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Pyrolysis and photolysis of cis and trans-3, 5-dimethyl-3-acetyl-delta1-pyrazoline and cis and trans-3,5-dimethyl-3-carbomethoxy-delta1-pyrazoline. Chiu, Norman Wing Kwai 1964

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PYROLYSIS AND PHOTOLYSIS OP ois  AND t r a n s - 3 , 5 - D I M E T H Y L - 3 - A C E T Y L - A -PYRAZOLINE AND 1  o i s AND  trans-3,5-DIMETHYL-3-CARBOMETHOXY-A -PYRAZOLINE 1  by NORMAN WING KWAI CHIU B.Sc., D a l h o u s i e U n i v e r s i t y ,  A THESIS SUBMITTED  1962  IN PARTIAL FULFILMENT OF  THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in  t h e Department o f CHEMISTRY  We a o p e p t t h i s  thesis  to t h e required  as ponforming standard  THE UNIVERSITY OF B R I T I S H COLUMBIA J u l y , 1964  In the  r e q u i r e m e n t s f o r an  British  mission  for reference  for extensive  p u r p o s e s may  be  cation.of  this  that  and  by  degree at  the  Library  written  Department  of  this  the. Head  U n i v e r s i t y of •  shall  permission,.  CHEMISTRY Columbia/  thesis for  o f my  I t i s understood  The U n i v e r s i t y . o f B r i t i s h V a n c o u v e r ' 8 , Canada  the  f u l f i l m e n t of  make i t f r e e l y  s t u d y * .I f u r t h e r a g r e e  thesis for financial  w i t h o u t my  Date  thesis i n partial  c o p y i n g of  granted  representatives.  this  advanced  Columbia,, I a g r e e  available  his  presenting  Department  shall  per-  scholarly  that;copying  gain  that  not  or  by  or p u b l i be  allowed  - i i -  ABSTRACT  The t h e r m a l and p h o t o l y t i c  decomposition  o f c i s and  t r a _ n s _ - 3 , 5 - d i m e t h y l - 3 - a c e t y l - A " " - p y r a z o l i n e have b e e n f o u n d t o 1  g i v e s i x p r o d u c t s . They have b e e n s e p a r a t e d and i d e n t i f i e d 2,3,5-trimethyl-/£-dihydrofuran,  c i s and  trans-1,2-dimethyl-l-  a c e t y l e y c l o p r o p a n e , c i s and t r a n s - 3 - m e t h y l - 3 - h e x e n - 2 - o n e 3 - m e t h y l - 4 - h e x e n - 2 - o n e . The f o r m a t i o n o f e y c l o p r o p a n e s photolysis pyrolysis  showed some d e g r e e  of s-tereospecifIcity.  and p h o t o l y s i s y i e l d e d  as  and  by  Both  o l e f i n s w i t h h i g h degree  of  2  stereospecificity. product  2,3,5-TrImethyl-££"-dihydrofuran  to eyclopropanes gave r e s u l t s  gave a h i g h e r r a t i o  of olefins  than p h o t o l y s i s . These decomposition  analogous  a major  of cis-3,5-dimethyl-3-acetyl-  from the decomposition  A -pyrazoline only. Pyrolysis  was  t o t h o s e o f c i s and  reactions  trans-3,5-dimethyl-  3-earbomethoxy-^-pyrazoline. The p r o d u c t photolysis  compositions  from both the p y r o l y s i s  o f c i s and t r a n s _ - 3 , 5 - d i m e t h y l - 3 - c a r b o m e t h o x y - ^ " -  p y r a z o l i n e have been found  t o show a s m a l l and r e g u l a r  ence o f t h e s o l v e n t and t h i s has b e e n r e l a t e d constant olefin in  of the solvent. P y r o l y s i s  to cyclopropane r a t i o  f o r m a m i d e , and  7*93  A small kinetic pyrolysis  and  and  of  5*95,  to the  and p h o t o l y s i s  57*43  and  21*79*  respectively,  solvent effect  dielectric  gave a n respectively,  i n cyclohexane.  has b e e n o b s e r v e d  of 3,5-dimethyl-3-carboraethoxy-/^-pyrazoline.  r a t e of p y r o l y s i s  influ-  a s . f o l l o w e d by t h e r a t e o f n i t r o g e n  f o r the The evo-  -Ili-  l u t i o n has  been found to decrease f o r the  solvents« d l - n - b u t y l  ether,  tetralin,  a m i d e . T h e s e r a t e s were a l l w i t h i n absence of r a t e constant  has  mediate i n these Liquid  an  -55  an  dielectric ionic  Inter-  phase p h o t o l y s i s  of  trans-3,5-dimethyl-3-carbotemperatures ranging  from  _.o t o 58  solvent  d i d not  show a p p r e c i a b l e  temperature t h e r e f o r e  q u e n c h i n g o f any  "hot"  Photolysis  and  give  reactions No  the do  influence  does not  the  composition. This  conditions  between t h e  p y r o l y s i s and  These r e s u l t s are  did  c i s and  trans-3,5-dimethyl-  photolysis  discussed  of the  shown  pyrazolines.  f o r the  I n view o f c u r r e n t  p y r o l y s i s and  by  trans-pyrazoline. mecha-  *1 proposals  two  Intermediate.  L  nistlc  of  suggested the  3 - c a r b o m e t h o x y - A - p y r a z o l i n e s ; h a s b e e n o b s e r v e d as partial  amount  The  trans-3,5-dimethy1-  under i d e n t i c a l  h a v e a common  isomerization  product  of temperature.  effect  p y r o l y s i s o f c i s and  same p r o d u c t not  change i n t h e  intermediate.  3-carbomethoxy-A - p y r a z o l i n e  the  The  reactions.  compositions a t t r i b u t a b l e to the  not  of high  of  form-  a f a c t o r of three.  argument a g a i n s t  methoxy~£^-pyrazolIne at v a r i o u s o  series  n i t r o b e n z e n e and  enhancement i n a s o l v e n t  b e e n u s e d as  following  photolysis  of &  -  -  vili  ACKNOWLEDGEMENT  The  author wishes t o express h i s s i n c e r e  t o D r , D. E . M e G r e e r who^ s u g g e s t e d t h i s and  appreciation  research  u n d e r whose g u i d a n c e a n d encouragement t h i s  project  research  was  performed. The  author Is indebted  Horn f o r t h e n u c l e a r  to Mrs. E. B r i o n  a n d Mr. P.  magnetic resonance s p e c t r a ,  B e r n h a r d t , M r s . A. A l d r i d g e  a n d M r s . C. J e n k i n s  t o D r . A. for the  microanalyses. Financial Council  o f Canada  appreciated.  assistance for this  from t h e N a t i o n a l research  project  Research  i s deeply  _ iv -  TABLE OF CONTENTS Page I. II,  Introduction  1  S y n t h e s i s and I d e n t i f i c a t i o n  o f 3,3 , , 5 - T r i s u b s t i t u t e d  /5^-Pyrazolines  1 1. c i s a n d  trans-3,5-dimethyl-3-carbomethoxy-  pyrazoline  7  2. c i s and t r a n s - 3 , 5 - d i m e t h y l - 3 - a c e t y l - A - p y r a z o l i n e .. 1  III.  S e p a r a t i o n and I d e n t i f i c a t i o n  of Products  f r o m t h e De-  composition of 3,5-DImethyl-3-aeetyl-A ~pyrazolines 1  IV. Decomposition  ... 13  o f 3 , 3 , 5 - T r i s u b s t i t u t e d Z ^ - P y r a z o l i n e s .. 21  V. D i s c u s s i o n VI.  9  30  Experimental 1. G e n e r a l s t a t e m e n t  4l  2. N - N i t r o s o - N - e t h y l u r e a  41  3. D i a z o e t h a n e  42  4. M e t h y l  I s o p r o p e n y l ketone  43  5. S ^ - D i m e t h y l - S - a c e t y l - ^ - p y r a z o l i n e  43  6. S e p a r a t i o n o f e i s and  tr_ans_-3,5-dimethyl-3-  acetyl-^-pyrazoline 7. S e p a r a t i o n o f c i s and  44 trans-3,5-dimethyl-3-  carbomethoxy-^-pyrazollne 8.  44  trans-3,5-Dimethyl-3-carbomethoxy-A^-pyrazollne hydrobromide  9. T h e r m a l p y r o l y s i s  45 of  3,5-dimethyl-3-acetyl-  AJ"-pyrazoline 9a. 2 , 4 - D i n l t r o p h e n y l h y d r a z o n e s  46 59  -  V  -  Page 10.  Thermal  p y r o l y s i s o f c i s and t r a n s - 3 , 5 - d i m e t h y l -  3-acetyl-A -pyrazoline  50  1  11.  Vapor  p h a s e p y r o l y s i s o f c i s and t r a n s - 3 , 5 - d i m e t h y l -  3-acet.yl-^"-pyrazoline 12.  50  L i q u i d phase p y r o l y s i s o f 3 , 5 - d i m e t h y l - 3 -  1 51  acetyl-A -pyrazoline 13.  L i q u i d phase p y r o l y s i s o f c i s a n d  trans-3,5-  dimethyl-3-aeetyl-^"-pyrazoline 14.  Photolysis  15.  P h o t o l y s i s o f c i s and  52  o f 3,5-dimethyl-3-acetyl-£J['-pyrazoline  ••••  trans-3,5-dimethyl-353  acetyl-^"-pyrazoline 16.  Vapor  phase p y r o l y s i s o f c i s and t r a _ n s - 3 , 5 - d i -  methyl-3-earbomethoxy-Z^-pyrazoline 17.  53  L i q u i d p h a s e p y r o l y s i s o f c i s and t r a n s - 3 , 5 - d i methyl-3-carbomethoxy-^"-pyrazoline  i n various 53  solvents 18.  20.  trans-3*5-dimethyl-3-carbomethoxy-  Photolysis of ^"-pyrazoline  19.  Photolysis  at various  o f c i s and  5^  temperatures  trans-3,5-dimethyl-3-carbo-  methoxy-^"-pyrazoline  i n Formamide a t 23°  Partial  trans-3,5-dimethyl-3-carbo-  pyrolysis of  56  56  methoxy-^-pyrazoline 21.  Partial  l i q u i d phase p y r o l y s i s o f t r a n s - 3 , 5 - d i -  methyl-3-carbomethoxy-/£"-pyrazoline 22.  52  Kinetic studies  of the pyrolysis of 3,5-dimethyl-3-  carbomethoxy-/^-pyrazoline BIBLIOGRAPHY  57  i n various  solvents  .......  57 60  - vi-  L I S T OF FIGURES Figure  Page  I . Mechanism o f ^ - p y r a z o l i n e II. III.  1  formation  I o n i c mechanism f o r t h e p y r o l y s i s 3-carbomethoxy-A - p y r a z o l i n e s Products from the p h o t o l y s i s earbomethoxy-^s-pyrazolines  of  of 3,4-dimethyl,  3  3*4~dimethyl-35  I V . N.m.r. a b s o r p t i o n showing.,the s e p a r a t i o n o f 3*5dimet.hyl-3-carbomethoxy-^-pyrazoline into i t s c i s and t r a n s isomers  8  V. N.m.r. s p e c t r a o f t r a n s - 3 , 5 - d l m e t h y l - 3 - e a r b o m e t h o x y &t-pyrazoline showing s p l i t t i n g s o f C ^ - h y d r o g e n s .... 12 V I . Products from t h e decomposition o f earbomethoxy-Zr-pyrazolInes  3,5-dimethyl-313  V I I A . P r e p a r a t i v e vapor chromatogram showing t h e s e p a r a t i o n o f products from the decomposition o f 3*5-dimethyl-^-pyrazolines  lh  V I I B . A n a l y t i c a l v a p o r phase c h r o m a t o g r a m s h o w i n g t h e s e p a r a t i o n o f 3-methyl-4-hexen-2-one and t r a n s 1,2-dimethyl-l-aeety.lcyclopropane  14  VIII.  Products from t h e decomposition o f 3,5-dimethyl3-acetyl-£r-pyrazolines  15  2 I X . N.m.r. s p e c t r u m o f 2 , 3 , 5 - t r i m e t h y l - & - d i h y d r o f u r a n X. S t e r e o c h e m i s t r y o f t h e f o r m a t i o n o f o l e f i n s f r o m ^•-pyrazoline XI. Apparatus  .. 17 38 55  f o r p h o t o l y s i s a t low t e m p e r a t u r e  X I I . F i r s t o r d e r p l o t o f l o g ^/(V^-V^.) v e r s e s time f o r the p y r o l y s i s o f 3,5-dimethyl-3-carbomethoxy-^s pyrazoline i n various solvents L  58  ~ v i i -  L I S T OP TABLES Table  Page  I . N.m.r. d a t a o f c i s and  trans_-3,5-»diraethyl-3-acetyl-  A ^ ~ p y r a z o l i n e and c i s and  trans-3 5-dimethyl-33  11  carbomethoxy-£i"~pyrazoline II.  Product  compositions  f o r the decomposition of  3,5-dimethyl-3-acetyl-/^-pyrazolines III.  Product  compositions  ' 22  f o r the decomposition  o f 3<>523  dimethyl-S-carbomethoxy-^-pyrazollnes IV. Product  compositions  o f c i s and pyrazoline V. Product  f o r the sealed-tube  pyrolysis  trans_-3,5-dimethyl-3-carbomethoxy-£^i n various  compositions  s o l v e n t s a t 125 of photolysis  o  , 2o  o f c i s and  trans-3,5-dimethyl-3-carbomethoxy-ft''-pyrazoline  27  - 1 -  I.  The  INTRODUCTION  a d d i t i o n of diazoalkanes  compounds t o f o r m A ^ - p y r a z o l i n e s these A^-pyrazolines  t o form  t o o(,/3-unsaturated  (1-5)  and  cyclopropanes  carbonyl  the p y r o l y s i s (6,7)  known f o r many y e a r s . B o t h t h e a d d i t i o n and  of  have been  pyrolysis  mecha-  nisms have been the s u b j e c t o f d i s c u s s i o n . I n p a r t i c u l a r , meehanism f o r t h e p y r o l y s i s settled  at  The Huisgen  of A^-pyrazolines  is still  not  recently,  by  the  present. a d d i t i o n mechanism has  and  addition,  coworkers  been proven  (8-10) t o be  a one-step m u l t i p l e - c e n t e r  s i m i l a r to the 1,3-dlpolar a d d i t i o n r e a c t i o n , r a t h e r  than the two-step i o n i c  mechanism  (6,11) p r e v i o u s l y  proposed.  T h e s e r o u t e s t o p y r a z o l i n e s a r e shown i n F i g u r e I . I t has R  •  1  R  also  2  CT  R  R  \  ,one-step  R  1  C=C  s  R  l^Y  1  !  X  J R< R*  Y  J  H  R two-step  RCHN^  R — —H , —CH3 Y —-.COCH3, -COOCH3  R  1  R^f— W  2  "^Y  R^ N^ X  III  ^N II  FIGURE I - Mechanisms o f A * - p y r a z o l i n e 1  b e e n shown alkane  (6,7)  formation,  t h a t the carbon o^to the n i t r o g e n In the diazo-  adds t o t h e d o u b l e  bond a t t h e c a r b o n  0 to the  carbonyl  - 2 -  group  (6,7)  i n the o l e f i n . C I s - a d d i t i o n  a c t i o n of diazomethane w i t h methyl angelate  The  (VI and V I I )  and  mixture no  also  olefins  consisting  cyclopropane  c o n t a i n e d t h e c o r r e s p o n d i n g A - p y r a z o l i n e (20) 2  (3,2l) a t a l l .  