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Solvent effect on the position of Olefin equilibrations and additivity of free energy contributions of… Kaushal, Dharam Paul 1974

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SOLVENT EFFECT ON THE POSITION OF OLEFIN EQUILIBRATIONS AND A D D I T I V I T Y OF FREE ENERGY CONTRIBUTIONS OF V I C I N A L GROUPS b y DHARAM PAUL KAUSHAL B . S c . ( H o n s . ) , P a n j a b U n i v e r s i t y , I n d i a , 1965 M . S c , P a n j a b U n i v e r s i t y , I n d i a , I 9 6 6 A THESIS SUBMITTED I N P A R T I A L FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY i n t h e DEPARTMENT OF CHEMISTRY We a c c e p t t h i s t h e s i s as c o n f o r m i n g t o t h e r e q u i r e d s t a n ^ r d ^ * THE U N I V E R S I T Y OF B R I T I S H COLUMBIA May, 197^  In p r e s e n t i n g t h i s t h e s i s i n p a r t i a l f u l f i l m e n t o f t h e r e q u i r e m e n t s f o r a n a d v a n c e d d e g r e e a t t h e U n i v e r s i t y o f B r i t i s h C o l u m b i a , I a g r e e t h a t t h e L i b r a r y s h a l l m a k e i t f r e e l y a v a i l a b l e f o r r e f e r e n c e a n d s t u d y . I f u r t h e r a g r e e t h a t p e r m i s s i o n f o r e x t e n s i v e c o p y i n g o f t h i s t h e s i s f o r s c h o l a r l y p u r p o s e s may be g r a n t e d by t h e H e a d o f my D e p a r t m e n t o r by h i s r e p r e s e n t a t i v e s . I t i s u n d e r s t o o d t h a t c o p y i n g o r p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l n o t be a l l o w e d w i t h o u t my w r i t t e n p e r m i s s i o n . D e p a r t m e n t T h e U n i v e r s i t y o f B r i t i s h C o l u m b i a V a n c o u v e r 8, C a n a d a - i i -ABSTRACT The e f f e c t o f s o l v e n t : on t h e e q u i l i b r i u m p o s i t i o n f o r a number o f c i s - t r a n s p a i r s o f d i - and t r i s u b s t i t u t e d h a l o e t h y l e n e s a n d u n s a t u r a t e d n i t r i l e s h a v e b e e n i n v e s t i -g a t e d i n c a r b o n t e t r a c h l o r i d e a n d p e n t a n e b y t h e p h o t o -i n d u c e d b r o m i n e - c a t a l y z e d r e a c t i o n . T h e s e e q u i l i b r i u m v a l u e s h a v e b e e n c o m p a r e d t o t h e v a l u e s f o r n e a t s a m p l e s . I n a l l c a s e s i t h a s b e e n o b s e r v e d t h a t t h e p r o p o r t i o n o f t h e more p o l a r i s o m e r ( h i g h e r d i p o l e moment) o f a p a i r o f i s o m e r s d e c r e a s e d a nd t h e p r o p o r t i o n o f t h e l e s s p o l a r i s o m e r i n c r e a s c e d i n t h e n o n - p o l a r s o l v e n t s . The b r o m i n e - c a t a l y z e d e q u i l i b r i u m d a t a f o r n i n e 1 , 2 - d i s u b s t i t u t e d o l e f i n s ( h a v i n g B r , C l , CN, CH^ g r o u p s ) h a v e b e e n o b t a i n e d a s n e a t a n d a s 10% s o l u t i o n s i n c a r b o n t e t r a c h l o r i d e a n d p e n t a n e a t room t e m p e r a t u r e . The d a t a t h u s o b t a i n e d h a v e b e e n u s e d t o c a l c u l a t e t h e e x p e c t e d e q u i l i b r i u m p o s i t i o n f o r n i n e t e e n t r i s u b s t i t u t e d o l e f i n s , a s s u m i n g , a s d i d G a r d n e r a n d M c G r e e r ( 4 5 ) , t h a t i n t e r a c t i o n s w h i c h a r e p r e s e n t i n n i n e 1 , 2 - d i s u b s t i t u t e d o l e f i n s c a n b e c o m b i n e d i n a l i n e a r f r e e e n e r g y s e n s e . I n e l e v e n o f t h e t w e l v e o l e f i n s e q u i l i b r a t e d , t h e a g r e e m e n t b e t w e e n t h e c a l c u l a t e d and t h e e x p e r i m e n t a l v a l u e s h a s b e e n f o u n d t o b e g o o d . - i i i -T h e e q u i l i b r i u m d a t a f o r s o m e u n s a t u r a t e d n i t r i l e s a n d u n s a t u r a t e d e s t e r s h a v e b e e n a c h i e v e d c a t a l y t i c a l l y ( B r 2 / C C l ^ ) o r t h e r m a l l y . F o r t h e s e o l e f i n s i t h a s b e e n f o u n d t h a t t h e i r e q u i l i b r i u m p o s i t i o n s m a y b e a t t r i b u t e d t o m a n y f a c t o r s . T h e s e f a c t o r s a r e : I ) a s t e r i c e f f e c t i n v o l v i n g o n l y t r a d i t i o n a l s t e r i c i n t e r a c t i o n s b e t w e e n