r two hours. The potassium c a r -bonate, which formed I n the r e a c t i o n , was f i l t e r e d o f f , and 30. washed twice with 10 ml. of absolute methanol. The potassium carbonate, a f t e r drying, weighed 13.24 gm. (99.8$). The com-bined methanolic f i l t r a t e and washings was c a r e f u l l y evaporated off under reduced pressure and the residue was steam d i s t i l l e d . Steam d i s t i l l a t i o n was continued u n t i l no red color was produced when cupric chloride was added to a few drops of the d i s t i l l a t e . To the steam d i s t i l l a t e , 8.2 gm. (0.0481 moles) of cupric chloride dihydrate was slowly added with s t i r r i n g . The red cuprous chloride complexrimmediately started to pre-c i p i t a t e as long g l i s t e n i n g prisms. The next day t h i s red pr e c i p i t a t e was f i l t e r e d o f f , washed with 30 ml. of water, and dried at 0.1 mm. f o r two hours oyer phosphorous pentoxide. This dried product weighed 3*42 gm. (35$). In a week, a second crop was c o l l e c t e d . The t o t a l weight of product was 4.37 gm. (44.6$) (From d i e t h y l ester of 2,3-dihydrazobicyclo$2.2.1)-5-heptene-2,3-dicarboxylic acid) Anal. Calcd. f o r CjHS^.CuCl.^B^O 8 C l , 17.37 " " C5H8N.CUCI. : C l , 18.17 Found: C l , 18.01, 18.10 Cis-cyclopentane-1.^-diamine (Stannous Chloride Complex) (XIII)(18) A mixture of 2.707 gm. of the cuprous chloride com-plex of 2,3-diazabicyclo(2.2.1) heptane, 24.5 gm. of mossy t i n and 40 ml. of concentrated hydrochloric acid was heated i n a bo i l i n g water bath f o r 6.5 hours. Then to the s t i l l hot reac t i o n mixture, 10 ml. of concentrated hydrochloric acid was added. 31. After cooling to 60°, the re s u l t i n g mixture was f i l t e r e d through a $i,:nt.er-e.d:-«jlass Ct funnel. After standing at 5° over night, the long s i l k y needles were f i l t e r e d o f f . Drying over phosphorous pentoxide and sodium hydroxide p e l l e t s at 1.0 mm. fo r s i x hours i n a vacuum desiccator gave 5*563 gm. (74-.3$) of a product melting at 1 5 5 - 1 6 3 ° , L i t . 145-146° (46); 172° (18). Anal. Calcd. f o r C ^ H g C N R ^ .(SnCl 2)2.2HCl.H 20 : H, 4.91$ » " C5H8(NH 2)2(SnCl 2)2.2HCl : N, 5.07$ Found: N (Duma) 4.90, 4.97$ Succinic Acid (XIV) (46) To 5.06 gm. of the stannous chloride complex of cis-cyclopentane-l ,3-diamine dihydrochloride, a solu t i o n of 12.24 gm. of potassium permanganate i n 122.5 ml. of water was added. The mixture was refluxed i n a b o i l i n g water bath f o r 15 minutes and immediately cooled. The manganese dioxide was f i l t e r e d off and washed with water. The combined f i l t r a t e s , i f colored, were decolorized with sulfur dioxide and continuously extracted with pure ether f o r 60 hours. The ether from t h i s extract was evaporated, leaving a mixture of white and. s l i g h t l y yellowish c r y s t a l s . R e c r y s t a l l i z a t i o n from water (charcoal) yielded 0.109 gm. (9.7$) of product with a m.p. Of 176-J#d°. A small portion, r e c r y s t a l l i z e d twice more, had a m.p. of 179-1800. The reported m.p. of succinic acid i s 188° but the above once-recrystallized product did not depress the mixed m.p. with authentic succinic acid. 3 2 . M.p. of once r e c r y s t a l l i z e d commercial s u c c i n i c a c i d : 184 - 1 8 5 . 