formation both ionic  Few  or  s t u d i e s have b e e n made t o d e t e r -  (6,11,12)  and  r e a c t i o n s . From l i m i t e d diradical  nisms f o r the t h e r m a l d e c o m p o s i t i o n  In-  (20,22-24) mecha-  o f ^ - - p y r a z o l i n e s have b e e n  t o e x p l a i n t h e s e p r o d u c t s . T h e s e p r o p o s a l s were made  on t h e a s s u m p t i o n  that  eyclopropanes  a r e formed  of the geometry p r e s e n t In the o r i g i n a l observations of p a r t i a l  and  complete  ed g e o m e t r y have b e e n r e p o r t e d Auken and R i n e h a r t r e p o r t e d (12)  loss  (12,21,25). that  ( X I ) , methyl  1.00.1.22*1.16:©.155 and s i m i l a r l y ,  F o r example, of  (VII) g i v e s  transcis-1,2-  (XIII) In the  XI, XII,and  ratio  X I I I i n the  1.00X0.70*3.73*0.24. These a u t h o r s have s u g g e s t e d mechanism  van  cis-3,4-dimethyl-3-carbo-  (VI) g i v e s X,  following modified ionic  mention-  2,3-dimethyl-2-butenoate  2,3-dimethyl-3-butenoate  methoxy-^-pyrazoline  Recent  (X), t r a n s - 1 , 2 - d i m e t h y l - l -  dimethyl-l-carbomethoxycyclopropane  ( X I I ) and m e t h y l  retention  o f t h e above  the p y r o l y s i s  1  carbomethoxycyclopropane  with  pyrazolines.  3,4-dimethyl-3-earbomethoxy-A -pyrazoline  ratio  of  been r e -  i n some i n s t a n c e s , w h i l e i n o t h e r s t h e  mine t h e mechanism o f t h e p y r o l y s i s  proposed  methyl  o f A ^ - p y r a z o l i n e s has  a product mixture  (6,7,13-19)  olefins  (IV) and  (12).  respectively  thermal decomposition  ported to y i e l d  tiglate  trans-3,4-dimethyl-3-carbomethoxy-  (V) t o g i v e c i s and  £^-pyrazoline  i s i n d i c a t e d by t h e r e -  the  (Figure I I ) , which postu-  - 3 -  COOCH, H  COOCH,  6  GH  H 03  COOCH,  3  .N  H  VI  (methyls c i s ) o r  VIII H C*  . ~COOCH  3  VII  (methyls t r a n s )  -N,  3  XI H-.C  H H-^C^  CH,  CH-,  3 \  OOCH,  H-C*' 3  c=c  N  /  3  C00CH  3  o  XII  +CH,  IX  E  /  2 \  H„C  /  H  3  C—CH COOCH,  XIII FIGURE I I - I o n i c  mechanism f o r t h e p y r o l y s i s  3,4-  of  dimethyl-3-carbomethoxy-£i-pyrazolines. lates ate  that r o t a t i o n occurs i n the diazonium betaine intermedi-  ( V I I I ) , and t h u s r a c e m i z a t i o n a t t h e a n i o n c e n t e r c a n t a k e  p l a c e . The s l i g h t 1.00  degree o f s t e r e o s e l e c t i v i t y ,  1 . 0 0 * 0 . 7 0  i n f a v o r o f t h e c i s - e y e l o p r o p a ne X  f r o m t h e c i s - p y r a z o l i n e V I , was  e x p l a i n e d by t h e s u g g e s t i o n  t h e l o s s o f n i t r o g e n i n g o i n g from V I I I t o IX i s s l i g h t l y  f a s t e r t h a n t h e r o t a t i o n i n V I I I due t o t h e f a c t ter  Is, 1 . 2 2 *  i n f a v o r o f the t r a n s - e y e l o p r o p a n e XI from the t r a n s -  p y r a z o l i n e V I I and  that  that  Involves consecutive eclipsed  that  the  lat-  i n t e r a c t i o n of methyl-carbo-  - 4 -  methoxy and rier  methylenediazonium-methyl which provides  to r o t a t i o n . I n s p i t e of the  f o r the  p r o p o s e d common- i n t e r m e d i a t e  p y r o l y s i s of p y r a z o l i n e s  propanes t o o l e f i n s are c i s - p y r a z o l i n e VI  VI  and  VII,  f o r the  loss  VIII  from V I I I ,  to pyrazolines  i t was  VI  shown t h a t  partial  gives  arrangement  (12).  the  validity  of t h i s  Ionic  ^-pyrazoline  of  stereospecifically cyclopropane  needs f u r t h e r  VII)  c i s and  has  r e s p e c t i v e l y , and  and  methyl angelate  (V)  respectively  and  van  plain  o f bonds N N -N 1  2  are  1 - C r -5  and  N 2- 0 3 o  o  w o u l d be and  the  the  geometry which i s present  the  stereospecifie regeneration  transition  re-  Therefore  thermal  decom-  (.12)  to  give  III).  (IV)  Rinehart  (V)  s t a t e XV.  could  i n which the o f bonds  The  breakage C  0  3- C j -5  and  pyrazolines. Similarly,  of methyl t i g l a t e  on  ex-  e y c l o p r o p a n e s formed r e t a i n  i n the  t h e n be  Therefore  XIV  of ^ " - p y r a z o l i n e s .  formation  s i m u l t a n e o u s , hence the  methyl angelate  no  methyl t i g l a t e  (Figure  of p h o t o l y s i s  state involved n  nitrogen  have p r o p o s e d a m o l e c u l a r mechanism t o  these observations  transition  the  trans-l,2-dimethyl-l-carbomethoxy-  XI)  (12)  of  examination.  been r e p o r t e d  (X and  Auken  VII.  trans_-3,4-dimethyl-3-carbomethoxy-  c i s -and  (VI and  sample  mechanism f o r t h e  p o s i t i o n of ^ - p y r a z o l i n e s Photolysis  pyrazoline  the  p y r o l y s i s of c i s -  L  recovered  eyclo-  for  f a s t e r than  3 , 4 ~ d i m e t h y l - 3 - c a r b o m e t h o x y " - £ - p y r a z o l i n e . (VI) In the  of  2 3.97  conversion  or VII  the  ratio  trans-pyrazoline  A l t h o u g h t h i s mechanism w o u l d p r e d i c t t h e intermediate  the  i s , .1.70  d i f f e r e n t , that  2.22°-1.31  and  some b a r -  (IV)  and  explained  through a s i m i l a r  the  of these  basis  photolysis  _ 5 -  results, he  the photolysis  of A^-pyrazolines  h a s b e e n assumed t o  stereospecific i n general. H  H  £OOCH, .COOCH,  H C3  H. C 5  \  /  /=\  0  X  IV  H C 3 \  _CH,  0  / N  XI  VII  Q  CH 3  3  VI  COOCH J  .C00CH 3  CH  o  3  V  FIGURE I I I - P r o d u c t s f r o m t h e p h o t o l y s i s  of 3,4-di-  methyl-3-carbomethoxy-,&?--pyrazolInes.  COOCH 3  H  3  V \/  OOCH,  3  xv  XIV In  this  H,  H 0- I  A  laboratory  ( 2 6 ) h a s shown t h a t  however, a p r e l i m i n a r y  the photolysis  reactions  3,5-dimethyl-3-earbomethoxy-£ -pyrazoline L  investigation  o f c i 3 and t r a n s -  (XVI a n d X V I I )  give  m i x t u r e s o f c y c l o p r o p a n e s , w i t h some l o s s o f s t e r e o s p e c i f i c i t y , and  o l e f i n products.  N  GOOCH, H  JCO0CIL  3  H C  H.  3  XVI  1-  fS)H  3  XVII  6  With the f i n d i n g pyrazolines  that  c i s and t r a n s - S ^ - d i a l k y l - A 1  c o u l d he s e p a r a t e d b y f r a c t i o n a l  distillation, a  new s y s t e m f o r s t u d y i n g t h e s t e r e o c h e m i s t r y h a s become a b l e . Thus, t h e purpose o f t h e present examine t h e t h e r m a l a n d p h o t o l y t i c  investigation  avail-  i s to  decompositions o f c i s and  trans-3,5-dimethy1-3-carbomethoxy-pyrazo1ine  (XVI a n d X V I I )  and t h e i r a n a l o g s , e i s a n d t r a n s - 3 , 5 - d i m e t h y l - 3 - a c e t y l - A 1  pyrazoline  ( X V I I I a n d XIX) i n an a t t e m p t t o f i n d  o u t more  i n f o r m a t i o n about t h e s e r e a c t i o n s . ,COCH  XVIII  ,COCH  XIX  3  _ 7 -  II.  SYNTHESIS AND  3,3,5-  IDENTIFICATION OF  TRISUBSTITUTED A -PYRAZOLINES 1  II-l.  trans-3,5-dimethyl-3-carbomethoxy-£r-pyrazoline  c i s and (XVI and  XVII)  3,5-Dimethyl-3-carbomethoxy-/S -pyrazoline L  by t h e a d d i t i o n ether  (17)  has b e e n shown by n.m.r. a n a l y s i s  C00CH  prepared  o f m e t h y l m e t h a c r y l a t e (XXI) t o d i a z o e t h a n e i n  m i x t u r e o f t h e two H  (XX)  40^60  t o be a  p o s s i b l e geometric isomers. Separation of COOCH„  3  3  o  H  XXI this  XX  mixture  ( F i g u r e IV) b y f r a c t i o n a l  N e s t e r and F a u s t 1 8 - i n c h by 6-mm. lower b o i l i n g fraction and  of  fraction  99+$  up t o 93$  purity.  i s o m e r was  i s o m e r was  t h e 60$  N.m.r. a n a l y s e s o f t h e s e two  t h e 40$  showed t h a t  component and  the  fractions  lower  the h i g h e r b o i l i n g  component.  the higher b o i l i n g  (complete r e s u l t s  gave a  p u r e and a h i g h e r b o i l i n g  P h o t o l y s i s r e a c t i o n s have been c a r r i e d l o w e r and  using a  s p i n n i n g band s t i l l  the o r i g i n a l mixture p y r a z o l i n e  boiling  distillation  will  fractions,  be d i s c u s s e d  and  later)  o u t on b o t h t h e i t was  that  the  found former  gives mainly cis-1,2-dimethyl-l-carbomethoxycyclopropane and t h e l a t t e r g i v e s m a i n l y  (X)  trans-1,2-dimethyl-l-carbomethoxy-  „ 8 -  [A) Lower b o i l i n g  fraction  'B) P y r a z o l i n e m i x t u r e XX (C) H i g h e r b o i l i n g  (A)  (B)  fraction  XVII  (60$)  XVI  (93$)  (C)  XVII  (99*$) XVI  (4b$)  XVII (7$),  XVI  si" 6.3 {  6:3  r  FIGURE I V - N.m.r. a b s o r p t i o n s s h o w i n g t h e s e p a r a t i o n o f 3 , 5 d i m e t h y l - 3 - c a r b o m e t h o x y - ^ - p y r a z o l i n e (XX) i n t o i t s c i s (XVI) and t r a n s ( X V I I ) i s o m e r s .  - 9 -  cyclopropane  ( X I ) . On t h e b a s i s o f t h e f a c t  that  the photo-  1 lysis  o f A. - p y r a z o l i n s  gives cyclopropane  (12),  the lower b o i l i n g  i s o m e r was a s s i g n e d t h e s t r u c t u r e c i s -  . 3,5"dimethyl-3-carbomethoxy-A* '-pyrazoline  (XVI) a n d t h e h i g h e r  1  boiling  i s o m e r was a s s i g n e d t h e s t r u c t u r e  3~carbomethoxy-£^~pyrazoline tural  assignments  p y r a z o l i n e XVII Steric each  stereospecifIcally  i s based  trans-3,5-dimethyl-  (XVII). Further proof of s t r u c -  on t h e h i g h e r y i e l d  of the trans-  t h a n t h e c i s - p y r a z o l i n e XVI on p r e p a r a t i o n .  h i n d r a n c e due t o t h e  and  other- i n XVI w o u l d slow  methyl  groups  down I t s f o r m a t i o n when compared  t o X V I I . I n o r d e r t o o b t a i n more e v i d e n c e , t h e salt  (XXII)  c i s to  hydrobromide  trans-3,5-dimethyl-3-carbomethoxy-^-pyrazoline  of  ( X V I I ) h a s b e e n p r e p a r e d a n d i s p r e s e n t l y b e i n g a n a l y z e d by the s i n g l e  c r y s t a l X - r a y method. X X I I i s w h i t e  s o l i d with melting point II-2.  at  crystalline  152-153°.  c i s and t r a n s - 3 , 5 - d i m e t h y 1 - 3 - a c e t y l - A " - p y r a z o l i n e 1  (XVIII  and XIX) 3,5-Dimethyl-3-acetyl-A -pyrazoline 1  by t h e a d d i t i o n o f m e t h y l methanol s o l u t i o n  ( X X I I I ) was p r e p a r e d  i s o p r o p e n y l ketone  t o an e t h e r -  of diazoethane. I t i s a c o l o r l e s s  liquid  COCH, H  V  E  /  /  COGH-  fe=C' N  C H  -|-  r  .  3  CH CHN 3  2  "*  3  |C  ether- ^ . methanof  PCEL  ^ E^(f  5  ""3  "N " 5  XXIII which b o i l s  at  56-57°/!.2  mm.  a n d t u r n s y e l l o w i s h on p r o l o n g e d  - 10 -  e x p o s u r e t o a t m o s p h e r e . The n.m.r. s p e c t r u m to and  be a 40°-60 m i x t u r e  o f XXIII  o f t h e two p o s s i b l e g e o m e t r i c  showed i t Isomers  t h e r e was no a b s o r p t i o n o f p r o t o n a t t a c h e d t o a n i t r o g e n  atom. F r a c t i o n a l  distillation  o f XXIII  p r e s s u r e gave a l o w e r  b y s p i n n i n g band  at  reduced  and a h i g h e r b o i l i n g  of  81$ a n d 97$ p u r i t y r e s p e c t i v e l y , and t h e y were f o u n d  t h e 40$ a n d 60$ components o f X X I I I The boiling  results  the  latter  (XXV). T h e r e f o r e  respectively.  isomers  showed t h a t t h e f o r m e r  t r a j o s - 1 , 2-dime t h y 1-1 -a c e t y l c y c l o p r o p a ne  on t h e b a s i s o f s t e r i e  hindrance  formation of 3,5-dimethyl-3-acetyl~£ -pyrazoline L  isomer  to  ( X V I I l ) and t h e h i g h e r b o i l i n g  isomer  analogous t o t h e assignment t o t h e c i s and 3-earbomethoxy-£ -pyrazoline L  n.m.r. d a t a  methoxy-^-pyrazoline  boiling  was  assigned  (XIX) . T h i s i s  trans_-3,5-dlmethyl-  (XVI and X V I I ) .  o f c i s and  trans-3,5-dimethyl-3-carbo-  (XVI a n d X V I I ) a n d c i s a n d t r a n s - 3 , 5 -  dimethyl-3-aeetyl-^"-pyrazoline i n Table I .  ( X X I I I ) and  cis-3,5-dimethyl-3-acetyl-^-  be t r a n s - 3 , 5 - d i m e t h y l - 3 - a e e t y l - ^ - p y r a z o l i n e  The  during the  o f the p h o t o l y s i s r e a c t i o n s , the lower  was a s s i g n e d t o be  pyrazoline  t o be  c i 3 - l , 2 - d i m e t h y l ~ l - a c e t y l c y c l o p r d p a n e (XXIV) a n d  gives mainly  the r e s u l t s  fraction  o f the p h o t o l y s i s r e a c t i o n s o f t h e lower  and t h e h i g h e r b o i l i n g  gives mainly  still  ( X V I I I and XIX) a i t t a b u l a t e d  TABLE N.m.r. d a t a cis Sample  o f c i s and t r a n s - 3 , 5 - d i m e t h y l - 3 - a c e t y l - ^ - p y r a z o l i n e  and trans-3,5-dimethyl-3-carbomethoxy-i£-pyrazollne  A c e t y l methyl E s t e r methyl C^-methyl C^-methyl hydrogens hydrogen hydrogen hydrogens  6.33  XVI  singlet  8.38  singlet  ( X V I I I a n d XIX) a n d  (XVI a n d X V I I )  -hydrogens  8.51  5.42  doublet  sextet  J*7.0  J*7.5  C4-hydros;ens  7.68 J  XVII  6.27  singlet  8.63  singlet  9.14  2. . d o u b l e t s 2 d o u b l e t s Jgem"-^ • 9 J g e n T ^ .8  J  vic~^*5  8.56  5.43  8.28  J=7.0  J«7.5  doublets 2 doublets gerrT '6 ^gem~ 8 vic~ ' vio"" '  doublet  sextet  2  12,  8  8.43  0  „  doublet"  7.78  8.40  singlet  singlet  8.52 doublet  J*7.0  5.66 sextet  J^7.4  7.57  7.65  singlet  1) A V l l l . 2) #) .  8.63  singlet  8.48  5.67  J*6.0  J*7.4  doublet  sextet  J  1 2  J  8  0  8.45  „  doublet^  9.30  2 doublets  2 doublets  Jgem^-'-S.O  Jg —12.8  J  XIX  ^8.o  8.55  J  XVIII  v i c  vie~8*7 8.53  em  J  v l c  -7.7  multiplet  a n d A I A were done on • 205& s o l u t i o n i n 0014, A V I a n d A V I I were done on 3 0 ^ s o l u t i o n i n CCI4, a n d t h e v a l u e s i n p a r e n t h e s e s were o b s e r v e d i n 1 0 $ s o l u t i o n . C h e m i c a l s h i f t i n t' u n i t a n d c o u p l i n g c o n s t a n t i n c . p . s . Due t o t h e s m a l l c h e m i c a l s h i f t s e p a r a t i o n t h e o u t e r d o u b l e t s o f t h e AB s y s t e m were n o t o b s e r v e d ( s e e F i g u r e V ) .  -  12  £OOCH  3  XVII  w  81.56?  ; v l c  8.28*  «8.0"  ! . 8.43 r J«8 .OfM  8.45^ J=*8.0^  Jvic* " ' " 3  30$  8  0  10%  v/v i n CCli|  FIGURE V  v/v  i n CCl^  - N.m.r. s p e c t r a o f t r a n s - 3 , 5 - d i m e t h y l - 3 - c a r b o m e t h o x y - A - p y r a z o l i n e (XVII) showing s p l i t t i n g s of C4-hydrogens. 1  3*  - 13  III.  SEPARATION AND IDENTIFICATION OF PRODUCTS FROM THE DECOMPOSITION OF 3,5~DIMETHYL-3-ACETYL-A*-PYRAZOLINES  Preliminary  studies  (17,26)  on the d e c o m p o s i t i o n o f 3 , 5 -  dimethyl-3-carbomethoxy-A*-pyrazoline trans  (XVII)  i s o m e r s have shown f i v e  ( X X ) , i t s e l s (XVI) a n d p r o d u c t s t o he f o r m e d a s  shown i n F i g u r e V I ( f o r p h o t o l y s i s , a n a d d i t i o n a l was  p r o d u c t XXI  obtained) GOOCH. GOOCH,  XI £OOCH, H  H,  \  S  CH-CC  H.  3  CH  0  2  O  %=c'  ^COOCH,  :  XXVI  XVI  >0H  CH-jCH-  3  g  N^OOCH, XXVII  .COOCH.  H^C  °\3_  W  /  S *  =  H - C - C ^ H . C O O C H  H 3  2  C  C  x  C  0  3  0  C  H  :  CH^  XVII  XXVIII  XXI  FIGURE V I - P r o d u c t s f r o m t h e d e c o m p o s i t i o n o f 3 , 5 - d i methyl-S-carbomethoxy-^-pyrazolines.  In the present study, t h e decomposition o f 3,5-dimethyl3-acetyl-A -pyrazoline  (XXIII),  i t s c i s ( X V I I I ) a n d t r a n s (XIX)  - 14 -  XXV  XXIV  XXV+XXXII  I  XXXII  XXIX  "XXX XIV  LI R e t e n t i o n time d i f f e r e n c e &0.12 min, B  17.7 *  15.7  12.2  Retention  10.5  time i n minutes  6.2 1  A  FIGURE V I I '- A. P r e p a r a t i v e v a p o r c h r o m a t o g r a m s h o w i n g t h e separation of products from the decomposition of 3,5-dImethyl-l-acetyl-Zr-pyrazolines. B. A n a l y t i c a l v a p o r p h a s e c h r o m a t o g r a m s h o w i n g t h e s e p a r a t i o n o f 3-methyl-4-hexen-2-one (XXXII) and t r a n s - l , 2 - d i m e t h y l - l - a c e t y l c y c l o p r o p a n e (XXV)  - 15 -  isomers a f f o r d e d a mixture  of s i x products  as shown by ana-  l y t i c a l vapor phase chromatography ( F i g u r e V I I ) w i t h p o i n t s r a n g i n g from 119°  t o 152°.  These p r o d u c t s  boiling  a r e shown i n  F i g u r e V I I I and have been i d e n t i f i e d as d e s c r i b e d below. P r e COCH, ,COCH, TJOCH,  HO XXIII  XXV £OCH,  JP w  H  f^CH, •N  HC  N  3  XVIII  C=C  /  0'  CH  /  3  CH CH 3  XXIX ^OCH-  CH CH  3 \2  V  HC 3  /  3  OCH  H  XXXI  XIX FIGURE V I I I - P r o d u c t s  COCH  3  XXX CH  c=c  \ 2  ?3 CH CH = CH-CH-COCH H  3  3  XXXII  from the d e c o m p o s i t i o n  o f 3,5-  dimethyl-S-acetyl-A^-pyrazolines. p a r a t i v e vapor phase chromatographic s e p a r a t i o n gave f i v e fractions mixture  i n which t h e second f r a c t i o n was found t o be a (Figure VII) of 1 -acetyl-tra_ns-l,2-dimethylcyelopro-  pane (XXV)  and 3-methyl-4-hexen-2-one (XXXII) i n the r a t i o o f  approximately position.  8 5 1 5 depending on the c o n d i t i o n o f decoms  The s e p a r a t i o n o f t h i s m i x t u r e  be d i s c u s s e d l a t e r . The p y r o l y s i s  o f XXV and XXXII w i l l  p r o d u c t s have been  charac-  - 16 -  terized  on t h e b a s i s o f t h e i r n.m.r. and I n f r a r e d  d a t a a n d e l e m e n t a l m i c r o a n a l y s i s and t h i s  spectral  i s described  2 , 3 * 5 - T r i m e t h y l - £ - d i h y d r o f u r a n (XXIX) h a s b e e n  (27)  to boil  at  118.5°  a t 746 mm.  which  below. reported  agreed with the value,  o 120  , o f t h i s work. I t s i n f r a r e d  spectrum  presence o f carbon-carbon double-bond e t h e r a b s o r p t i o n a t 8.21M  vinyl  indication spectra  absorption at  a n d 9.63 JX ( 2 8 ) .  of absorption i n the Infrared  attributable  5.87M  and  T h e r e was no  o r n.m.r. ( F i g u r e I X )  t o t h e a c e t y l m e t h y l p r o t o n s . N.m.r. a b c e n t e r e d a t 8.43 *t was  s o r p t i o n o f an u n r e s o l v a b l e m u l t l p l e t a t t r i b u t a b l e t o t h e methyl groups were t h r e e g r o u p s  indicated the  attached to C  c e n t e r e d a t 7.98  of multlplet  5.59 Y w h i c h  c a n be a s s i g n e d t o t h e h y d r o g e n s  g e n s ) and C  (one h y d r o g e n ) . T h e s e  and C^.' T h e r e  2  T , 7.40't and  on  (two h y d r o -  three protons c o n s t i t u t e d a  5 typical J B  X  ABX s y s t e m  — 9.5  1Q9  c.p.s.,  (29)  w i t h J «*tl4.5 c.p.s., J AB  A^-^35.5  c.p.s., A .  ^l44.5  c.p.s. I n order t o e s t a b l i s h the c y c l i c  2,3j5-trimethyl-A-dihydrofuran a similar III)  A X  (30)  cyclic  c.p.s.,  c . p . s . and A g  X  ^  structure of this  compound, t h e 2 - m e t h y l - A ? - d i h y d r o f u r a n (XXX-  was o b t a i n e d f o r c o m p a r i s o n . The n.m.r. s p e c t r u m o f  showed a b s o r p t i o n a t 8.30 f  plet),  7.47  TT* ( m u l t l p l e t ) a n d 5.78  s.) a t t r i b u t a b l e t o C and G^ h y d r o g e n s  2  (multiplet), (triplet  methyl hydrogens,  r e s p e c t i v e l y . A comparison  o f XXIX a n d X X X I I I  similarly  e>8.0  ( X X I X ) , t h e n.m.r. s p e c t r u m o f  XXXIII  spectra  A X  situated  5.55  X  (multl-  w i t h Jc=t9.3 c . p .  v i n y l hydrogen,  G^  o f t h e n.m.r.  showed good c o r r e l a t i o n  between  protons, conforming the s t r u c t u r a l  assign-  - 17 -  FIGURE I X  - N.m.r. s p e c t r u m o f 2 , 3 , 5 - t r i m e t h y l - f c furan  (XXIX)  dihydro-  - 18 -  ment o f - 2 , 3 , 5 - t r i m e t h y l - & - d i h y d r o f u r a n cis-3-Methyl-3-hexen-2-one hexen-2~one  reported  its  boiling  156.5-158°  bond  point  i n f r a r e d bands  a t 6.-18  It i s possible  a m i x t u r e o f t h e two  and XXXI. The  ( s i n g l e t ) and 7.81 at  8.12  X  geometry  M  and 5 . 9 1  p o s s i b l e geometric  Jd r e s p e c t i v e l y ,  and a t 6.07  M  and 5.96  JX r e -  ( X X X I ) . The  ( s i n g l e t ) due t o a c e t y l m e t h y l  and a t 4.44  Y  (multiplet)  due  'i ( m u l t i p l e t ) and  to  3.52  "t  hydrogens, vinyl •f ( m u l t i -  t o v i n y l h y d r o g e n s , r e s p e c t i v e l y . The a s s i g n m e n t t o c i s and t r a n s - 3 - m e t h y l - 3 - h e x e n - 2 « o n e vinyl  (XXX and XXXI)  1\  I n XXXI t h e  hydrogen  i s c i s t o t h e a c e t y l g r o u p , whereas i n XXX,  hydrogen  I s t r a n s t o t h e a c e t y l g r o u p . I n o t h e r words,  v i n y l h y d r o g e n i n XXXI I s c l o s e r  i n a c e t y l group would  XXXI t o a g r e a t e r e x t e n t  vinyl  the  vinyl  the  t o the a c e t y l group than i n  t h e r e f o r e the diamagnetic a n i s o t r o p y of the  double-bond  of  proton a b s o r p t i o n of the  l a t t e r a t 3 . 5 2 f t h a n t h e f o r m e r a t 4.44  in  by  f o r the c i s -  and XXXI showed a b s o r p t i o n a t 7.86  were b a s e d on t h e l o w e r f i e l d  XXX,  gave  c a r b o n y l f u n c t i o n were i n d i c a t e d  ( m u l t i p l e t ) and 8.39  methyl hydrogens p l e t ) due  H  and  t h a t t h e i r o^fi-  f o r the trans-3-methyl-3-hexen-2-one o f XXX  Shoule  presence of carbon-carbon double-  3 - m e t h y l - 3 - h e x e n - 2 - o n e . (XXX)  n.m.r. s p e c t r a  points at  o f 3-tnethyl-3~hexen-2-one  v a l u e , 151°•  and o^fi-unsaturated  spectively,  trans-3-methyl-3-  r e s p e c t i v e l y . Rohrmann and  the s y n t h e s i s  u n s a t u r a t e d k e t o n e was I s o m e r s XXX  and  (XXXI) have b e e n f o u n d t o have b o i l i n g  1 4 5 - 1 4 5 . 5 ° and (31)  (XXX)  (XXIX) .  deshield  carbon-oxygen  the v i n y l proton  to give a lower f i e l d  absorption  - 19 -  (32).  This shift  i n t h e v i n y l hydrogen  i n many o t h e r c i s a n d t r a n s p a i r s  r e g i o n has been (38).  of olefins  1-Acetyl-c is-1,2-dimet.hylcyclopropane acetyl-trans-l,2-dimethylcyclopropane  (XXV) showed no  * but carbonyl conjugated t o the cyclopropane r i n g  at  1-  (XXIV) a n d  r e d a b s o r p t i o n bands a t t r i b u t a b l e t o c a r b o n - c a r b o n  f o r XXIV a n d 5.96 A  observed  f o r XXV > a n d i n a d d i t i o n ,  infra-  double-bond  (33)  at  5.90>*  t h e r e was a b a n d  9.76 M f o r XXV due t o a b s o r p t i o n o f c y c l o p r o p a n e r i n g  (3^0 .  T h e i r n.m.r. s p e c t r a showed no s i g n a l due t o p r o t o n a t t a c h e d to the carbon-carbon characteristic ton at  double-bond  of cyclopropane r i n g  a b s o r p t i o n s appeared 8.68 f  but high f i e l d absorption p r o t o n s . These r i n g  a s two g r o u p s  (two h y d r o g e n s ) and 9.7^  of signals; . c e n t e r e d  1* (one h y d r o g e n ) i n t h e  case o f l - a o e t y l - c i s - l , 2 - d i m e t h y l c y c l o p r o p a n e t h e r e g i o n o f 8.75 '£ t o 9.06 TT i n t h e e a s e 7  1,2-dimethylcyclopropane obscured  o f 1-acetyl-trans_-  t o those o f t h e analogous  of their  n.m.r.  carbomethoxy-cyclopropanes,  namely l - c a r b o m e t h o x y - c l s _ - l , 2 - d i m e t h y l c y c l o p r o p a n e carbomethoxy-trans-l,2-dlmethylcyclopropane c h e m i s t r y has a l r e a d y been determined (12)  on t h e b a s i s  than that  of XI.  (X) a n d  1-  ( X I ) whose s t e r e o -  b y v a n Auken and R i n e h a r t  of competitive saponifications  l e s s h i n d e r e d carbomethoxy group  partly  g r o u p s . The s t e r e o c h e m i s t r y  o f XXIV a n d XXV were made b y c o m p a r i s o n spectra  (XXIV) and i n  (XXV). T h e s e m u l t i p l e t s were  by a b s o r p t i o n o f methyl  pro-  i n which t h e  o f X was consumed more  rapidly  - 20 -  3-Methyl-4-hexen-2-one  (XXXII) was  eluted  a t t h e same  t i m e as 1 - a c e t y l - t r a n s - 1 , 2 - d i m e t h y l c y c l o p r o p a n e  (XXV) f r o m t h e  p r e p a r a t i v e v a p o r phase chromatography column. Attempts t o separate t h i s  ^^-unsaturated  packed w i t h v a r i o u s tion  k e t o n e XXXII b y u s i n g  s u b s t a n c e s were n o t s u c c e s s f u l . B r o m i n a -  of the mixture c o n s i s t i n g  3-methyl-4~hexen-2-one  and 1 - a c e t y l - t r a j i s - 1 , 2 - d i m e t h y l c y e l o p r o p a n e tetrachloride instead tive  gave XXV  before  stable  i n carbon  i n the prepara-  3-methyl-4-hexen-2-one  a t t h e t e m p e r a t u r e o f t h e column, t h e c o n -  o f X X X I I o r i t s d i b r o m i d e t o XXXI must h a v e i t was  hexen-2-one indicated  injected  i n t o the column. Although  (XXXII) was  not I s o l a t e d  pure, I t s presence  *f  ^6.94  attrib-  to d i s -  (multiplet)  CH CH^H-CH-COCH ^ 3  not p o s s i b l e  was  1-acetyl-  (XXV). Those a b s o r p t i o n s  u t a b l e t o XXXII a r e shown b e l o w . I t was (multiplet)  occurred  3-methyl-4-  i n t h e n.m.r. s p e c t r u m o f t h e m i x t u r e w i t h  trans-l,2-dimethylcyclopropane  4.57 i  (XXXII)  a n d t r a n s - 3 - m e t h y l - 3 - h e x e n - 2 - o n e (XXXI)  v a p o r phase chromatogram. S i n c e  version  (XXV)  o f t h e d i b r o m i d e o f XXXII a s i n d i c a t e d  (XXXII) was  columns  3  7.97 Y  8.32 r 3""*"—-—8.92 Y ( d o u b l e t , J ~ 4 . 