b u l k i e r g r o u p s ; I I ) a n a t t r a c t i v e n o n b o n d e d i n t e r a c t i o n w h i c h i s p r e s e n t b e t w e e n m a n y g r o u p s ; I I I ) a p o l a r r e p u l - s i v e t e r m i n v o l v i n g e l e c t r o s t a t i c r e p u l s i v e i n t e r a c t i o n s b e t w e e n p o l a r g r o u p s ; a n d I V ) a c o n . j u g a t i v e s t a b i l i z a t i o n  e f f e c t w h e r e c o n j u g a t i v e s t a b i l i z a t i o n b y r e s o n a n c e i s g r e a t e r i n t r a n s i s o m e r t h a n i n c i s i s o m e r , w h e n t h e c a r -b o n y l g r o u p i s m a r k e d l y s e n s i t i v e t o s t e r i c e f f e c t s o f c i s s u b s t i t u e n t s . I t h a s b e e n o b s e r v e d i n t h i s s t u d y t h a t s t e r i c f a c t o r s a r e d o m i n a n t f o r e q u i l i b r i a o f t h e u n s a t u r a t e d e s t e r s a n d p o l a r e f f e c t s m a i n l y a r e d o m i n a n t f o r e q u i l i -b r i a o f t h e n i t r i l e s . - i v -TABLE OF CONTENTS Page T I T L E PAGE i ABSTRACT i i TABLE OF CONTENTS i v L I S T OF TABLES v i L I S T OF FIGURES v i i i ACKNOWLEDGEMENTS i x INTRODUCTION 1 D e t e r m i n a t i o n o f c o n f i g u r a t i o n 2 T h e r m o d y n a m i c s o f c i s - t r a n s e q u i l i b r a t i o n s .... 6 F a c t o r s a f f e c t i n g t h e s t a b i l i t y o f g e o m e t r i c a l i s o m e r s 7 M e t h o d s o f e s t a b l i s h i n g a n d m e a s u r i n g e q u i -l i b r i a 15 E x a m p l e s o f known e q u i l i b r i a 17 F r e e e n e r g y a d d i t i v i t y f o r o l e f i n p a i r s Zk OBJECT OF THE PRESENT WORK 27 RESULTS AND DISCUSSION 2 9 P r e p a r a t i o n o f E a n d Z h a l o e t h y l e n e s 29 P r e p a r a t i o n o f E a n d Z n i t r i l e s '. Jk P r e p a r a t i o n o f u n s a t u r a t e d e s t e r s 51 E q u i l i b r a t i o n o f o l e f i n s o f T a b l e s 5 and 7 • • • • 56 E q u i l i b r a t i o n o f u n s a t u r a t e d e s t e r s 61 - V -Page D i p o l e moments * • 61 DISCUSSION 68 F a c t o r s a f f e c t i n g e q u i l i b r i u m p o s i t i o n s 69 E q u i l i b r i u m p o s i t i o n s o f some u n s a t u r a t e d e s t e r s 77 A s s i g n m e n t o f c o n f i g u r a t i o n . •• 86 F r e e e n e r g y a d d i t i v i t y 96 EXPERIMENTAL 106 G e n e r a l s t a t e m e n t • 106 H a l o e t h y l e n e s a n d n i t r i l e s 0 . . . . . . . . 110 U n s a t u r a t e d e s t e r s • 131 S o l v e n t b l a n k s 1^0 C o n c e n t r a t i o n e f f e c t s 1^0 REFERENCES 1^2 APPENDIX 1 1 " I n s t a n t " s t a n d a r d d e v i a t i o n s 1^8 APPENDIX II.* C a l c u l a t i o n o f d i p o l e moments 153 - v i LIST OF TABLES Table Page 1 Conversion of isomer % to free energy-differences at 2 5 °C 0 . . 8 2 Solvent e f f e c t s on the equilibrium of ol e f i n s at 2 5 °C 1 3 3 Percent composition of E isomer at equilibrium (41) 20 4 Equilibrium positions f o r some o l e f i n s .... 26 5 Haloethylenes prepared for e q u i l i b r a t i o n .. 3 0 6 V.p.c. data and b o i l i n g points of haloethylenes 31 7 N i t r i l e s prepared f o r equilibrium studies . 3 5 8 V.p.c. data f o r unsaturated n i t r i l e s 3 7 9 Chemical s h i f t s and coupling constants f o r the n i t r i l e s of Table 7 < > . . . . 3 9 10 Unsaturated esters prepared f o r e q u i l i b r i a 5 1 1 1 Chemical s h i f t s and coupling constants f o r the esters ..»............. • 5 2 12 Equilibrium positions found f o r d i - and t r i s u b s t i t u t e d ethylenes 5 8 1 3 Equilibrium positions f o r unsaturated esters 62 14 Dipole moments of o l e f i n s 6 3 - v i i -Table Page 15 Pyrolysis of E-$6 at 210°C 81 16 Change i n equilibrium p o s i t i o n (expressed i n % E at equilibrium) as predicted from dipole moments and compared with those observed » 91 17 "Instant" standard deviations 1^9 18 Group moments • 15^ - v i i i -LIST OF FIGURES Figure Page 1 van der V/aals curve 10 2 Reaction diagram f o r A^=±B i n s o l v e n t s 1 and 2 Ik 3 R a d i c a l - c a t a l y z e d mechanism of o l e f i n i s o m e r i z a t i o n 16 k A c i d - c a t a l y z e d i s o m e r i z a t i o n of o l e f i n s ... 