5 ° mixed m.p. : 184 . 5 - 1 8 6 ° Di-p-biomophenacyl e s t e r , m.p. 2 0 8 . 5 - 2 1 0 ° L i t . m.p. 2 1 1 ° ( 3 6 ) Dimethyl Succinate (XV)(7) (C h a r a c t e r i z e d as the Hydrazide) To a s o l u t i o n of 15 mgm. of s u c c i n i c a c i d i n approx-imate l y 4 . 5 ml. of methanol at 0 ° , a s l i g h t excess of d i a z o -methane i n c o l d ether was slo w l y added w i t h s w i r l i n g . A f t e r approximately 15 minutes the r e s u l t i n g s o l u t i o n was allowed t o come to room temperature and the ether, diazomethane, and methanol removed i n a stream of n i t r o g e n . To the e s t e r obtained i n the same t e s t - t u b e , used i n the above p r e p a r a t i o n 0.14 ml. of 85$ hydrazine hydrate was added together w i t h 5 drops of methanol. The contents of the tube were cooled i n a "Dry-ice"Qacetone mixture, the tube evacuated, sealed and then heated at 1 2 0 ° f o r one hour. A f t e r c o o l i n g , the tube was opened and the c r y s t a l l i n e product scraped out and pressed on f i l t e r paper to dry. R e c r y s t a l l i -z a t i o n from ethanol gave white c r y s t a l s which melted at 164-1 6 5 ° . L i t . 1 6 7 ° (14). The above c r y s t a l s , when mixed w i t h s u c c i n y l hydrazide obtained from a u t h e n t i c a l d i e t h y l s u c c i n a t e , gave a m.p. of 1 6 3 . 5 - 1 6 4 . 5 0 . S u c c l n v l Hydrazide (XVI) (9.14) Into a 20 ml. C^iius tube c o n t a i n i n g 1 . 0 0 gm. ( 0 . 0 0 | 6 9 moles) of e t h y l succinate at 0 ° , 0 . 5 9 ml. ( 0 . 0 1 0 3 moles) of hydrazine hydrate at Oo was added. The contents of the tube 33. were frozen out i n a ! ,Dry-ice"-acetone mixture, the tube evacuated, sealed, and then heated at 120° f o r one hour. The c r y s t a l l i n e product r e c r y s t a l l i z e d from ethanol weighed 0.77 gm. (91.6$), had a m.p. of 164 . 5 - 1 6 5 . 5 ° . L i t . l67°(l£). Ethylene Diurethan (XVII) ( H ) To 0.592 gm. of succinyl hydrazide i n a 100 ml. beaker, 6.0 ml. of lNKti^drochloric acid and 4 ml. of water were added. After the hydrazide dissolved, 10 ml. of ether was added and the mixture cooled to - 5 ° i n an i c e - s a l t hath. To t h i s cold mixture, 0.689 gm. of sodium n i t r i t e was slowly added with s t i r r i n g . The temperature of the reaction mixture was not allowed to r i s e above 2 ° . After the addition was completed, the mixture was well s t i r r e d and the ether layer separated. The aqueous layer was extracted once with 10 ml. of f r e s h ether and the combined ether extracts were shaken once with sodium bicarbonate,solution, f i l t e r e d , and then washed once with 15 ml. of water. The ether layer was separated, dried with calcium chloride f o r f i v e minutes and f i n a l l y with anhydrous calcium s u l f a t e . To t h i s dried ether sol u t i o n of succinyl azide placed i n an Erl§nmeyer f l a s k , 20 ml. of absolute ethanol was added, and the s o l u t i o n boiled gently on a hot plate. When the t o t a l volume was reduced to approxi-mately 1 ml. the Erlgnmeyer was transferred to a steam bath where evaporation was proceeded to dryness. This white c r y s t a l l i n e product weighed 0.145 gm. (17.5$) and had a m.p. of 1 0 6 . 5 - 1 0 8 ° . L i t . 