8 c.p.s.)  (singlet)  ( d o u b l e t , Jc^7.0 c.p.s.)  XXXII t i n g u i s h whether the v i n y l  hydrogens i n the molecule are c i s  or t r a n s t o each o t h e r . Elemental m i c r o a n a l y s i s containing  3-methyl-4-hexen-2-one  1,2-dimethylcyclopropane pirical  formula  C H  (XXV) was  ( X X X I I ) and  of the mixture  1-acetyl-trans_-  i n good agreement t o t h e  0, w h i c h i s common t o b o t h XXV  em-  and X X X I I .  - 21 -  I V . DECOMPOSITION OF  3,3,5-TRISUBSTITUTED  A -PYRAZOLINES 1  Preliminary pyrolysis  1  (XVI and X V I I )  )> n a m e l y , c i s and  cyclopropane pentenoate (XXVIII)I late  affords  five  products  (X and X I ) , m e t h y l  2-methyl-3-pentenoate  (XXIII),  and  found to g i v e  cis  and  s i x products  trimethyl-A -dlhydrofuran  Photolysis  and XXXI) and  report1  trans  (Figure VIII, (XXIV  ( X X I X ) , c i s and  2  (XXX  methacry-  3,5-dimethyl-3-acetyl-A -  i t s c i s ( X V I I I ) and  trans-1,2-dimethylcyclopropane  hexen-2-one  peak, m e t h y l  f o u n d . S i m i l a r p y r o l y s i s r e a c t i o n s , as  ed i n t h i s work, were c a r r i e d o u t on pyrazoline  VI,  trans-2-methyl-2-  c i s and  on p h o t o l y s i s , an a d d i t i o n a l was  (Figure  trans-1,2-dlmethyl-l-carbomethoxy-  (XXVI and XXVII) and m e t h y l  (XXI),  the  trans-3,5-dimethyl-3-carbomethoxy-A -  o f c i s and  pyrazoline p. 13  i n v e s t i g a t i o n s have -keen, shown t h a t  (XIX)  isomers  p . 15)° and  1-acetyl-  2,3,5-  XXV),  trans-3-methyl-3-  3-methyl-4-hexen-2-one  of these a c e t y l - p y r a z o l i n e s  gave no a d d i t i o n a l p r o d u c t . T h e s e  (XXIII,  (XXXII).  X V I I I and  r e s u l t s are tabulated  XIX) in  T a b l e s I I and I I I .  It  c a n be  seen t h a t  the decomposition reactions  dimethyl-3-acetyl-A^"-pyrazoline trans  (XIX)  isomers give  (XXIII),  r e s u l t s that  dimethyl-3-carbomethoxy-A -pyrazoline 1  trans  (XVII)  isomers  ratio  of o l e f i n s  of  i t s c i s (XVIII)  resemble  those of  ( X X ) , i t s c i s (XVI)  r e s p e c t i v e l y . P y r o l y s i s gave  3,5and 3,5and  higher  to eyclopropanes than d i d p h o t o l y s i s . In the  TABLE I I Product  compositions f o r the decomposition of 3>5-dimethyl-3-acetyl-A  Sample  Reaction  Cyclopropane  conditions  cis  trans  XXIV  XXV  Unsaturated  -pyrazolines  ketone  Dihydrof uran  cis-«k/S t r a n s - o ^ XXX  XXXI  XXXII  XXIX  (cis)  V a p o r phase p y r o l y s i s  at  125°  27  48  : 7  3  2  13  (trans)  V a p o r phase p y r o l y s i s  at  125°  67  19  2  7  2  3  XXIII  (mixt.)  Liquid  phase p y r o l y s i s ,  100°  36  18  15  18  4  9  XVIII  (cis)  Liquid  phase p y r o l y s i s ,  100°  22  25  27  2  10  14  (trans)  Liquid  phase p y r o l y s i s ,  100°  62  17  1  17  3  0  XXIII  (mixt.)  Thermal p y r o l y s i s  at  250°  48  32  5  3  3  9  XVIII  (cis)  Thermal p y r o l y s i s  at  250°  28  41  12  1  2  16  (trans)  Thermal p y r o l y s i s  at  250°  60  27  1  6  3  .3  XXIII  (mixt.)  Photolysis  i n ether at  35°  39  4  4  6  3  6  XVIII  (cis)  Photolysis  i n ether at  35°  59  28  .1  0  6  6  (trans)  Photolysis  i n ether at  35°  21  70  2  1  4  2  XVIII XIX  XIX  XIX  XIX  2  ,  TABLE I I I Product  compositions f o r the decomposition of  3,5-dimethyl-3-carbomethoxy-& -pyrazolines L  Cyclopropane Sample  XX XVI XVII XX XVI XVII XVI XVII  Reaction  conditions  cis  trans  Unsaturated ester cis-0^2.  t r a n s - <*$ XXVII  X  XI  XXVI  p»i  Methyl methacrylate  XXVIII  XXI  (mixt.)  V a p o r phase  pyrolysis  (17)  53  42  3  2  1  0  (cis)  V a p o r phase  pyrolysis  (17)  23  65  • 5  2  5  0  (trans)  V a p o r phase  pyrolysis  (17).  76  15  1  3  5  0  (mixt.)  Liquid  phase  pyrolysis  (17)  45  27  10  15  3  0  (cis)  Liquid  phase  pyrolysis  (17)  18  48  32  0  2  0  (trans)  Liquid  phase  pyrolysis  (17)  60  15  0  22  3  0  (cis)  Photolysis  i n ether at  35°  6l  23  6  2  2  6  (trans)  Photolysis  i n ether at  35°  22  65  0  5  2  6  _ 24  olefin  of the products, c i s - 3 , 5 - d i m e t h y l - A - p y r a z o l i n e s  fraction  gave p r e d o m i n a n t l y ^-pyrazolines  -  t h e oG^-c i s - o l e f i n s  gave p r e d o m i n a n t l y  cyclopropane f r a c t i o n  and  tra_ns_-3,5-dimethyl-  the o ( , ^ - t r a n s - o l e f i n s . In  o f t h e p r o d u c t s , c i s and  m e t h y l - A ^ - p y r a z o l i n e s gave more t r a n s and  trans-3,5-di-  cis-l,2-dimethyl-  c y c l o p r o p a n e r e s p e c t i v e l y , whereas on p h o t o l y s i s , reversed  only s i g n i f i c a n t  e s t e r p y r a z o l i n e s was  d i f f e r e n c e between the k e t o  from the decomposition  lines.  I t i s noteworthy  that  of the keto p y r a z o l i n e s ,  pyrazoline On  and  t h e d i h y d r o f u r a n p r o d u c t XXIX w h i c h  formed  r e a c t i o n s of the keto this  p r o d u c t was  formed  was  pyrazofrom  only  cis-3,5-dimethyl-3-acety.l-A 1  (XVIII), i n s i g n i f i c a n t  amount.  the b a s i s of the p o s t u l a t e d p o l a r Intermediate In the  pyrolysis solvent  t h e y were i n  abundance.  The  one  the  reaction  might  i t Is a n t i c i p a t e d  i n f l u e n c e the product  a c t i o n , hence p y r o l y s i s  ratio  the p o l a r i t y and  f o r cyclohexane  o u t on t h e c i s and  3-carbomethoxy-A^-pyrazoline  (XVI and  of  the  the r a t e of r e -  i n a number o f s o l v e n t s w i t h  c o n s t a n t s v a r y i n g f r o m 2D amide h a v e b e e n c a r r i e d  that  t o 109D  dielectric  f o r form-  trans_-3,5-dimethyl-  X V I I ) . Samples o f 0.2  ml.  o f t h e e s t e r p y r a z o l i n e i n 20 m l . o f s o l v e n t i n a s e a l e d t u b e were h e a t e d  for  t h e s o l v e n t was  90  a t . 1 2 5 ° . F o r low b o i l i n g  removed by d i s t i l l a t i o n  Column u n d e r r e f l u x was  minutes  c o n d i t i o n , and  a n a l y s e d by a n a l y t i c a l v a p o r  solvents,  t h r o u g h a s p i n n i n g band  the concentrated  solution  phase c h r o m a t o g r a p h y . F o r  - 25 -  f o r m a m i d e , t h e p r o d u c t s were r e c o v e r e d vacutam l i n e by pumping  of the solvent  a m i d e , up t o 57$ cyclohexane, only  i n f l u e n c e of the  on t h e p r o d u c t  of the product 7$  constants  was  of the product  P h o t o l y s i s o f c i s and lt-pyrazoline  was  effect  i n f o r m a m i d e , up t o 21$ i n cyclohexane,  In form-  olefins.  trans-3j>5~dlmethyl-3-carbomethoxy-  showed a s i m i l a r s o l v e n t  f i n s whereas  dielectric  composition.  (XVI and X V I I ) i n s o l v e n t s  example,  IV)  o l e f i n s , whereas i n  p o s i t i o n as i n t h e p y r o l y s i s r e a c t i o n s for  on a  f o r two h o u r s . T h e s e r e s u l t s ( T a b l e  showed a s m a l l and r e g u l a r constant  from the solvent  i t was  of varying  dielectric  on t h e p r o d u c t  com-  but In l e s s e r degree"  of the product  was  ole-  5$.  The ^.kinetic  effect  has b e e n examined f o r t h e  of 3,5-dImethyl-3-carbomethoxy-fif'-pyrazoline  pyrolysis various  solvent  solvents  decreased  and i t was  i n the order  found that  within  a f a c t o r of three Liquid  the rate of p y r o l y s i s  of di-n-butyl ether,  b e n z e n e and f o r m a m i d e . The r a t e s  1  i n these solvents  nitro-  were a l l  ( F i g u r e s X I I -and—3EEB).  ( X V I I ) has been c a r r i e d o u t i n s o l v e n t s  s u c h as 2 , 3 - d i m e t h y l b u t a n e and d i e t h y l e t h e r  the  tetralin,  phase p h o t o l y s i s o f t r a n s - 3 , 5 - d i m e t h y l - 3 - c a r b o -  methoxy-A -pyrazoline  peratures  (XX) i n  ranging  f r o m -55°  temperature e f f e c t  t o 58°  at various  tem-  i n an a t t e m p t t o d e t e r m i n e  on p h o t o l y s i s o f ^ - p y r a z o l i n e s .  Pro-  d u c t a n a l y s i s b y a n a l y t i c a l v a p o r p h a s e c h r o m a t o g r a p h y showed no a p p r e c i a b l e  change a t t r i b u t a b l e t o t h e i n f l u e n c e o f tern-  TABLE I V Product  compositions  f o r the sealed-tube p y r o l y s i s  dimethyl-3-carbomethoxy-^-pyrazoline 1  o f c i s and  i n various solvents  trans-3,5-  at 1 2 5 °  =  Cyclopropane Solvent  Sample  cis X  #  trans  Unsaturated cis-fl^  XI  XXVI  ester  t r a n s - s ^» XXVII  fr& XXVIII  2 . 0 7  D  2 5  6 2  1 2  0  1  Cyelohexane  2 . 0 7  D  3 0  5 5  1 1  3  1  (cis)  Ethyl  4 . 3 4  D  2 5  5 6  1 6  2  1  XVI  (cis)  Methanol  3 3 . 6  D  2 1  3 9  3 4  4  2  XVI  (cis)  Acetonitrile  3 7 . 5  D  2 1  42  3 1  4  2  XVI  (cis)  Formamide  D  1 9  3 3  4 4  2  2 "  D  7 0  2 3  1  5  1  XVI  (cis)  XVI  (cis)  XVI  Cyclohexane  ether  1 0 9  #  XVII  (trans)  XVII  (trans)  Cyclohexane  2 . 0 7  D  7 2  2 0  0  6  2  XVII  (trans)  Ethyl  4 . 3 4  D  6 6  1 8  0  1 3  3  XVII  (trans)  Methanol  3 3 . 6  D  48  6  0  4 4  2  XVII  (trans)  Acetonitrile  3 7 . 5  D  6 7  6  0  2 5  2  XVII  (trans)  Formamide  D  3 1  1 2  0  5 2  5  # a t 81°,  Cyclohexane ^ 77  ether  not i n sealed-tube.  2 . 0 7  1 0 9  :  TABLE V Product compositions  o f p h o t o l y s i s o f c i s and  trans-3,5-di-  methyl-3-carbomethoxy-^"-pyrazoline Cyclopropane Solvent  Sample  and  temperature  cis  trans  Unsaturated e s t e r els-^p  trans-atyS  XXVI  XXVII  Methyl ^  methacry-  late  X  XI  XXVIII  XXI  58°  28  ' 63  3  4  2  0  35°  22  65  0  5  2  6  XVII ( t r a n s )  2,3-Dimethyl butane  XVII ( t r a n s )  Ethyl  ether  XVII ( t r a n s )  Ethyl  ether  0°  27  56  1  7  3  6  XVII ( t r a n s )  Ethyl  ether  -20°  25  55  1  8  3  8  XVII ( t r a n s )  Ethyl  ether  -55°  25  53  1  10  4  7  Cyclohexane^  81°  43  45  7  0  1  4  Cyclohexane^  81°  46  45  0  4  1  4  Formamide  23°  54  21  9  5  1  .10  Formamide  23°  15  58  2  16  3  6  XVI ( c i s ) XVII ( t r a n s ) XVI ( c i s ) XVII ( t r a n s ) # at  81,  py r o l y s i s a l s o  (26)  occurred at  a r a t e three times  s l o w e r t h a n -pyrolyoirj-.  - 28 -  p e r a t u r e . These  results  a r e shown i n T a b l e V.  P h o t o l y s i s and p y r o l y s i s f o r e they- might  well  gave t h e same p r o d u c t s , t h e r e -  i n v o l v e t h e same i n t e r m e d i a t e . I n o r d e r  t o d e t e r m i n e w h e t h e r t h e p r o d u c t c o m p o s i t i o n was d e p e n d e n t temperature pyrolysis  o r on t h e n a t u r e o f t h e r e a c t i o n ,  o f c i s and  pyrazoline  on  p h o t o l y s i s and  trans-S^-dimethyl-S-carbomethoxy-A 1  (XVI and X V I I )  were c a r r i e d  o u t a t t h e same tem-  p e r a t u r e , 8 l ° , w i t h c y c l o h e x a n e as s o l v e n t . I t was f o u n d t h e e v o l u t i o n o f n i t r o g e n t o be t h r e e t o f o u r t i m e s f a s t e r by photolysis  t h a n b y p y r o l y s i s . The p r o d u c t c o m p o s i t i o n s  t h e s e two r e a c t i o n s were n o t t h e same d e s p i t e t h e y were r u n u n d e r these conditions yielded try  identical  indicate  c o n d i t i o n s . The r e s u l t s  as i n o t h e r s y s t e m s \ greater -  eyclopropanes w i t h h i g h degree  of the s t a r t i n g  was a l s o  pyrazoline  found t h a t  the r a t i o  the f a c t  that  of retention  from that under  photolysis o f geome-  than those from p y r o l y s i s . I t of olefins  to eyclopropanes  t h e s e r e a c t i o n s was l o w e r f o r t h e p h o t o l y s i s  from  than the  pyrolysis. A further test b a s e d on t h e f a c t  of the e a r l i e r  that  p r o p o s e d mechanism was  t h e r e s h o u l d be r o t a t i o n o f t h e C^-Cjj  bond i n t h e d i a z o n i u m h f t t a i n e i n t e r m e d i a t e XXXIV and t h a t i t would form 3 , 5 - d i m e t h y l - 3 - c a r b o m e t h o x y - A ^ - p y r a z o l i n e cyclization pyrolysis  faster  of  than l o s s  of nitrogen. Liquid  (XX) b y  phase  trans-3,5-dimethyl-3-carbomethoxy-.A -pyrazoline  ( X V I I ) a t 90° was c a r r i e d  1  t  t o 50$ c o m p l e t i o n , and t h e r e c o v e r e d  u n r e a c t e d p y r a z o l i n e was a n a l y s e d b y n.m.r.' I t was f o u n d  that  - 29 -  COOCH-  3  fc„, • N  3  H C* N^  **"*  r<  COOCH  ~ \ Q  /\  H 3  3  _ J J• —***•  H C  N  3  eyclopropanes and o l e f i n s  3  XX  not  /  XXXIV  more t h a n 1% i s o m e r i z a t i o n o f X V I I t o c i s - 3 , 5 - d i m e t h y l - 3 A"  carbomethoxy-A- -pyrazoline L  was  o b s e r v e d when  pyrazoline  35°.  (XVI) h a d o c c u r r e d , (^similar  result  tr£ns_-3,5-dimethyl-3-carbomethoxy-A -  (XVII) i n d i e t h y l  1  e t h e r was p a r t i a l l y  photolysed at  - 30 -  V . DISCUSSION  The  thermal p y r o l y s i s  carbomethoxy-A -pyrazollne  (VI and V I I ) has been r e p o r t e d by  1  Rinehart  a n d v a n Auken  trans_-3,4-dimethyl-3-  o f c i s and  (12)  to proceed with r a c e m i z a t i o n at  C^ t o g i v e c y c l o p r o p a n e p r o d u c t s i n w h i c h and  trans with that  present  cyclopropane which  retains  i n the pyrazoline being s l i g h t l y  example, t h e c i s - p y r a z o l i n e V I g i v e s bomethoxycyclopropane methoxycyclopropane  (X) a n d  t h e methyls  are c i s  t h e geometry  predominant. F o r  cis-l,2-dimethyl-l-car-  trans-1,2-dimethyl-1-carbo-  (XI) i n t h e r a t i o  1.00*0.70  of  whereas  the t r a n s - p y r a z o 1 i n e V I I g i v e s X and XI i n t h e r a t i o o f  1.00*1.22.  R i n e h a r t a n d v a n Auken s u g g e s t e d t h a t  rotation  COOCH,  3  VI  H Q  „C00CH  A.  ^OOCH^  3  H  3  C _  ~r*0H  :  about VIII  o  £00CH  H 0. o  *\/N"IL  \/ ^ 3  X  XI  V I I  t h e O^-C^ bond i n t h e d l a z o n i u m b s f c a i n e i n t e r m e d i a t e accounts  f o r the l o s s o f geometric  integrity  £00CH<  H C 3  ^  H Ng  3  VIII  and t h a t  o  - 31  the loss of n i t r o g e n Is only s l i g h t l y give a higher y i e l d  of the cyclopropane which r e t a i n s  ometry p r e s e n t I n the  o f c i s and  pyrazoline acetyl-A  (XVI and  methyls  found t h a t  the  thermal 1  trans-3,5-dimethyl-3-  X V I I ) , c i s and  a l s o proceeds  to give cyclopropane  a r e c i s and  t r a n s but  the cyclopropane w i t h  d o m i n a n t . F o r example, t h e r a t i o methyl-l-acetylcyclopropane o f X V I I I and XIX ^£OCH  with  products i n which  s i o n o f t h e g e o m e t r y p r e s e n t i n t h e p y r a z o l i n e was  pyrolysis  ge-  trans-3,5-dlmethyl-3-carbometho3cy-A -  - p y r a z o l i n e ( X V I I I and XIX)  racemization at  the  to  pyrazoline.  I n t h e p r e s e n t work, i t was pyrolysis  slower than r o t a t i o n  were  22*25  and  inverfound  pre-  trans-l,2-di-  o f c i s and  (XXIV and XXV)  the  from the  62*17  thermal  respectively.  3  n/V  XIX  A second  important  f e a t u r e o f t h e p r e s e n t work i s t h a t  the formation of o l e f i n s  from the p y r o l y s i s  A -pyrazolines- i s highly  stereospecif i c .  1  trans-3-methyl-3-hexen-2-one  (XXX  and  The  of  3*5-dimethyl-  ratio  o f c i s and  XXXI) f r o m t h e  pyrolysis  32 -  c i s and t r a n s - 3 , 5 - d i m e t h y l - 3 - a c e t y l - / ^ - p y r a z o l i n e  of and  XIX) were  ficity  27»2  and 1*17 r e s p e c t i v e l y . T h i s  has not b e e n  observed p r e v i o u s l y  COCH,  H  ^  CH CH  3  H. XVIII  c=c N  2  since an  CH  CH CH  3  3  3\2 / .c=cf  ^ H  2  H  3  /  X  CH  C  o f o l e f i n s has  p r e v i o u s l y b e e n t h o u g h t t o be f o r m e d t h r o u g h t h e  CH, H C 3  C=C  3  2 XXXIV  CH-,  3  CH CH_.  COGCH  H  2  intermediate  3\2  0  / \  \  /  CH CH  /  COCH,  (Ifo)  XXX  m o d e l h a s n o t b e e n a v a i l a b l e . The f o r m a t i o n  \  \  2  XXXI (17$)  H  COCH,  H  3 3  COGCH,  3  XXXI (2%)  CH CH  XIX  appropriate  c=c  COCH  CH CH  A  stereospeci-  (27fo)  XXX £OGrL  /  (XVIII  3  XXVI  CH  3  0  COOCH,  XXVII  XXXIV or XXXV i n w h i c h r o t a t i o n a r o u n d t h e s i n g l e bonds w o u l d give  a m i x t u r e o f c i s and t r a n s  o l e f i n s . For the dlazonium'  bjafcalne XXXIV t o g i v e  such s t e r i c  that  must r e t a i n i t s asymmetry. T h i s  the anion center  anticipated  on t h e b a s i s  c o n t r o l i t would  of studies  require Is not  by Cram and c o w o r k e r s  (39). I n t h e p y r o l y s i s and p h o t o l y s i s  of 3 ,5-dimethyl-3J  - 33 -  acetyl-A -pyrazoline  ( X X I I I ) , i t s c i s ( X V I I I ) and  1  isomers,  an a d d i t i o n a l  (XXIX) was bctaine  (XIX)  2,3,5~trimethyl-A -dihydrofuran  product  2  o b t a i n e d . T h i s c a n be  formed through  i n t e r m e d i a t e (XXXV) w h i c h has  XXXVI. A g a i n  trans  f r e e r o t a t i o n around  the  a. r e s o n a n c e  C^-C^  diazonium  form  bond p r e d i c t s  of that  ,COCH  XXXV cis XIX)  and  XXXVI  XXIX  trans-3,5-dimethyl-3-acetyl~A  - p y r a z o l i n e (XVIII  and  w o u l d g i v e t h e same i n t e r m e d i a t e XXXVI on p y r o l y s i s ,  and  h e n c e t h e y s h o u l d g i v e t h e same amount o f d i h y d r o f u r a n XXIX. Experimental tained  from  results,  however, showed t h e amount o f XXIX  t h e i s o m e r i c p y r a z o l i n e s were s i g n i f i c a n t l y  f e r e n t . F o r example, t h e r m a l  pyrolysis  dimethyl-3-acetyl-A "-pyrazoline 1  j e c t o r of the vapor and  3$,  pyrolysis  of neat  o f t h e d i h y d r o f u r a n was  liquid  s a m p l e s gave 14$  seem t o i n d i c a t e predetermined  by  t h a t the the  s t r u c t u r e of the p y r a z o l i n e s . In f a c t , the s t e r i c of  and  methyl  gave  16$  of 2 , 3 , 5 - t r i m e t h y l - A -dihydrofuran  r e s p e c t i v e l y . These r e s u l t s tion  at the i n -  phase chromatography i n s t r u m e n t  respectively,  ( X X I X ) , and  XIX)  dif-  trans-3,5-  o f c i s and  ( X V I I I and  ob-  and  0%  forma-  molecular interaction  groups i n c i s - S ^ - d i m e t h y l - S - a c e t y l - A 1  pyrazoline  ( X V I I I ) m i g h t be  expected  to f o r c e the  acetyl  group i n t o  a favorable position f o r dihydrofuran formation.  - 34 -  It  i s a n t i c i p a t e d that  dlazonium bataine  the  intermediate  formation  like  I I from  ( I I I ) would cause the  k i n e t i c s of the  er rate  solvents,  i n more p o l a r  o f an  ionic  A^-pyrazolines  r e a c t i o n to  s i n c e the  show a  process  high-  involves  the  R2  3>  Y  Y= -COCH3,  -COOCHo  -N  2 II formation other  of  ionic  woYds, t h e  faster  rate of  i n a solvent  p o l a r i t y . The pyrolysis gen  charges from a n e u t r a l  n-butyl  p y r o l y s i s of A^-pyrazolines  of high  present  o f A ^ - p y r a z o l i n e s , as  ether  than i n p o l a r  n i t r o b e n z e n e o r f o r m a m i d e by opposite  the al  1  p y r o l y s i s of  small  polar  not  small  character  Therefore,  solvents  suggests the  Involve  ionic  of  as  three.  This in  starting material, that  the  therm-  ionic  mecha-  transition state.  o f p y r o l y s i s i n p o l a r and mechanism o f t h e  character.  of  nitro-  intermediate  likely  the  low  rate  such  p r o c e e d s t h r o u g h an  either free radical  large  the  be  s u c h as d i -  solvents,  than the  d l a z o n i u m b u t a i n e I I as  t o be  rate  f a c t o r of  i t i s not  A^-pyrazolines  difference i n rate  pyrazollnes do  less Ionic  A -Pyrazoline.  nism w i t h the The  the  k i n e t i c e f f e c t indicates that  p y r o l y s i s has  the  f a s t e r i n non-polar solvents,  or t e t r a l i n  of  work showed t h e  i n d i c a t e d by  In  should  p o l a r i t y than a solvent  r e s u l t s of the  e v o l u t i o n , t o be  (37).  species  non-  p y r o l y s i s of  or molecular  since  A 1  these  - 35 -  One ionic  f u r t h e r argument c a n  be  made a g a i n s t  mechanisms f o r t h e r m a l p y r o l y s i s . T h i s  predict  that  the  diazonium betaine  XXXIV, w o u l d f o r m p y r a z o l i n e by l o s s of n i t r o g e n .  Since  the  the  mechanism w o u l d  intermediate,  ring  product  proposed  closure  f o r example  f a s t e r than  the  analysis predicts rotation'  COOCH-  N?H  3  HC  N  3  2  XXXIV a b o u t Cg-G^  bond, one  w o u l d a n t i c i p a t e t h a t when  dimethyl-3-carbomethoxy-^"-pyrazoline pyrolysed, cis  the  isomer XVI.  o r i n the lysis  recovered This  work o f van  has  (XVII) i s  sample s h o u l d not  partially  show b o t h X V I I and  been found to occur  Auken and  trans-3,5-  RInehart  (12).  in this  Partial  Its work  photo-  o f X V I I a l s o gave a s i m i l a r r e s u l t .  The  possibility  intermediate  f o r the  of the  diazonium bntaine  I I as  p y r o l y s i s of ^ - p y r a z o l i n e s  is  the therefore  eliminated. R.  ^R  1  2  y  Y =  R  -COCH , 3  -COOCHo  H "  " N  2  II  R e c e n t work I n t h i s  laboratory  (4o)  has  discovered  a  CMT€-  pyrazoline  system which g i v e s  k i n e t i c s that i s  -  s e n s i t i v e to  - 36 -  solvent  p o l a r i t y as e x p e c t e d  O  I n t e r m e d i a t e . The  COOCH,  K  |  |  \  /—* N  C N  ^  N  —  XXXVII  7  C00CH  W  other  o  minor  4.  3  CN  products.  XXXVIII  A - p y r a z o l i n e XXXVII I n t h i s 1  groups  f o r an i o n i c  which  can s t a b i l i z e d  c a s e has  two  electron  withdrawing  a dlazonium b ^ t a i n e intermediate  to a g r e a t e r degree. It fit  i s apparent  a spectrum  around  pyrolysis  of conditions  the azo group  taneously  that  iri which  symmetric  might  substitution  l e a d s t o b r e a k i n g o f b o t h bonds s i m u l -  i n the t r a n s i t i o n  /^-pyrazolines  of ^"-pyrazolines  s t a t e . In h i g h l y  l i k e XXXVII one  unsymmetrical  bond b r e a k s b e f o r e t h e o t h e r .  S u c h a s i t u a t i o n has b e e n shown t o be t h e c a s e f o r l i n e a r compounds  (4l)  H C Q  3 \  where compounds XXXIX, X L , a n d , X L I  /  CH-  C H - N = N - C H  0  HoC  3 v  3  0  /  ,CHo  C H - N = N - C H  0  C H  XXXIX  H  3  XL  initial  o b t a i n e d by It  i s apparent  on t h e  i n the p y r o l y s i s  3,5-dimethyl-3-carbomethoxy-A -pyi azolIne 1  J ! H - N = N - C H ,  breaking of both  bond. These  deuterium e f f e c t s that  C  3 \  XLI  b r e a k i n g o f one  secondary  (0=--C^B.^)  0  3  show e q u a l b r e a k i n g o f b o t h b o n d s , u n e q u a l bonds and  azo  ,  results  were  kinetics.  o f c i s and  trans-  (XVI and X V I I )  have an I n t e r m e d i a t e s i t u a t i o n where t h e C - N bonds a r e  we  break-  -  ing  37 -  i n the t r a n s i t i o n state  sufficient sition  possibly  p o l a r i t y developes  t o d i f f e r e n t degrees and  i n the molecule  after the tran-  s t a t e t o make t h e p r o d u c t s s e n s i t i v e t o t h e s o l v e n t  u s e d . Such a model c o r r e c t l y p r e d i c t s  Photolysis ^-pyrazoline  o f c i s and  reaifio'n ^  ^  1  trans-3,.4-dlmethyl-3-earbomethoxy-  ( V I a n d V I I ) h a v e b e e n r e p o r t e d b y v a n Auken a n d  ( 1 2 ) t o g i v e s t e r e o s p e c i f I c a l l y c i s and t r a n s _ - l , 2 - d i -  Rinehart  methyl-l-carbomethoxycyclopropane major s i d e gelate  the o l e f i n  products a r e methyl  (X a n d X I ) r e s p e c t i v e l y , t h e  tiglate  (IV) and methyl a n -  (V) r e s p e c t i v e l y . /COOCH^ fC *  ^\  KJ^ V  HC ^ 3  k  ... O O C  X  H  H \  o  COOCH / \  K <fX/^m HoC v xi ^  1  3  3  X (3,4)  I  C  O  O  C  H  ^  H  y  _  M  C  H  CH3  3  IV ( 1 . 