16 5 An example of f r e e energy a d d i t i v i t y i n o l e f i n s 2k 6 E q u i l i b r i u m p o s i t i o n s found ( i n parentheses) and c a l c u l a t e d f o r t r i s u b s t i t u t e d o l e f i n s a t 25 °C 99 7 C a l c u l a t e d e q u i l i b r i u m p o s i t i o n s f o r some o l e f i n s 10^ - i x -V ACKNOWLEDGEMENTS I w i s h t o e x p r e s s my s i n c e r e t h a n k s a n d a p p r e c i -a t i o n t o P r o f e s s o r D o n a l d E. M c G r e e r f o r h i s c o n s t a n t i n t e r e s t a n d g u i d a n c e t h r o u g h o u t t h e c o u r s e o f t h i s r e -s e a r c h p r o j e c t a n d d u r i n g t h e p r e p a r a t i o n o f t h i s manu-s c r i p t • I am most g r a t e f u l t o M i s s T. S c h i a v o n f o r h e r e x t r e m e p a t i e n c e a n d d i l i g e n c e i n t h e d i f f i c u l t t a s k o f l e t t e r i n g i n t h e f o r m u l a e a n d t y p i n g o f t h i s t h e s i s . INTRODUCTION The v a n ' t H o f f ( 1 ) m o d e l i n d i c a t e d t h e e x i s t e n c e o f two s t a b l e p l a n a r a r r a y s f o r t h e e t h y l e n e m o l e c u l e , B a e y e r ( 2 ) d e s i g n a t e d t h e s e a s c i s - t r a n s i s o m e r s . The p r e f i x e s c i s a n d t r a n s d e s c r i b e d t h e s i t u a t i o n s i n v o l v i n g two e q u a l g r o u p s o n t h e same s i d e o r o p p o s i t e s i d e s o f t h e d o u b l e b o n d , r e s p e c t i v e l y . The c o n f i g u r a t i o n a l d e s c r i p t o r s c i s a n d t r a n s , t h o u g h e x t e n s i v e l y u s e d i n l i t e r a t u r e , h a v e r e s u l t e d i n a g r e a t d e a l o f a m b i g u i t y b e c a u s e t h e s e h a v e n o t b e e n d e f i n e d a c c o r d i n g t o a n y g e n e r a l l y a c c e p t e d u n i v e r s a l l y a p p l i c a b l e r u l e s (3*4). R e c e n t l y , a new s e t o f c o n f i g -u r a t i o n a l d e s c r i p t o r s Z a n d E h a v e b e e n s u g g e s t e d (3»5) b a s e d o n t h e s e q u e n c e r u l e s o f C a h n , I n g o l d , a n d P r e l o g (6) w h i c h p e r m i t u n a m b i g u o u s d e s c r i p t i o n o f d o u b l e b o n d s t e r e o i s o m e r i s m i n a l l c a s e s . T h a t c o n f i g u r a t i o n i n w h i c h t h e t w o g r o u p s o f h i g h e s t p r i o r i t y a r e on t h e same s i d e o f t h e d o u b l e b o n d i s a s s i g n e d t h e s t e r e o c h e m i c a l d e s c r i p t o r Z. ( f r o m t h e German zusammen); t h a t c o n f i g -u r a t i o n i n w h i c h t h e s e g r o u p s a r e on o p p o s i t e s i d e s i s a s s i g n e d t h e s t e r e o c h e m i c a l d e s c r i p t o r E ( f r o m t h e German e n t g e g e n ) . The p r i o r i t y f o r t h e s e q u e n c e r u l e i s e s t a b -l i s h e d b y a r r a n g i n g atoms o r g r o u p s i n a n o r d e r o f p r e f -e r e n c e w here t h e a t o m w i t h t h e h i g h e s t a t o m i c number i s p r e f e r r e d o v e r t h e o t h e r a t o m ( e . g . B r i s p r e f e r r e d t o C l a n d C H 3 C H 2 i s p r e f e r r e d t o C H 3 ) . H o w e v e r , t h e c l a s s i c a l c i s a n d t r a n s t e r m s w i l l be u s e d t o d e s i g n a t e 1 , 2 - i n t e r -a c t i o n s , e i t h e r on same s i d e ( c i s ) o r on o p p o s i t e s i d e s ( t r a n s ) o f t h e d o u b l e b o n d . The d e s i g n a t i o n s Z and E s h a l l A — ^ c i s t r a n s be u s e d i n names o f c o m p o u n d s . D e t e r m i n a t i o n o f C o n f i g u r a t i o n A s a r e s u l t o f t h e d i f f e r e n c e s i n s h a p e a n d s y m m e t r y b e t w e e n c o r r e s p o n d i n g c i s a n d t r a n s i s o m e r s t h e r e a r e d i f -f e r e n c e s i n a l a r g e number o f p h y s i c a l a n d c h e m i c a l c h a r a c -t e r i s t i c s . T h e r e f o r e , b o t h p h y s i c a l a n d c h e m i c a l m e t h o d s may be u s e d t o d e t e r m i n e c o n f i g u r a t i o n o f u n s a t u r a t e d s y s t e m s . The l a b o r i o u s c h e m i c a l m e t h o d s ( 7 ) o f e a r l i e r y e a r s h a v e b e e n a l m o s t e l i m i n a t e d b y t h e m o d e r n i n s t r u m e n t -a t i o n a n d s p e c t r o s c o p i c t e c h n i q u e s . - 3 -I n f r a r e d ( i . r . ) a n d n u c l e a r m a g n e t i c r