110° (13) 34-. H y d r o l y s i s of Ethylene d i u r e t h a n (XVIII) (7) In a 30 ml. two-necked f l a s k , 130 mg. of ethylene-diurethane i n 6.0 ml. of 4 8 $ hydrobromic a c i d was r e f l u x e d f o r two hours w i t h a slow stream of C 0 2-free n i t r o g e n sweeping the system. This n i t r o g e n swept the carbon d i o x i d e generated i n the r e a c t i o n out through the condenser i n t o a gas d i s p e r s i o n tube immersed i n lN-carbonate f r e e sodium hydroxide s o l u t i o n . A d d i t i o n of 100 ml. of IN ammonium c h l o r i d e s o l u t i o n and 0 . 2 8 gm. of barium c h l o r i d e i n 20 ml. of water to the sodium hydroxide p r e c i p i t a t e d the BaCO^. This carbonate, a f t e r being f i l t e r e d through a g l a s s - s i n t e r e d c r u c i b l e ( M - p o r o s i t y ) , washed w i t h b o i l i n g wateraand absolute a l c o h o l and then d r i e d f o r one hour at 1 2 0 ° weighed 239 mgm. ( 9 4 . 8 $ ) . The contents of the r e a c t i o n f l a s k were evaporated j u s t t o dryness at room temperature under reduced pressure. Excess methanolic KOH was added, and the s o l u t i o n again d i s -t i l l e d to dryness, the d i s t i l l a t e c o l l e c t e d i n a r e c e i v e r cooled i n a "Dry-ice"-acetone mixture. Hydrogen c h l o r i d e was bubbled i n t o the d i s t i l l a t e , and the r e s u l t i n g p r e c i p i t a t e was f i l t e r e d o f f . R e c r y s t a l l i z e d from water-methanol, the ethylene diamine d i h y d r o c h l o r i d e , a f t e r d r y i n g over P2O5 a n d KOH p e l l e t s , weighed 70.9 mgm. ( 8 5 $ ) . P i c r a t e , r e c r y s t a l l i z e d from absolute et h a n o l , melted w i t h dec. at 229.5-232°. L i t . 2 3 0 - 2 3 5 ° (33) Cyclopentanone (57) 35. Two hundred gm. of powdered a d i p i c a c i d and 10.0 gm. of powdered Ba(0H)2 were thoroughly mixed and then heated at 300° i n a s a l t - h a t h . The crude cyclopentanone and water d i s t i l l e d over at 101-102°. The d i s t i l l a t e was saturated w i t h anhydrous K2CO3. The cyclopentanone was separated, d r i e d w i t h anhydrous CaCl2, and d i s t i l l e d through a short column to y i e l d 886 gm. (77.1$) of a cyclopentanone b o i l i n g at 128-129° at atmospheric pressure. Cyclopentanol (SXI) (47) Cyclopentanone (88 gm., 105 moles) was s l o w l y added, over a period of 105 minutes, to a w e l l s t i r r e d suspension of 12.3 gm. (0.324 moles) of l i t h i u m aluminum hydride I n approx. 300 ml. of pure, anhydrous ether. The r e a c t i o n mixture was then r e f l u x e d f o r one and a h a l f hours. C a u t i o u s l y , wet ether was then introd u c e d , f o l l o w e d by c o l d 10$ H 2 S O 4 , u n t i l most of the i n o r g a n i c s o l i d s d i s s o l v e d and two d i s t i n c t phases formed. This mixture was then continuously e x t r a c t e d w i t h ether f o r 20 hours, and the r e s u l t i n g ether e x t r a c t d i s t i l l e d . The f r a c t i o n b o i l i n g at 124-128© was c o l l e c t e d . This d i s -t i l l a t e d r i e d w i t h CaS04 and r e d i s t i l l e d y i e l d e d 38.8 gm. (43.5$) of cyclopentanol b o i l i n g at 138-139.5°. Cyclopentene (XXII) (16) I n a 250 ml. two-necked f l a s k , equipped w i t h a separatory f u n n e l and a 20 cm. lo n g , four-necked Wurtz column f i l l e d w i t h pieces of g l a s s tubing (5 mm. long and 6 mm. i n diameter), was placed 1 5 . 