0 )  H ^  3  3  =  r  /  OOCH  3  c V  XI  VII  Photolysis A -pyrazoline 1  o f c i s and  V (1.0)  trans-3,5-dlmethyl-3-carbomethoxy-  (XVI and X V I I ) , c i s a n d t r a n s - 3 , 5 - d i m e t h y l - 3 -  acetyl-^"-pyrazoline the  (21.3)  (XVIII and XIX) resemble  very c l o s e l y to  p y r o l y s i s o f t h e same. The m a j o r d i f f e r e n c e  that,  the photolysis  retention  CH, 3  gave a h i g h e r y i e l d  observed i s  of cyclopropane with  o f the geometry present i n the pyrazoline,  p y r o l y s i s gave a. l o w e r y i e l d  and t h e  of cyclopropane with retention of  - 38 -  CH  H CH,  XVI,  Y=COOCR"  3  cis-olefin X V I I I , Y = COCH  3  CHo  XVII, XIX,  The  Y=COOCH Y=COCH  preferred  product  3  H /  trans-olefin  product  3  conformation  o f t h e p y r a z o l i n e isomers  t h e p s e u d o e q u a t o r i a l h y d r o g e n on C^ i n a b e t t e r  places  position  f o r m i g r a t i o n t o C,_ c o n c e r t e d w i t h n i t r o g e n e l i m i n a t i o n t h a n t h e pseudo a x i a l  hydrogen.  FIGURE X - S t e r e o c h e m i s t r y o f t h e f o r m a t i o n o f olefins  f r o m b. - p y r a z o l i n e s .  - 39 -  t h e geometry p r e s e n t ratios  XXV)  XVIII  XIX  and  KH  59*28  were  21:70  and  f o r the p h o t o l y s i s of  respectively. A similar  £OCH O  the  trans-1,2-dimethyl-l-acetylcyclopropane  o f c i s and  (XXIV and  I n t h e p y r a z o l i n e . F o r example,  I ^  solvent effect  3  A ^ C O C H C^"  3  on  the  JC0GH, H C^y\> w^ 3  3  ^"01  3 xxiv (59$)  XVIII  x  H C^'N^  P0CH  3  ^  N  3  served  c o m p o s i t i o n as o b s e r v e d i n t h e p h o t o l y s i s . The  c l o s e l y r e l a t e d but  not  compositions  It  3.  H  3 ^  ^  XXIV  (21$)  i n t h e p y r o l y s i s was  two  and  also  shown by  s o l v e n t In which  different  resulted.'  f o r m a t i o n o f t h e same I n t e r m e d i a t e as t h e p y r o l y s i s  o r due  to induced  tronically  excited  nance s p e c t r a differences  to a d i f f e r e n t  structural  amount o f a v a i l a b l e  f e a t u r e s from  I n t e r m e d i a t e . The  i n the chemical  shift  the p r i o r  n u c l e a r magnetic  positions  of the  con- .  with  ( T a b l e I ) o f t h e A ^ - p y r a z o l i n e s showed  on C / | , e s p e c i a l l y  ob-  p h o t o l y s i s and  i s p o s s i b l e the p h o t o l y s i s i n v o l v e s a d i f f e r e n t  v a r i a t i o n e i t h e r due  3  H  r e a c t i o n s t h e r e f o r e are  I d e n t i c a l as  p y r o l y s i s a t same t e m p e r a t u r e product  H  (70)  XXV  XIX product  (28$)  XXV  energy  elecresolarge  hydrogens  i n cis-3,5-dimethyl-3-acetyl-A*'-pyrazoline  _ 40 -  (XVIII), a n d c i s - 3 , 5 - d l m e t h y l - 3 - e a r b o m e t h o x y - A - p y r a z o l i n e ' (XVI) . F o r example, and  9 . 3 0 - f , t h o s e o f XVI a b s o r b e d  pared (XVII)  a t 7.57 tf  a t 7.68 •tf'and 9.14  com-  t o 8.28 'i and 8.56 tf f o r t h e t r a n s - e s t e r - p y r a z o l i n e a n d 8.53 tf f o r t h e t r a n s - k e t o - p y r a z o l i n e 1  differences ferences it  hydrogens i n XVIII absorbed  i n chemical s h i f t s  c o u l d w e l l be r e l a t e d  i n conformation i n these speeies.  Is obvious  that  the molecules  reaction with considerable  (XIX).  I f this  These  to d i f -  i s so t h e n  i n some c a s e s a r e e n t e r i n g  differences i n their  geometry.  -.41 -  VI.  VI-1.  General Melting  ing  statement p o i n t s and b o i l i n g  p o i n t s were d e t e r m i n e d  paratus  by t h e micro  Infrared  by a m i c r o s c o p i c m e l t i n g p o i n t a p -  inverted  capillary  p o i n t s were d e -  method.  s p e c t r a were m e a s u r e d w i t h a P e r k i n - E l m e r  spectrophotometer  fitted  N u c l e a r magnetic  w i t h sodium c h l o r i d e  resonance  V a r i a n A s s o c i a t e s M o d e l A-60 and  points are uncorrected. Melt-  ( R e i c h a r t , A u s t r i a ) and most b o i l i n g  termined  137  EXPERIMENTAL  Model  optics.  s p e c t r a were r e c o r d e d on a  spectrophotometer  Mr. P. H o r n . T e t r a m e t h y l s i l a n e was  used  by M r s . E . B r i o n  as  Internal  standard. The graph  vapor  phase chromatography u n i t s used  M o d e l A-90-P  M o d e l 226 The  ( p r e p a r a t i v e s c a l e ) and a  (analytical  VI-2.  N-Nitroso-N-ethyl  was  Perkin-Elmer  e l e m e n t a l m i c r o a n a l y s e s were p e r f o r m e d  o f Germany  (35)  Aero-  scale).  hardt  The  were an  by D r . A.  and b y M r s . A. A l d r i d g e and M r s . C. J e n k i n s .  urea  method f o r t h e p r e p a r a t i o n o f N - n i t r o s o - N - m e t h y l adapted  moles) o f urea of ethylamine  Bern-  w i t h some m o d i f i c a t i o n . T h r e e  was d i s s o l v e d  urea  h u n d r e d grams  i n a s o l u t i o n o f 123  g . (1.5  (5  moles)  h y d r o c h l o r i d e , 300 m l . o f w a t e r and a few d r o p s  of  - 42  -  c o n c e n t r a t e d h y d r o c h l o r i c a c i d . The under r e f l u x  per  was  boiled  f o r t h r e e hours a n d , v i g o r o u s l y f o r a  hour. A f t e r c o o l i n g o f 98  mixture  cent  t o room t e m p e r a t u r e ,  sodium n i t r i t e  divided  into  i c e and  a d d e d t o an  was  110  added and  quarter  (1.5  g.  concentrated  sulfuric  i n 110  acid  o f 17  solution  moles)  the mixture  s i x e q u a l p o r t i o n s . E a c h p o r t i o n was ice-cold  (0.17  g.  g. o f i c e w i t h  stirring  n i t r o s o - N - e t h y l u r e a , w h i c h r o s e t o t h e s u r f a c e as  pale  c r y s t a l s , was w a t e r and  collected  dried  by  t h r e e h o u r s ) . The  suction t i l l yield  of the t h e o r e t i c a l  VI-3.  on a f i l t e r  87  was  washed w i t h  constant weight g.  (0.75  Nyellow  lee-cold  (approximately  mole) o r 50  per  cent  yield.  grams  (O.285 mole) o f N - n i t r o s o - N - e t h y l u r e a  added t o v i g o r o u s l y s t i r r e d anhydrous ether-methanol hydroxide  ice-cold  (5 l) :  and  o f 300  solution  125  ml.  o f 40$  a t s u c h a r a t e t h a t t h e r e a c t i o n was  the r e a c t i o n  temperature  s o l u t i o n was  t h e aqueous l a y e r , washed w i t h 100  ml.  d r i e d w i t h anhydrous potassium hours.  The  yield  was  The  35-40 p e r  cent  for as  t h e r e a c t i o n s w i t h m e t h y l i s o p r o p e n y l k e t o n e and  methacrylate.  orange  decanted  pellets  of  control  of i c e - c o l d water  hydroxide  approximately  ml.  was  potassium  under  r e m a i n e d below 5°»  colored diazoethane-ether-methanol  by  at  Diazoethane Fifty  and  and  with  mole) o f  The  a r a t e t h a t the temperature  was  chilled  r e m a i n e d below 5 ° .  such  gently  from and  two estimated methyl  - 43 -  VI-4. Methyl  i s o p r o p e n y l ketone  A commercial  sample  (K a n d K L a b o r a t o r y , P l a i n s v i l l e ,  N.Y.) was p u r i f i e d by m i x i n g w i t h an e q u a l volume o f ethyl  ether with s t i r r i n g .  instantly trate  A polymer  and was f i l t e r e d  was d i s t i l l e d  with a b o i l i n g point  residue  precipitated  with f l u t t e d f i l t e r  a t atmospheric  anhydrous  p a p e r . The  fil-  p r e s s u r e and t h e f r a c t i o n  o f 9 5 ± 2 ° was c o l l e c t e d  and used  immedi-  ately.  VI-5.  S^-Dimethyl-S-acetyl-A  -pyrazoline  1  (XXIII)  To a n i c e - c o l d d i a z o e t h a n e - e t h e r - m e t h a n o l added t h e f r e s h l y with s t i r r i n g  distilled  methyl  u n t i l t h e orange  solution  i s o p r o p e n y l ketone  color  b.p.  56-57°/1.2  methyl  mm.  (50  Anal. Calcd. f o r F o u n d : C, The  59.60°  C  N 1  2  H, 8.22* N,  n.m.r. s p e c t r u m  on t h e q u a n t i t y o f  2  °  5  °> 59.97" H, 8 . 6 3 ; N, 19.99-  20.27.  (20$ v / v i n C C l ^ ) showed i t t o be a  m i x t u r e o f 40$ c i s a n d 60$ t r a n s i s o m e r s mated by t h e i n t e g r a l s two  isomers.  liquid,  used).  H 7  aspirator  to give a colorless  p e r cent based  I s o p r o p e n y l ketone  slowly  d i s a p p e a r e d . The s o l v e n t  m i x t u r e was removed by a f l a s h e v a p o r a t o r a t w a t e r p r e s s u r e and t h e r e s i d u e d i s t i l l e d  was  of the acetyl  ( s e e below) as e s t i -  methyl hydrogens  of the  - 44 -  VI-6.  S e p a r a t i o n o f c i s and t r a n s - 3 , 5 - d l m e t h y l - 3 - a c e t y l - A pyrazoline The  6-mm.  ( X V I I I and XIX)  3>5-dimethyl-3-acetyl-A -pyrazoline  u s i n g a N e s t e r and F a u s t 1 8 - i n c h by  distilled  spinning-band  still  a t 0.2  t o 0.3  immersed i n o i l b a t h m a i n t a i n e d b e t w e e n tire The  ( X X I I I ) was  1  fractionally  -  distillation,  the vapor  mm.  with the s t i l l pot  65-70°.  came o v e r a t  During the en-  32-35°/0.2-0.3  n.m.r. a n a l y s e s o f t h e l o w e r and h i g h e r b o i l i n g  mm.  fractions  showed t h e y c o n t a i n e d 8 l $ c i s - p y r a z o l i n e X V I I I and 87$  trans-  p y r a z o l i n e XIX r e s p e c t i v e l y . T h e s e a n a l y s e s were b a s e d  on t h e  integrals  o f the a c e t y l methyl  for  t h e e l s Isomer a n d a t 7.65  and  t r a n s geometric  of  n.m.r. s p e c t r a l  hydrogens a b s o r p t i o n s a t  <i f o r t h e t r a n s i s o m e r . The c i s  assignments  were b a s e d  on t h e c o m p a r i s o n  data w i t h those o f c i s and t r a n s - 3 , 5 - d i -  methyl-3-carbomethoxy-& -pyrazoline  (XVI and X V I I )  L  and  'J.fQ't  the stereospecifIc  1-acetylcyclopropane  (Table I)  f o r m a t i o n o f c i s and t r j n s - 1 , 2 - d i m e t h y l -  (XXIV a n d XXV) f r o m X V I I I and XIX r e -  s p e c t i v e l y by p h o t o l y s i s .  The  n.m.r. s p e c t r a l d a t a o f c i s a n d  3-acetyl-^-pyrazoline  VI-7.  ( X V I I I a n d XIX) a r e t a b u l a t e d  S e p a r a t i o n o f c i s and ^--pyrazoline  trans-3,5-dimethyl-  trans-3,5-dlmethyl-3-carbomethoxy-  (XVI and X V I I )  3,5-Dimethyl-3-carbomethoxy-^J"-pyrazoline (17)  i n Table I .  from d l a z o e t h a n e and methyl  m e t h a c r y l a t e was  (XX) p r e p a r e d fractionally  - 45 -  distilled  as d e s c r i b e d  f o r t h e s e p a r a t i o n o f c i s and  3,5-dimethyl-3-acetyl-A -pyrazoline  ( X V I I I and XIX)  1  cis  transto give  and t r a n s - 3 , 5 - d i m e t h y l - 3 - c a r b o m e t h o x y - ^ ' - p y r a z o l i n e  and X V I I )  of  93$  48-53°/0.1-0.3  between  chemical s h i f t s T  6.27  994-$ p u r e  and  XVI  and X V I I  showed  f o r the e s t e r methyl hydrogens  respectively,  t h e two  mm.  r e s p e c t i v e l y , at  and t h i s i s " t h e b a s i s  (XVI  temperature different a t 6.33  if and  for distinguishing  i s o m e r s . G e o m e t r i c a s s i g n m e n t s were b a s e d on t h e  photolysis  results  In which the  methoxy-A. - p y r a z o l i n e methoxycyclopropane  (X) and t h e  methyl-A^-pyrazoline methoxycyclopropane  cis-l,2-dimethyl-l-carbotrans_-3,5~dimethyl~3-carbo-  ( X V I I ) gave t r a n s - 1 , 2 - d i m e t h y l - l - o a r b o (XI) as main p r o d u c t , and t h e l o w e r  of the c i s - p y r a z o l i n e methyl groups a t  (XVI). gave  cis-3,5-dimethyl-3-carbo-  XVI  and  (40$)  due  to steric  yield  hindrance of the  C,-.  The n.m.r. s p e c t r a l d a t a o f c i s and 3-carbomethoxy-^? -pyrazoline -  (XVI and X V I I )  trans_-3,5-dimethylare tabulated i n  Table I .  VI-8.  trans-3,5-DImethyl-3-carbomethoxy-£J'-pyrazoline  hydro-  bromide. (XXII) To a m i x t u r e o f 0.4 methoxy-A^-pyrazoline was  added  ml. of  trans-3,5-dimethyl-3-carbo-  (XVII) i n 3 ml. o f anhydrous  slowly with constant s t i r r i n g  e t h y l e t h e r s a t u r a t e d w i t h anhydrous p a l e y e l l o w p r e c i p i t a t e was to give  0.75  a s o l u t i o n of  hydrogen bromide  recrystallized  g. o f w h i t e c r y s t a l s ,  ethyl  m.p.  ether  anhydrous gas.  The  from e t h a n o l - e t h e r  152-153°.  Larger  - 46 -  c r y s t a l s were o b t a i n e d by  slow  recrystalllsation  A n a l . C a l c d . f o r C ^ H ^ N g O g B r * C,  35.47°  Founds C,  VI-9.  H,  5.32)  Thermal p y r o l y s i s  35.46;  from  ethanol.  5.53?  H,  11.82.  N,  12.16.  N,  3,5-dimethyl-3-aeetyl-A *~pyrazoline  of  ]  (XXIII) The  I n j e c t o r port of the vapor used  as  phase chromatography  (Aerograph  M o d e l A-90-P) was  the apparatus  pyrolysis.  