e s o n a n c e ( n . m . r . ) a r e t h e m o s t w i d e l y e m p l o y e d p h y s i c a l m e t h o d s b y t h e o r g a n i c r e s e a r c h c h e m i s t s . A l s o e m p l o y e d , b u t l e s s commonly, a r e t h e d i p o l e moment m e a s u r e m e n t s ( 8 ) and u l t r a v i o l e t s p e c t r o s c o p i c ( 9 ) t e c h n i q u e s . D i f f e r e n c e s i n t h e i n f r a r e d s p e c t r a o f 1 , 2 - d i -s u b s t i t u t e d ( 1 0 ) i s o m e r p a i r s a r e f o u n d i n t h e 1 6 5 0 cm~* r e g i o n , C=C s t r e t c h i n g v i b r a t i o n . F o r a m o l e c u l a r v i b r a t i o n t o g i v e r i s e t o i n f r a r e d a b s o r p t i o n , i t m u s t p r o d u c e a c h a n g e i n t h e d i p o l e moment o f t h e m o l e c u l e . A s a c o n s e q u e n c e o f t h i s , s y m m e t r i c a l l y s u b s t i t u t e d t r a n s i s o m e r shows n o d o u b l e b o n d s t r e t c h i n g f r e q u e n c y i n t h e i n f r a r e d , w h e r e a s t h e c i s i s o m e r shows a s t r o n g i n f r a r e d a b s o r p t i o n due t o d o u b l e b o n d s t r e t c h i n g . The d i f -f e r e n c e s a r e l e s s m a r k e d when t h e s u b s t i t u t i o n on t h e e t h y l e n e i s n o t s y m m e t r i c , s o t h a t t h e r e i s a s m a l l d i -p o l e moment e v e n i n t h e t r a n s i s o m e r . T h u s , compounds s u c h a s c r o t o n i c a c i d , E - ( : L ) , show s t r o n g a b s o r p t i o n s . C r U H 3 \ / GOOH E - l _ k -I n i n s t a n c e s w h e r e b o t h c i s a n d t r a n s i s o m e r s p o s s e s s a b s o r p t i o n i n t h e i n f r a r e d s p e c t r a , c i s i s o m e r s a b s o r b a t l o w e r f r e q u e n c y t h a n t h e t r a n s i s o m e r s . C o n j u g a t i o n o f t h e d o u b l e b o n d w i t h a c a r b o n y l o r n i t r i l e u s u a l l y l o w e r s t h e d o u b l e b o n d s t r e t c h i n g f r e q u e n c y b y a b o u t 2 0 - 3 0 c m " 1 . The C=C-H o u t - o f - p l a n e v i b r a t i o n f o r t h e t r a n s i s o m e r s a p p e a r b e t w e e n 8 9 5 - 9 9 5 cm" 1 a n d f o r t h e c i s i s o m e r s b e t w e e n 6 7 5 - 7 3 0 cm" 1 i n t h e i n f r a r e d s p e c t r a . The i n f r a r e d m e t h o d i s o f l e s s g e n e r a l u s e f u l n e s s w i t h t r i s u b s t i t u t e d o l e f i n s . P r o b a b l y t h e m o s t u s e f u l s t r u c t u r a l a s s i g n m e n t o f o l e f i n s i s d e r i v e d f r o m n u c l e a r m a g n e t i c r e s o n a n c e s p e c t r o -s c o p y . The n.m.r. s p e c t r a h a v e made a v a i l a b l e i n f o r -m a t i o n c o n c e r n i n g t h e s t e r e o c h e m i s t r y o f n o t o n l y 1 , 2 - d i s u b -s t i t u t e d b u t a l s o o f t r i - a n d t e t r a s u b s t i t u t e d o l e f i n s ( 1 1 ) . The s t e r e o c h e m i s t r y c a n be d e r i v e d f r o m t h e k n o w l e d g e o f t h e c o u p l i n g c o n s t a n t s a n d t h e s h i e l d i n g o r d e s h i e l d i n g e f f e c t s o f s u b s t i t u e n t s . The s p i n - s p i n c o u p l i n g c o n s t a n t s f o r p r o t o n s h a v e v a l u e s w h i c h a r e t o some e x t e n t c h a r a c t e r i s t i c o f t h e i r s t e r e o c h e m i c a l r e l a t i o n s h i p . T y p i c a l c o u p l i n g c o n s t a n t s ( 1 2 ) a r e 7 - 1 2 Hz f o r p r o t o n s t h a t a r e c i s and I 3 - I 8 Hz f o r - 5 -trans protons. In a l l cases i t has been observed that the trans coupling constant was greater than the cis coupling constant for a given pair of isomers. Diamagnetic anisotropic deshielding effects of various groups yield quite useful information as f i r s t realized by Jackman and Wiley ( 1 3 ) . Working with (!