0 gm. of 85$ phosphoric a c i d . The column was attached to a condenser, and the r e c e i v i n g f l a s k was heated to 1 7 3 ° , using a s a l t - b a t h of potassium n i t r i t e and potassium n i t r a t e . From the dropping f u n n e l , over a period of two hours, 4 3 . 0 gm. of cyclopentanol was slow l y added. A f t e r t h i s a d d i t i o n , the bath temperature was r a i s e d to 200° and maintained at 200° f o r 40 minutes. The temperature of the d i s t i l l a t e d i d not r i s e above 8 5 ° during the whole op e r a t i o n . The d i s t i l l a t e was d r i e d w i t h anhydrous calcium c h l o r i d e , then w i t h anhydrous calcium s u l f a t e . The . d r i e d d i s t i l l a t e was d i s t i l l e d through a 25 em. long - 1 cm. i . d . eolumn, packed w i t h 4 mm. g l a s s h e l i c e s , y i e l d i n g 3 2 . 0 gm. (95:*9$) of product b o i l i n g at 42 - 4 4 ° . L i t . 46©. T r a n s - c y c l o p e n t a n e - 1 . 2 - d i o l (XXIII) (44) In a 3-necked, 1 - l i t r e f l a s k , equipped w i t h a condenser, dropping f u n n e l and s t i r r e r , was placed 31*5 gm. ( 0 . 4 6 4 moles) of cyclopentene. C o n t r o l l i n g the temperature of the r e a c t i o n mixture so that only s l i g h t r e f l u x i n g was obtained, a mixture of 207 gm. of 30$ hydrogen peroxide (0..?41/}moles) and 558 gm. of 90$ formic a c i d (PQ:°w moles) was slow l y added w i t h s t i r r i n g through the dropping f u n n e l . 3 7 . A f t e r t h i s a d d i t i o n was complete, the r e a c t i o n mixture was kept at 40° f o r f o u r hours. The next day, the formic a c i d and water were removed under reduced pressure (water a s p i r a t o r ) . The remaining o i l was d i s s o l v e d i n approximately 1 0 0 ml. of 1 2 $ sodium hydroxide, and then r e f l u x e d f o r 40 minutes. To the contents of the r e a c t i o n f l a s k , d i l u t e s u l f u r i c a c i d was added u n t i l the mixture was j u s t s l i g h t l y b a s i c ( p H . 8 ) . The water was d i s t i l l e d o f f under reduced pressure and the remaining o i l was vacuum d i s t i l l e d . The product, which had a b.p. of 1 1 0 - 1 1 3 ° at 2 - 3 mm., weighed 2 6 . 4 gm. ( 5 5 - 9 $ ) . Di-p-nitrobenzoate, c r y s t a l l i z e d from e t h a n o l , m.p. 1 4 1 . 5 - 1 4 2 . 5 ° . L i t . 143° (44). , f # " "i.0 5.0 1.C ?.o y u TO 19.0 lit l*i \ I ' \h J—[°* \ w ! U' T R f i « s < (xxvi) / \F il y\Jj 1 / s 1 6 HYDRttENATED ° (vl) .*« \ i \j ieoo c m - i looo 2DOC I I H ' tut *«o - itno im an P i g . 1 . — I n f r a r e d spectrum of ( c i s - t r a n s ) cyclopentane-1 , 2 - d i o l , ( V I I ) , and t r a n s - c y c l o p e n t a n e - l , 2 - d i o l (XXVl), as Z% s o l u t i o n s i n chloroform. The a n a l y s i s was done by E. H. P o l , of the B r i t i s h Golumbia Research C o u n c i l . BIBLIOGRAPHY 38 1. A l d e r , K. and H o l z r i c h t e r , H. Ann. 524: 145. 1936 2. Armit, J . W. and Robinson, B. J . Chem. Soc. 1604. 1925 3. Armstrong, H. E. Proc. Chem. Soc. (London). 2 5 8 . 1887 4. Baeyer, E. Ann. 245: 1 0 3 . 1888; 251« 2 8 5 . I889 5. 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