A sample o f t h e p y r a z o l i n e X X I I I was  t h e i n j e c t o r p o r t by means o f a h y p o d e r m i c lysis  p r o d u c t s were e l u t e d  occurred  and  collected  through  f r a c t i o n was  a mixture  o f two  ponents have been i d e n t i f i e d point, refractive  i t was  f o r thermal  injected  s y r i n g e , the  found  t h a t the  second s i x com-  i n d i c a t e d b e l o w , where  index, r e t e n t i o n time  i n the vapor  boiling  phase  ehromatogram u s i n g a 1 0 - f t . d i d e c y l p h t h a l a t e column o f quarter inch diameter flow  p r e s s u r e a t 48  total  products  a t 140°,  255°  i n j e c t o r at  p . s . I . , product  pyro-  separately. Five  components. A l l t h e s e as  into  t h e column where s e p a r a t i o n  at the c o l l e c t o r  f r a c t i o n s were o b t a i n e d and  unit  composition  a r e g i v e n . ( s e F i g u r e V I I , P.  with  one  helium  i n per cent  of  14).  119-120°, o P4 (27) b.p. I I 8 . 3 - I I 8 . 6 /746 mm., ng 1.4390),  2 , 3 , 5 - T r i m e t h y . l - A - d i h y d r o f u r a n (XXIX) : b . p . 2  24 n £ 1.4305 ( l i t . 6.2  m i n u t e s and  ( s ) due and  9.63  spectrum  9$.  I n f r a r e d bands  to carbon-carbon JX (s) due (30$  v/v  (5$  v/v  i n CCl^)  double-bond s t r e t c h i n g ,  to v i n y l  ether stretching  i n CCl,,) showed s i g n a l s  8.21  (28).  of v i n y l  5.87^  at  The  M  (s) n.m.r.  methyl  - 47 -  h y d r o g e n s a t 8.43  8.79^  IT* ( m u l t i p l e t ) , C,_ m e t h y l h y d r o g e n s a t  ( d o u b l e t w i t h J-«6.1 c . p . s . ) , C^ h y d r o g e n s a t 7.40 tf (two d o u b l e t s ) and 7.98 tf (two d o u b l e t s ) and C,_ h y d r o g e n a t (Sextet w i t h f u r t h e r constituted  A ~35.5 A B  s p l i t t i n g ) . The hydrogens at  a t y p i c a l ABX  system  (29)  c . p . s . , AgxCs-109 c . p . s . ,  c . p . s . and  c.p.s. (Figure  J  and  with ^ A X ™ ^ * 1  A B  5.59^  5  C  ^ l 4 . 5 c.p.s., J  C^ «P- «* S  A X  ^8.0  I X ) . These c h e m i c a l s h i f t s  2 are  at expected p o s i t i o n s ( X X X I I I ) (30)  furan  5.55  plet),  tf  tf  c . p . s . ) due t o C  and  t o 2-methyl-k, - d i h y d r o -  whose c h e m i c a l s h i f t s are at 8.30  ( m u l t i p l e t ) , 7.47  plet with J 2 9 . 3 hydrogen,  as compared  hydrogens  (multiplet) 2  and 5,78  tf tf  (multi(tri-  m e t h y l h y d r o g e n s , C^ v i n y l  respectively.  A n a l . C a l c d . f o r C 7 H 1 2 0 « C,  74.95"  H,  10.78. F o u n d : C,  74.951 H, 1 0 . 9 0 . cis-3-Methyl-3-hexen-2-one  (XXX): b.p. 1 4 5 - 1 4 5 . 5 ° ,  1.4370, 1 2 . 2 m i n u t e s and 6$. I n f r a r e d  5.91><-  ( s ) and 6 . l 8 y U  (5$  n ^ 2  v / v I n C C l ^ ) bands  (w) a t t r i b u t a b l e t o t h e  at  o(,/£-unsaturated  e a r b o n y l and c a r b o n - c a r b o n d o u b l e - b o n d s t r e t c h i n g  respectively.  The n.m.r. s p e c t r u m (10$ v / v i n C C l ^ ) showed peaks o f a c e t y l m e t h y l h y d r o g e n s a t 7.86 tf ( s i n g l e t ) , v i n y l m e t h y l h y d r o g e n s a t 8.12 tf ( m u l t i p l e t ) , m e t h y l e n e h y d r o g e n s a t 7.73 alkyl  m e t h y l h y d r o g e n s a t 9.02'tf ( t r i p l e t  tf  (multiplet),  w i t h J ^7.3  c.p.s.)  and v i n y l h y d r o g e n a t 4.44 tf ( m u l t i p l e t ) . G e o m e t r i c a s s i g n m e n t is  discussed  below.  Anal. Calcd. f o r C^H^O:  75.021 H, 1 0 . 7 7 .  C,  74.95°  H,  10.78. Founds  C,  - 48  -  trans-3-Methyl-3-hexen-2-one;  (XXXI): b.p.  156.5-158°, n ' 2  3  1.4481, 17.7 m i n u t e s and 7$. I n f r a r e d s p e c t r u m (5$ v / v i n C C l ^ ) showed a b s o r p t i o n s a t 5.96 saturated  A  ( s ) and 6.07  (w) due t o  ^^-un-  c a r b o n y l and c a r b o n - c a r b o n d o u b l e - b o n d s t r e t c h i n g r e -  s p e c t i v e l y . The n.m.r. s p e c t r u m (10$ o f a c e t y l m e t h y l h y d r o g e n s a t 7.81  8.93  hydrogens at  h y d r o g e n s a t 8.39 (multiplet)  ^  (triplet  with  1*  v / v i n C C l ^ ) showed  peaks  ( s i n g l e t ) , a l k y l methyl  J<*7.5 c . p . s . ) , v i n y l m e t h y l  'c ( m u l t l p l e t ) , m e t h y l e n e h y d r o g e n s a t 7.76't  and v i n y l h y d r o g e n a t 3.52  ^ (multlplet).  The g e o m e t r i c a s s i g n m e n t s f o r t h e c i s and t r a n s - 3 - m e t h y l 3-hexen-2-one shift  (XXX and XXXI) were b a s e d on t h e l o w e r c h e m i c a l  o f t h e v i n y l p r o t o n i n X X X I . S i n c e i n XXXI, t h e v i n y l  p r o t o n I s c i s t o t h e c a r b o n y l and h e n c e c l o s e r t o t h e ic the  a n i s o t r o p y o f the carbon-oxygen double-bond which  diamagnetdeshields  v i n y l p r o t o n t o a g r e a t e r e x t e n t t o g i v e a low <f-value Anal. Calcd. f o r C H  (32).  0* C, 74.95* H, 10.78. F o u n d : C,  75.03J H, 10.81. cis-l,2-Dimethyl-l-acetylcyclopropane  152.5°, n  1.4376, 15.7 m i n u t e s and 44$. I n f r a r e d  2 i |  CCljj) s p e c t r u m showed bands stretching  (XXIV): b.p.  at  (5$ v / v i n  5.96//. ( s ) and 9.76/U. (tn) due t o  o f c a r b o n y l c o n j u g a t e d t o c y c l o p r o p a n e r i n g and  p r o p a n e r e s p e c t i v e l y . The n.m.r. s p e c t r u m (20$  G  1  m e t h y l h y d r o g e n s a t 8.72  h y d r o g e n s a t 8.82  t! ( m u l t i p l e t  r i n g h y d r o g e n s a t 8.68  i.  cyclo  v/v i n CCl^)  showed t h e f o l l w i n g p e a k s , a c e t y l m e t h y l h y d r o g e n s a t 8.00 (singlet),  151.5-  (multiplet), C  w i t h main peak a t 8.84  't (two h y d r o g e n s , m u l t l p l e t  2  *t methyl  t!), other  u n d e r C-^  - 4 methyl hydrogens Assignment  9  -  s i g n a l ) a n d 9.74 tf (one h y d r o g e n ,  o f geometry  will  multiplet)-.  be d i s c u s s e d b e l o w . R e p e a t e d  ele-  m e n t a l m i c r o a n a l y s i s gave low v a l u e o f c a r b o n c o m p o s i t i o n . trans-l,2-Dimethyl-l-acetylcyclopropane yl-4~hexen-2-one  (XXXII)t  t h e s e two components e l u t e d t o g e t h e r  w i t h r e t e n t i o n t i m e o f 10.5 total  (XXV) and 3-meth-  minutes,  t h e y c o n s t i t u t e d 34$ o f t h e  p r o d u c t s . A n a l y t i c a l v a p o r phase  chromatographic  showed t h e m i x t u r e t o c o n s i s t o f 85$ o f XXV and 15$ B r o m i n a t i o n o f t h e m i x t u r e u s i n g 5$ b r o m i n e  analysis  o f XXXII.  i n carbon  tetra-  c h l o r i d e gave t r a n s - 1 , 2 - d i m e t h y l - l - a a e t y l c y c l o p r o p a n e (XXV) and trans-3-methyl-3-hexen-2-one v a p o r phase the  chromatography  (XXXI) as i n d i c a t e d b y p r e p a r a t i v e  s e p a r a t i o n . The n.m.r. s p e c t r u m o f  o r i g i n a l m i x t u r e i n d i c a t e d t h e p r e s e n c e o f XXV and XXXII  and w i l l  be d i s c u s s e d  s e p a r a t e l y below.  A n a l . C a l c d . f o r C ^ H ^ O : C,  74.95"  H,  10.78.  Found* C,  74.87° H, 10.91. trans-l,2-Dimethyl-l-acetyloyclopropane  137°, to  1.4275.  carbonyl  (5$  Infrared  v/v i n C C l ^ ) band a t  gens a t 7.86 tf ( s i n g l e t ) , C  methyl hydrogens  due  spectrum  of a c e t y l methyl  hydro-  a t 8.62 tf ( s i n -  a t 9.O3 tf ( m u l t i p l e t ) ,  C^ m e t h y l h y d r o g e n s  and C^  a t two s e t s o f m u l t i p l e t i n t h e r e g i o n between 8.75 tf  hydrogens and  1  136.5-  5-90^  c o n j u g a t e d t o c y c l o p r o p a n e r i n g . The n.m.r.  (20$ v / v i n C C l ^ ) showed t h e a b s o r p t i o n  glet),  (XXV) *• b . p .  9.60 C. r  The assignment  o f geometry  methyl-.1-a c e t y l c y c l o p r o p a n e  t o c i s and t r a j i s _ - l , 2 - d i -  (XXIV and XXV) was b a s e d on t h e com-  p a r i s o n o f t h e i r n.m.r. s p e c t r a t o t h o s e o f t h e a n a l o g o u s propanes,  eyclo-  t h e c i s and t r a n s - 1 , 2 - d i m e t h y l - l - c a r b o m e t h o x y c y c l o p r o -  - 50 -  pane  (X and. XI)  3-Methyl-4-hexen~2-one been i s o l a t e d c a t i o n . The  to give  (XXXII) '* t h i s  sufficient  p r e s e n c e o f XXXII was  acetylcyclopropane by  assigned  those  i n d i c a t e d by  h y d r o g e n s a t 4.57 *£  cated  f  8.92  *t ( d o u b l e t w i t h  ( m u l t i p l e t ) and  sample t o be  a  vinyl  absorption  at  The  (XVIII thermal are  and  XIX).  methyl hydrogens  and  at  indi-  the  the olefin  (XVIII  and  tra_ns-3,5-dimethyl-3-acetyl-  XIX)  f o r the  thermal  (XXIII)  was  3,5-  p y r o l y s i s of u s e d ..for t h e  thermal  trans-3,5-dimetbyl-3-acetyl-^"-pyrazoline same p r o d u c t s  in different  r a t i o . These  as  the  results  II.  V I - 1 1 . V a p o r p h a s e p y r o l y s i s o f c i s and  1  J<*7 c . p . s . ) , v i n y l  at 7.97^  T h e s e r e a c t i o n s gave t h e  i n Table  (singlet),  ketone because of  p y r o l y s i s of XXIII but  recorded  and  4.57'if.  same p r o c e d u r e as  o f c i s and  't  -unsaturated  dimethyl-3-acetyl-/^"-pyrazoline pyrolysis  observed  n.m.r. s p e c t r u m  V I - 1 0 . T h e r m a l p y r o l y s i s o f c i s and ^-pyrazoline  ob-  c . p . s . ) . The  h i g h a c e t y l methyl hydrogens a b s o r p t i o n proton  identifi-  trjans-1,2-dimethyl-1-  f o l l o w i n g were r e a d i l y  with J ^ 4 . 8  (doublet the  the  not  n.m.r.  f o l l o w s , a c e t y l m e t h y l h y d r o g e n s a t 7.97  as  methyl hydrogens at  8.32  the  (XXV). Some s i g n a l s o f X X X I I were  o f XXV,  .  compound had  sample f o r c o m p l e t e  s p e c t r u m - o f t h e m i x t u r e o f XXXII and  seured  (12)  whose g e o m e t r y have b e e n d e t e r m i n e d  acetyl-A-pyrazoline  (XVIII  and  trans_-3,5-dimethyl-3XIX)  "  - 51 -  The liter  apparatus  round  f o r the vapor  phase p y r o l y s i s  f l a s k equiped w i t h a ground  s t o p c o c k and  (45-mm. x 10-mm.) o p p o s i t e t h e s t o p c o c k . T h r e e sample o f X V I I I f i n g e r and evacuated  o r XIX  n i t r o g e n , and  below 0 . 3 mm. The r e a c t i o n  cooled with l i q u i d  t h e f l a s k was t h e n i n an  I t was t h e n  t h e p r o d u c t s were c o l l e c t e d  nitrogen. Fifty  e t h e r -w«rs a d d e d , and  microliter  f l a s k was h e a t e d  t o 125° f o r t h i r t y m i n u t e s .  ed t o a vacumn l i n e and  a finger  i n a c a p i l l a r y t u b e was p l a c e d i n t h e  cooled with l i q u i d  oven p r e h e a t e d  was a one-,  connect-  i n a U-tube  m i c r o l i t e r s o f anhydrous  t h e m i x t u r e was a n a l y s e d b y a n a l y t i c a l  vapor  phase chromatography u s i n g a 150-ft. x 0.01-in. P e r k i n -  Elmer  column  "R" a t 100° w i t h n i t r o g e n f l o w p r e s s u r e o f 12 p . s .  i.  T h e a n a l y s e s showed t h a t  of  c i s and  XIX)  the vapor  phase p y r o l y s i s  reactions  trans_-3,5-dimethyl-3-acetyl-£?"-pyrazoline  (XVIII  gave t h e same p r o d u c t s a s t h e t h e r m a l p y r o l y s i s  o f the  same compound b u t  i n d i f f e r e n t r a t i o . These r e s u l t s  and  are r e c o r d -  ed i n T a b l e I I .  VI-12.  Liquid  phase p y r o l y s i s  pyrazoline Nine  and  of 3,5-dimethyl-3-acetyl-/^ L  (XXIII)  a h a l f grams o f X X I I I  equiped w i t h a water c o o l e d condenser pyrolysis  started  c e a s e d t o come o f f . The  t h e t h e o r e t i c a l amount. The vapor  was h e a t e d  flask  i n an o i l bath,  a t 90° w i t h t h e e v o l u t i o n o f n i t r o g e n gas a n d  became v i g o r o u s a t 1 0 5 ° . The gas  i n a 25 m l . r o u n d  h e a t i n g was s t o p p e d when n i t r o g e n y i e l d was 7 g . o r 93 p e r c e n t o f m i x t u r e was s e p a r a t e d b y p r e p a r a t i v e  phase chromatography u s i n g a 10-ft. d i d e e y l p h t h a l a t e  52 -  c o l u m n o f one  quarter inch diameter  p r e s s u r e a t 48 pyrolysis-of sult  p.s.i.  a t 140  with helium  t o g i v e t h e same p r o d u c t s  t h e same compound b u t  as t h e  flow thermal  i n d i f f e r e n t r a t i o . The  re-  i s recorded i n Table I I .  vT-13* L i q u i d p h a s e p y r o l y s i s o f c i s and t r a n s _ - 3 , 5 - d i m e t h y l - 3 •• a c e t y l - A - p y r a z o l i n e 1  One mm.  pyrex  lution  heated  o f n i t r o g e n gas  VI-14.Photolysis A mixture  was  a 50  of XVIII  o r XIX  ceased.  