*{]>-unsaturated esters, they observed that a substituent Pto a carbomethoxy group (each attached to one end of a double bond) appeared at a lower f i e l d strength when oriented cis to the ester group. Later observations on n.m.r. by Fraser (lk) and McGreer etal ( 1 5 , 1 6 ) were found to be i n agreement with the findings of Jackman and Wiley. Other groups such as acids, amides, acyl halides, and n i t r i l e s have the same effect on the cis oriented substituent. Pascual etal (17»18,19) and Tobey (20) have derived shielding parameters for various substituents. They have defined these substituent constants as the average shi f t of a vinyl proton resulting from the intro-duction of a substituent i n the cis, trans, or geminal positions, respectively. They indicate that chemical shifts may be estimated by empirical additive shielding parameters. The usefulness of such an additive method is - 6 -obvious p a r t i c u l a r l y i n cases where a d i s t i n c t i o n between the isomers i s being made. The authors ( 1 9 ) also point out some discrepancies between the calculated and the experimental values. They have att r i b u t e d these to various s t r u c t u r a l features such as conjugation or conformation of the substituent involved. Thermodynamics of ci s - t r a n s E q u i l i b r a t i o n s I t i s perhaps desirable at t h i s point to consider some of the thermodynamic properties of the equilibrium state to understand some of the factors a f f e c t i n g i t . For the isomeric equilibrium A B the thermodynamic equilibrium constant K i s given by K M where [A] and [ B ] are the equilibrium concentrations of A and B, r e s p e c t i v e l y . (Ideally, K should be expressed as the equilibrium p a r t i a l pressure r a t i o or as the a c t i v i t y r a t i o ) . The standard free energy change i s given by the following expression ( 2 1 , 2 2 , 2 3 ) AG ° = -RTlnK The relative thermodynamic s t a b i l i t y of geometrical isomers can be deduced from free energy of formation where-ever i t i s known. If i t i s not available, then the two isomers can be equilibrated and from the position of equi-librium, their free energy difference can be calculated directly. Table 1 provides the conversion of isomer per-centage to free energy differences and vice versa. The value of AG° i s dependent upon two factors, AH°, the enthalpy difference between the two isomers* andAS°9 the entropy difference between the two isomers. A G° = A H° - TAS° The free energy term i s temperature dependent. The equilibrium position w i l l change with temperature i f <AS° •£ o. Such differences w i l l presumably be relatively unimportant for olefins with spherically symmetrical groups such as halogens or n i t r i l e s , but considerably more important for unsymmetrical groups (2*0. Factors Affecting the S t a b i l i t y of Geometrical Isomers The equilibrium position i n cis-trans olefin pairs may be affected by many factors. The bonding interactions between cis substituents, when present, usually dominate most equil i b r i a . These bonding interactions include an - .8 -Table 1 Conversion of isomer % t o f r e e energy d i f f e r e n c e s at 25 °C % R a t i o -Acfdccal) % R a t i o -Acfdccal) 50 1.00 0 75 3.00 0.651 51 1 . 0 4 0 . 0 2 4 76 3.17 O.683 52 1.08 0 . 0 4 7 77 3 . 3 5 0.715 5 3 1.13 0.071 78 3 . 5 5 0.7^9 5 * 1.17 0.085 79 3.76 0.785 5 5 1.22 0.119 8 0 4.00 0 . 8 2 1 56 1.27 0 . 1 4 3 8 1 4 . 2 6 0.859 5 7 1.33 0.167 8 2 4.56 0.899 58 1.38 0.191 83 4.88 0.939 59 1.44 0.216 8 4 5.25 0.982 60 1.50 0 . 2 4 0 85 5.67 1.027 6 1 1.56 0.265 86 6 . 1 4 1.075 6 2 I.63 0.290 87 6.69 1.126 63 1.70 0.315 88 7 . 3 3 1 . 1 8 0 6 4 1.78 0 . 3 4 1 89 8.09 1.238 6 5 1.86 0.367 90 9.00 1.301 66 1.9^ 0.393 91 10.10 1.37 67 2.03 0.419 92 11.50 1.45 68 2.13 0 . 4 4 6 93 13.30 1.53 69 2.23 0 . 4 7 4 94 15.70 L63 70 2 . 3 3 0.502 95 19.00 1.74 71 2.45 0.530 96 24.00 1.88 72 2 . 5 7 0 . 5 5 9 97 32.33 2.06 7 3 2.70 0.589 98 49.00 2.30 7^  2.85 0.619 99 99.00 2.72 - 9 -e x t r e m e c a s e o f a n h y d r i d e f o r m a t i o n a n d i n t e r n a l h y d r o g e n b o n d i n g . E t h y l 3 - a m i n o c r o t o n a t e (2) d e m o n s t r a t e s t h e l a t t e r c a s e i n w h i c h t h e Z i s o m e r d o m i n a t e s t h e e q u i l i b r i u m (25). C H 3 N /* C H 3 N / C 0 2 C 2 H 5 / \ / \ I II 5 2 H -0 Z-2 E-2 T h e s e b o n d i n g i n t e r a c t i o n s , b e c a u s e o f t h e i r d o m i n a n c e o f t h e e q u i l i b r i a , d o n o t a l l o w i n v e s t i g a t i o n o f o t h e r e f f e c t s w h i c h m a y i n f l u e n c e t h e e q u i l i b r i u m , b u t t o a m u c h l e s s e r d e g r e e s T r a d i t i o n a l l y , s t e r i c f a c t o r s h a v e b e e n e m p h a s i z e d i n d e a l i n g w i t h c i s - t r a n s s t a b i l i t i e s . T h e r e a s o n m a y b e t h a t t h e s t a b i l i t i e s o f h y d r o c a r b o n o l e f i n s , s t i l b e n e , d i e t h y l m a l e a t e a n d f u m a r a t e , a n d t h e c i n n a m a t e e s t e r s (26) w e r e a m o n g t h e f i r s t c i s - t r a n s o l e f i n p a i r s t o b e s t u d i e d . A n d i n a l l t h e s e c a s e s s t e r i c f a c t o r s d o m i n a t e 0 A n u m b e r o f 1 , 2 - d i s u b s t i t u t e d o l e f i n s h a v e b e e n o b s e r v e d t o b e m o r e s t a b l e i n t h e c i s f o r m t h a n i n t h e - 10 -t r a n s as observed by V i e h e ( 2 7 , 2 8 , 2 9 ) . The s t a b i l i z a t i o n was t h o u g h t t o be t h e r e s u l t o f a van d e r Waals o r e l e c t r o -s t a t i c a t t r a c t i o n between t h e many groups i n v o l v e d . A van d e r Waals f u n c t i o n i s , i n t h e o r y , composed o f two p a r t s . A t l o n g e r d i s t a n c e s ( r ) t h e r e e x i s t s an a t t r a c t i v e f o r c e between two atoms w h i c h i s p r o p o r t i o n a l t o ( 1 / r ^ ) . T h i s f o r c e may be termed an i n d u c e d d i p o l e -i n d u c e d d i p o l e i n t e r a c t i o n , a London f o r c e o r a d i s p e r s i o n f o r c e . A s h o r t range r e p u l s i v e term, c a l l e d t h e van d e r Waals r e p u l s i v e i n t e r a c t i o n , c o m p r i s e s t h e second p a r t o f t h e van d e r Waals f u n c t i o n . T h i s f o r c e i s p r o p o r t i o n a l t o (1/r ) and i t a r i s e s from t h e r e p u l s i o n between n u c l e i and e l e c t r o n s o f t h e atoms c o n c e r n e d . S i n c e t h e r e p u l s i v e f o r c e d e v e l o p s q u i t e a b r u p t l y and t h e a t t r a c t i v e f o r c e i n c r e a s e s i n i m p o r t a n c e more E r F i g u r e 1. van d e r Waals c u r v e - 11 -g r a d u a l l y , t h e c o m b i n a t i o n o f t h e t w o f o r c e s l e a d s t o t h e f a m i l i a r v a n d e r W a a l s c u r v e ( F i g u r e 1). T h u s , i f t h e d i s t a n c e b e t w e e n c i s s u b s t i t u e n t s i s j u s t o u t s i d e t h e c o m b i n e d v a n d e r W a a l s r a d i i , t h e n a n a t t r a c t i v e f o r c e w o u l d r e s u l t . F o r e t h y l e n e s , t h e d i s t a n c e b e t w e e n t h e i n t e r a c t i n g c i s g r o u p s o r atoms w o u l d be a f u n c t i o n o f t h e s i z e o f t h e g r o u p s o r a t o m s , t h e b o n d a n g l e s w i t h t h e e t h y l e n e c a r b o n s , a n d t h e b o n d l e n g t h s f r o m t h e d o u b l e b o n d c a r b o n t o t h e g r o u p s o r a toms i n q u e s t i o n . D i p o l a r i n t e r a c t i o n s , i n v o l v i n g e i t h e r e l e c t r o -s t a t i c r e p u l s i o n s o r a t t r a c t i o n s may be a f a c t o r i n v o l v e d i n i s o m e r s t a b i l i t y . The p o s s i b i l i t y o f d i p o l a r i n t e r -a c t i o n s a r i s e s when p o l a r g r o u p s o r e l e c t r o n e g a t i v e a t o m s s u c h a s h a l o g e n s , n i t r i l e s , c a r b o n y l and c a r b o x y l , e t c . a r e on one c a r b o n and s i m i l a r g r o u p s a r e p r e s e n t on t h e o t h e r . I n a d d i t i o n t o d i p o l e - d i p o l e i n t e r a c t i o n s , t h e r e i s a l s o a p o s s i b i l i t y o f d i p o l e - i n d u c e d d i p o l e i n t e r a c t i o n s i n w h i c h one g r o u p i s p o l a r a n d t h e o t h e r g r o u p i s p o l a r -i z a b l e . A n e f f e c t w h i c h h a s n o t b e e n e m p h a s i z e d i n c i s - t r a n s e q u i l i b r i a , b u t h a s b e e n c o n s i d e r e d i n o t h e r e q u i l i b r i a (30) i s t h a t o f s o l v e n t s t a b i l i z a t i o n o f one i s o m e r o v e r t h e o t h e r . The l i t e r a t u r e i s s c a n t y o f modern i l l u s t r a t i o n o f - 12 -t h e r e l a t i o n s h i p b e t w e e n s o l v e n t e f f e c t s on e q u i l i b r i u m c o n s t a n t s a n d s o l v e n t s t a b i l i z a t i o n o f t h e s u b s t a n c e s i n v o l v e d . I n t u i t i v e l y , t h e more p o l a r i s o m e r s h o u l d be s t a b i l i z e d i n a more p o l a r s o l v e n t ? i n f a c t , t h i