Product  results  of 1 ml.  of XXIII  f l a s k equiped  under r e f l u x  when a sample was  and  Injected into  25  ml.  amount o f n i t r o g e n t h a t e v o l v e d connected  t o a gas  measuring  distilled  o f f at atmospheric  (XXIII)  of anhydrous  o f p h o t o l y s i s was chromatogram  by m e a s u r i n g  the  phase theoretical  (the top of the condenser  b u r e t ) . Most o f t h e s o l v e n t and  was was  the concentrate  e i t h e r p r e p a r a t i v e or a n a l y t i c a l vapor  as d e s c r i b e d a b o v e . The  ether  condenser  the p r e p a r a t i v e vapor  pressure  as  m e r c u r y lamp f o r s i x  completion  or a l t e r n a t e l y ,  pro-  i n Table I I .  with a water c o o l e d  c o n d i t i o n . The  chromatography u n i t  tography  of the  8-  evo-  phase chromatography  by t h e a b s e n c e o f n i t r o g e n peak i n t h e  a n a l y s e d by  the  of 3 * 5 - d i m e t h y l - 3 - a c e t y l - A - p y r a z o l i n e  ml. round  determined  until  composition  are recorded  i r r a d i a t e d w i t h a 450-watt H a n o v i a  hours  i n a 150-mm. x  i n an o i l b a t h a t 100°  a n a l y s e d by a n a l y t i c a l v a p o r  d e s c r i b e d a b o v e . The  in  XIX)  quarter m i l l i l i t e r t u b e was  d u c t s was  ( X V I I I and  same p r o d u c t s  was  p h a s e chroma-  but a t ' d i f f e r e n t  - 53  compositions than the l i q u i d pound r e s u l t e d .  The r e s u l t  VI-15. P h o t o l y s i s pyrazoline  i s recorded i n Table I I .  ( X V I I I a n d XIX)  0.5ml.  o f X V I I I o r XIX and  e t h e r I n a 25 m l . r o u n d  condenser  was p h o t o l y s i s  photolysis,  o f t h e same com-  o f c i s and t r a n s - 3 , 5 - d i m e t h y l - 3 - a c e t y l - / J " -  A mixture of drous  phase p y r o l y s i s  without  5  m l . o f anhy-  f l a s k equiped w i t h a water  as d e s c r i b e d a b o v e . The m i x t u r e  cooled after  c o n c e n t r a t i n g t h e s o l v e n t , was a n a l y s e d by  a n a l y t i c a l v a p o r phase c h r o m a t o g r a p h y .  The r e s u l t s  are recorded  in Table I I .  VI-16. Vapor  phase p y r o l y s i s  o f c i s and  carbomethoxy-A -pyrazoline 1  The and  same p r o c e d u r e  tical  f o r the vapor  as t h e v a p o r  phase p y r o l y s i s  of c i s  phase p y r o l y s i s  o f XVI and X V I I .  Analy-  v a p o r p h a s e c h r o m a t o g r a m showed t h e same p r o d u c t s as t h e  v a p o r phase p y r o l y s i s  are  (XVI and X V I I )  t r a n s - 3 , 5 - d i m e t h y l - 3 - a c e t y l - / ^ - p y r a z o l i n e ( X V I I I .and XIX)  was u s e d  line  trans_-3,5-dimethyl-3-  o f 3j5-dimethyl-3-carbomethoxy-£^-pyrazo-  (XX) b u t I n d i f f e r e n t r a t i o  (17)  resulted.  These  results  recorded i n Table I I I .  V I - 1 7 . L i q u i d phase p y r o l y s i s o f c i s and t r a n s - 3 , 5 - d i m e t h y l - 3 carbomethoxy-A-pyrazoline solvents  (XVI a n d X V I I )  i n various  - 54 -  A m i x t u r e od 0.2 m l . o f XVI o r X V I I a n d 20 m l . o f s o l v e n t (30-cm. x 2.5-cm.) w h i c h h a d b e e n  In a s e a l e d tube  e v a c u a t e d t o below one  0.1  mm. was h e a t e d I n a n o v e n a t  and a h a l f h o u r s . F o r v o l a t i l e  moved b y d i s t i l l a t i o n condition, v a p o r phase  f°  s o l v e n t s , t h e s o l v e n t was r e -  chromatography.  For the solvent  reflux  and s i m i l a r l y  p y r o l y s e s were c y c l o h e x a n e (33.6  results  formamide, t h e p r o -  on a vacumn l i n e  b y pumping  analysed. Solvents ( d i e l e c t r i c  s t a n t s a t 20° a r e g i v e n i n p a r e n t h e s e s (2.07  D), a c e t o n i t r i l e a r e summarized  (44))  used  con-  i n these  D ) , e t h y l e t h e r (4.34 D ) , (37.5  D) a n d formamide  (109 D ) .  i n Table IV.  V I - 1 8 . P h o t o l y s i s o f t r a n s - 3 , 5 - d l m e t h y l-3-carbomethoxy~£i"pyrazoline The  (XVII) a t v a r i o u s  temperatures.  apparatus f o r these r e a c t i o n s  i s shown i n F i g u r e X I .  A m i x t u r e o f 0.2 ml o f X V I I a n d 5 m l . o f a n h y d r o u s placed  i n t h e r e a c t i o n v e s s e l A, t h e c e n t r i f u g a l  t u r n e d on w h i c h  pumped t h e m o b i l e c o o l i n g  I n D and t h e temperature  e t h e r was  pump F was  solution ethanol  through F, I i n t o B and back t o E . A . s u i t a b l e placed  r  t h e c o n c e n t r a t e d sample was a n a l y s e d b y a n a l y t i c a l  f o r two h o u r s  These  125-130°  t h r o u g h a s p i n n i n g - b a n d column u n d e r  d u c t s were removed f r o m t h e s o l v e n t  methanol  previously  c o o l i n g a g e n t was  a t E was t a k e n a s t h a t  p h o t o l y s i s . As soon a s t h e t e m p e r a t u r e  of the  a t E came t o c o n s t a n t ,  the mercury  lamp G ( H a n o v i a , 450-watt) was t u r n e d on a n d t h e  temperature  a t D was l o w e r e d a few d e g r e e s  temperature  a t E c o n s t a n t . I r r a d i a t i o n was t e r m i n a t e d when t h e  theoretical  amount o f n i t r o g e n g a s h a d e v o l v e d . T h i s  i n o r d e r t o keep t h e  experiment  - 55 -  r  A  - Reaction vessel,  B  - Cooling  13-mm. x 150-mm.  jacket  CL. - A i r j a c k e t E  - Dewar f l a s k w i t h e t h a n o l  D - Dewar f l a s k w i t h c o o l i n g P  solution  agent  - C e n t r i f u g a l pump  Q _ 450-watt H a n o v i a H - Gas m e a s u r i n g I  as m o b i l e c o o l i n g  - Cooling  m e r c u r y lamp  buret  coil  FIGURE X I - A p p a r a t u s f o r p h o t o l y s i s  a t low t e m p e r a t u r e .  - 56 -  had been performed a t t h r e e d i f f e r e n t  temperatures, 0 ,  -20  o and  -55  using  ice-salt,  c a r b o n t e t r a c h l o r i d e - D r y I c e and  c h l o r o f o r m - D r y I c e r e s p e c t i v e l y , as c o o l i n g a g e n t s a t D. A l l r e a c t i o n p r o d u c t s , w i t h o u t c o n c e n t r a t i n g t h e s o l v e n t , were a n a l y z e d by a n a l y t i c a l sults  a r e summarized  v a p o r p h a s e c h r o m a t o g r a p h y and t h e i r r e -  i n Table  V I - 1 9 . P h o t o l y s i s o f c i s and  1  A.-pyrazoline The g r a p h was was  V. trans-3,5~dimethyl-3-carbomethoxy-  (XVI and X V I I ) i n formamide a t  same p r o c e d u r e as d e s c r i b e d  22-23°.  These r e s u l t s  o  i n the preceeding  u s e d f o r t h e s e p h o t o l y s e s . The  water at  23  cooling  are recorded  para-  agent a t D i n Table  V.  VI-20. P a r t i a l photolysis of trans-3,5-dimethyl-3-carbomethoxy^-pyrazollne A mixture of e t h e r i n a 25  (XVII)  1  g. o f XVII  was  and  10  ml. of anhydrous  ml. round f l a s k equiped w i t h a water c o o l e d  d e n s e r whose t o p end was irradiated  (99+$)  c o n n e c t e d t o a gas m e a s u r i n g b u r e t  w i t h a 450-watt H a n o v l a m e r c u r y lamp. The  t e r m i n a t e d when 75  ml.  (50  per cent  of the  c o n n e c t e d t o a vacumn l i n e  theoretical  t o removed t h e s o l v e n t  p r o d u c t s f r o m p h o t o l y s i s . The r e c o v e d p y r a z o l i n e was n.m.r. w h i c h showed t h a t  t h e n.m.r. s p e c t r a  p y r a z o l i n e and t h e s t a r t i n g to  each  other.  was  irradiation  amount) o f n i t r o g e n gas had e v o l v e d , and t h e r e s u l t i n g was  con-  solution and t h e  analysed  by  of the recovered  pyrazoline wecfcpractically  identical  -57  VI-21.  Partial  liquid  -  phase p y r o l y s i s  carbomethoxy-fc, -pyrazoline 1  One  gram o f X V I I  (99+$)  c o n n e c t e d t o a gas m e a s u r i n g  (XVII)  i n a 100-mm. x 13-mm. p y r e x  p r o d u c t s i n a vacumn l i n e ,  a n a l y s e d b y n.m.r. w h i c h  t h e r e c o v e r e d p y r a z o l i n e and cally  (50 p e r c e n t o f t h e  theo-  amount) o f n i t r o g e n gas h a d e v o l v e d . A f t e r r e m o v i n g  pyrolysis was  tube  b u r e t was h e a t e d t o 95° a t an' o i l  b a t h . H e a t i n g was s t o p p e d when 75 n i l . retical  of trans-3,5-dlmethyl-3-  identical  the  the recovered p y r a z o l i n e  showed t h a t  t h e n.m.r. s p e c t r a o f  the s t a r t i n g  pyrazoline  wei^.practi-  t o each o t h e r .  VI-22. K i n e t i c Studies o f the p y r o l y s i s o f 3,5-dimethyl-3-carbomethoxy-A^-pyrazoline The  1  apparatus  (XX)  at various solvents  c o n s i s t e d o f a 150-mm. x 13-mm. p y r e x  whose t o p end was c o n n e c t e d t o a gas m e a s u r i n g liters 0.2  o f solvent  ml.  i n t h e t u b e was h e a t e d  o f XX was a d d e d i n t o t h e s o l v e n t  volume o f n i t r o g e n e v o l v e d and It  has b e e n shown (45) t h a t  pyrazoline  i s e q u a l t o ( l o g 2)/m,  log  in  of A -pyrazolines gives 1  the h a l f - l i f e ,  order plot  (V<»/%o-Vfc) v e r s e s t i m e , t . T h i s p y r o l y s i s  tetraline,  n i t r o b e n z e n e and  series  respectively  t | , o f the  o f the reaction  quantity o f XX had  of solvents, di-n-butyl ether,  f o r m a m i d e , and  the h a l f - l i v e  t h e s e s o l v e n t s h a d b e e n f o u n d t o b e 2 6 . 2 , 29.0,  minutes,  ,  and p y r o l y s i s b e g u n . T h e  where m i s t h e s l o p e o f t h e  obtained by the f i r s t  b e e n done i n t h e f o l l o w i n g  o  i n a n o i l b a t h t o 1C0-1  the p y r o l y s i s  order k i n e t i c s , and that  line  milll-  t h e t i m e were r e c o r d e d a t i n t e r v a l s .  good f i r s t  straight  buret. Six  tube  (Figure X I I ) .  o f XX  43.6 and 83.1  1.0  30  o  6o TIME  FIGURE X I I - F i r s t ~~  ~~  order plot  120  90  of l o g  150  (Minutes)  £2_— v s . t i m e V  Yoo -  f o r the p y r o l y s i s  t  dimethyl-3-carbomethoxy-i^'-pyrazoline  in. v a r i o u s s o l v e n t s .  of  3,5-  - 59 -  VI-9a. 2 , 4 - D i n i t r o p h e n y l hydrazones To a m i x t u r e o f f i f t y  m i c r o l i t e r s o f ketone and 3 n i l . o f  2 , 4 - d l n i t r o p h e n y l hydrazirre-dlglyme s o l u t i o n drops o f concentrated h y d r o c h l o r i c allowed t o stand  f o r at least  acid  24 h o u r s  (36)  was added 2  a n d t h e m i x t u r e was (otherwise o i l y  r e s u l t e d when w a t e r was a d d e d ) . Water was t h e n added with s t i r r i n g  till  cloudy, p r e c i p i t a t i o n normally  residue  dropwise  completed  a f t e r two o r t h r e e h o u r s . The p r e c i p i t a t e was c o l l e c t e d a n d recrystallized  f r o m d i g l y m e - w a t e r . The m e l t i n g p o i n t s  2,4-DNPH d e r i v a t i v e s cis  of the  of 2,3,5~trimethyl-A -dihydrofuran 2  and t r a n s - l , 2 - d l m e t h y l - l - a c e t y l c y c l o p r o p a n e  (XXIX),  (XXIV a n d XXV) 0  0  and c i s - 3 - m e t h y l - 3 - h e x e n - 2 - o n e (XXX) were 295-8 , 118.5-119.5 o , 0 307-9 a n d 156.5-157 r e s p e c t i v e l y , t r a n s - 3 - m e t h y l - 3 - h e x e n - 2 one gave two 2,4-DNPH d e r i v a t i v e s . "  one p r e c i p i t a t e d  before  o w a t e r was added, m.p.  158.5-159  a f t e r w a t e r was a d d e d , m.p. derivatives the  »  and t h e o t h e r  156-156.5°.  precipitated  T h e s e two 2,4-DNPH  o f trans-3-methyl-3-hexen-2-one  (XXXI) were n o t  same a s i n d i c a t e d by t h e i r mixed m e l t i n g p o i n t ,  and b y t h e f a c t  that  the second d e r i v a t i v e  154-157°,  precipitated  a f t e r w a t e r was a d d e d . I t h a s b e e n shown (42,43)  only  t h a t *(,^-un-  z. s a t u r a t e d k e t o n e s g i v e two 2,4-DNPH d e r i v a t i v e s , A - p y r a z o l i n e and s y n - a l k y l 2,4-DNPH. Hence o n e ^ t h e two 2,4-DNPH d e r i v a t i v e s 2 of  XXXI o b t a i n e d c o u l d b e a A - p y r a z o l i n e , and t h e o t h e r a  s y n - a l k y l 2,4-DNPH.  •  BIBLIOGRAPHY  1. E . B u e h n e r , M. F r i t s c h , 273, 214 (1893),.  A. P a p e n d i e c k a n d H. W i t t e r , Ann.,  2.  K. v o n Auwers  and E. 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