s p o l a r s o l v e n t may be t h e n e a t s o l u t i o n o f i s o m e r s i t s e l f i n w h i c h t h e e q u i l i b r i u m i s e s t a b l i s h e d . A n e x a m p l e o f t h i s k i n d o f e f f e c t i s d e s c r i b e d b y Wood and D i c k i n s o n (31) who n o t e d t h a t t h e c i s - t r a n s e q u i l i b r i u m c o n s t a n t v a r i e d s l i g h t l y b e t w e e n t h r e e n o n -p o l a r s o l v e n t s a n d t h e n e a t s o l u t i o n . M c M u l l e n a n d S t i r l i n g (32) a l s o d e s c r i b e d s o l v e n t e f f e c t s on t h e c i s - t r a n s e q u i l i b r i u m o f v a r i o u s e n a m i n e s . The d i f f e r e n c e s i n e q u i l i b r i u m i n p o l a r a n d n o n - p o l a r s o l v e n t s w e r e e x -p l a i n e d a s a b a l a n c e b e t w e e n i n t e r - a n d i n t r a m o l e c u l a r h y d r o g e n b o n d i n g . B.D. P a ge (33) o f t h i s l a b o r a t o r y e x a m i n e d t h e e q u i l i b r i u m p o s i t i o n s f o r f i v e compounds i n a v a r i e t y o f s o l v e n t s . The compounds s t u d i e d w e r e c r o t o n o n i t r i l e (_3_), 3 - f c r o m o a c r y l o n i t r i l e ( 4 ) , 2 - b r o m o c r o t o n o n i t r i l e ( £ ) , 1 , 2 - d i b r o m o e t h y l e n e ( 6 ) , a n d 1 , 2 - d i c h l o r o e t h y l e n e (£)• The m e a s u r e d v a l u e s o f t h e s e compounds a l o n g w i t h t h e i r d i p o l e moments a p p e a r i n T a b l e 2 . The e q u i l i b r i u m p o s i -t i o n i s g i v e n a s t h e p e r c e n t o f t h e more d o m i n a n t i s o m e r Table 2. Solvent e f f e c t s on the e q u i l i b r i u m of some o l e f i n s at 25 °G CH. Br ^C==CHCN ^ ( ! ^C=CHCN H 3 H ^ H Br C l =CBrCN ^C=CHBr \ c = C H C l H" 6 H ^ C = C B r CDipole moment of Z-form (D) 4.08 4.70a 3.88a 1.35 1.91 Dipole moment of E-form (D) ^.53 2.48a 3 . 5 1 a 0.00 0.00 C a l c u l a t e d d i p o l e moment of e q u i l i b r i u m mixture f o r the neat sample (D) *.3 4.0 3.8 0.68 0.96 Em (kcal/mol) Solvent (25°C)(34) Neat l i q u i d b Pentane 3 0 . 9 Carbon t e t r a c h l o r i d e 3 2 . 5 Benzene 3 .^5 Ether 3 .^6 B e n z o n i t r i l e 42.0 A c e t o n i t r i l e 46.0 56 Z 61 Z 61 Z 57 Z 59 Z 54 Z 56 Z 68 Z 51 Z 55 Z 65 Z 68 Z 69 Z 6? Z 69 Z 6 9 Z 69 Z 61 Z 5 2 Z 63 Z 6 0 Z 66 Z 7 2 Z 81 Z 74 Z 80 Z 84 Z 87 Z a C a l c u l a t e d d i p o l e moments. b This i s the value f o r n-hexane. - 12+ -w h i c h i s i d e n t i f i e d b y Z o r E . I t i s s e e n i n T a b l e 2 t h a t t h e p r o p o r t i o n o f t h e more p o l a r i s o m e r i s e n h a n c e d i n a l l c a s e s i n t h e more p o l a r s o l v e n t . The i n t e r p r e t a -t i o n i s t h a t t h e more p o l a r s o l v e n t b r i n g s a b o u t a g r e a t e r l o w e r i n g o f t h e e l e c t r o s t a t i c e n e r g y o f t h e i s o m e r w i t h l a r g e r d i p o l e moment a n d h e n c e g e t t i n g s t a b i l i z e d i n t h e more p o l a r s o l v e n t . L e f f l e r a n d G r u n w a l d ( 2 3 ) h a v e d e s c r i b e d t h e t h e r m o d y n a m i c b a s i s o f s o l v e n t s t a b i l i z a t i o n . F i g u r e 2 shows t h e s t a n d a r d p a r t i a l m o l a r f r e e e n e r g i e s ( G ? ) o f a r e a c t i n g s y s t e m c o n s i s t i n g o f a s i m p l e i s o m e r i z a t i o n G° A ^ B F i g u r e 2 . R e a c t i o n d i a g r a m f o r A ^ B i n s o l v e n t s 1 a n d 2 . - 1 5 -r e a c t i o n , A^±B, i n t w o s o l v e n t s , d e s i g n a t e d 1 a n d 2 . 8 i s t e r m e d t h e s o l v e n t s t a b i l i z a t i o n o p e r a t o r , m F i g u r e 2 i n t e r p r e t s t h e p r e f e r e n t i a l s t a b i l i z a t i o n o f one i s o m e r b y a p a r t i c u l a r s o l v e n t 2 w i t h r e s p e c t t o a r e f e r e n c e s o l v e n t 1 . M e t h o d s o f E s t a b l i s h i n g a n d M e a s u r i n g E q u i l i b r i a A p u r e g e o m e t r i c a l i s o m e r c a n be c o n v e r t e d i n t o a n e q u i l i b r i u m m i x t u r e w i t h i t s s t e r e o i s o m e r i n a v a r i e t y o f w a y s . The m o s t s t r a i g h t f o r w a r d , a l t h o u g h n o t n e c e s -s a r i l y t h e b e s t , m e t h o d o f i n t e r c o n v e r s i o n i s b y h e a t i n g . The e q u i l i b r i u m e s t a b l i s h e d t h i s way, h o w e v e r , d o e s n o t n e c e s s a r i l y c o r r e s p o n d t o t h e e q u i l i b r i u m e s t a b l i s h e d a t l o w t e m p e r a t u r e s , a s t h e f r e e e n e r g y d i f f e r e n c e b e t w e e n i s o m e r s i s t e m p e r a t u r e d e p e n d e n t . The u s u a l m e t h o d o f e f f e c t i n g t h e e q u i l i b r i u m i s b y c a t a l y s i s . Among t h e many c a t a l y t i c a g e n t s u s e d a r e t h e f r e e r a d i c a l c a t a l y s t s , s u c h a s h a l o g e n s i n t h e p r e s e n c e o f l i g h t ; a c i d s , p - t o l u e n e s u l f o n i c a c i d a n d b o r o n t r i f l u o r i d e , a n d h y d r o g e n a t i o n - d e h y d r o g e n a t i o n c a t a l y s t s s u c h a s p l a t i n u m a n d s e l e n i u m . Many o t h e r c a t a l y s t s may be e m p l o y e d (35)• The r a d i c a l - c a t a l y z e d m e c h a n i s m p r o b a b l y i n v o l v e s - 16 -a d d i t i o n t o the double bond t o form an adduct r a d i c a l f o l l o w e d by r o t a t i o n and departure of the r a d i c a l r e s u l t -i n g i n the geometrical isomer of the s t a r t i n g m a t e r i a l . R R H + X ^ H R + X Figure 3» R a d i c a l - c a t a l y z e d mechanism of o l e f i n i s o m e r i z a t i o n . A c i d - c a t a l y z e d i s o m e r i z a t i o n i n v o l v e s p r o t o n a t i o n f o l l o w e d by the formation of a carbonium i o n through which i s o m e r i z a t i o n occurs ( 3 6 ) . S 2 5 + _ i f _ H " H C „ H „ C -5 ° 1 ! - O C 2 H 5 .8 - 0 C 2 H 5 + - H H C - 0 C 2 H 5 < > H ; - O C 2 H 5 OH H v S f / C ~ 0 C 2 H 5 < > H C o H ^ O - C i5o-g-9H H C - O C o H * H C - 0 C 2 H 5 0 -> \ OH H C - O C - H -2 5 C 2 H 5 0 - g H Figure 4. A c i d - c a t a l y z e d i s o m e r i z a t i o n of o l e f i n s . - 1 7 -I d e a l l y , a n e q u i l i b r i u m s h o u l d b e a p p r o a c h e d f r o m b o t h s i d e s . H o w e v e r , i n s o m e c a s e s e q u i l i b r i u m c a n b e a c h i e v e d f r o m o n e s i d e o n l y . I n t h i s i n s t a n c e i t i s n e c e s s a r y t o d e t e r m i n e t h a t t h e e q u i l i b r i u m s t a t e h a s b e e n r e a c h e d b y g r a p h i c a l l y p l o t t i n g t h e a p p r o a c h t o t h e e q u i l i b r i u m v a l u e a s y m p t o t i c a l l y . T h e e q u i l i b r i u m p o s i t i o n , o n c e a c h i e v e d , c a n b e e s t i m a t e d b y a v a r i e t y o f m e t h o d s . P r o b a b l y t h e m o s t a c c u r a t e i s t h e v a p o r p h a s e c h r o m a t o g r a p h y m e t h o d , p r o v i d e d t h e i s o m e r s c a n b e s e p a r a t e d r e a d i l y w i t h o u t i s o m e r i z a t i o n o r d e c o m p o s i t i o n a t t h e v . p . c . t e m p e r a -t u r e . T h e n u c l e a r m a g n e t i c r e s o n a n c e s p e c t r o s c o p i c m e t h o d i s a l s o f a i r l y a c c u r a t e a n d t h e e q u i l i b r i u m p o s i t i o n c a n b e e a s i l y m e a s u r e d . S o m e o t h e r m e t h o d s t h a t h a v e b e e n u s e d a r e i n f r a r e d s p e c t r o s c o p y , d i p o l e m o m e n t , a n d r e f r a c t i v e i n d e x m e a s u r e m e n t s . E x a m p l e s o f K n o w n E q u i l i b r i a T h e l i t e r a t u r e g i v e s m a n y e x a m p l e s o f p r e p a r a t i o n o f a g r e a t n u m b e r o f c i s - t r a n s o l e f i n p a i r s . A f e w k n o w n e x a m p l e s o f e s t e r s a n d n i t r i l e s , w h e r e t h e p o s i t i o n o f e q u i l i b r i u m w a s d i s c u s s e d , f o l l o w . M e t h y l 2 - m e t h y l - 2 - b u t e n o a t e (8) w a s e q u i l i -- 18 -brated at 250°C by McGreer and coworkers ( 3 7 ) . They found that the E isomer dominated i n the equilibrium by about 86%. H C O o C H . CrU C 0 2 C H ? E-8,86% Z-8,Wo Chiu and McGreer (38) obtained the Z and E isomers of methyl 2,4-dimethyl-2-pentenoate (£)• In t h i s case as well, the E isomer was the more stable one by Qk%. C02CH3 (CH 3) 2CH^ ^C0 2CH 3 (CH 3) 2CH / / ^CH 3 / \n E-2,84?S Z - £ , 1 6 # Y.Y. Wigfield (39) of t h i s laboratory reported the following equilibrium positions f o r methyl 3-bromo-methacrylate (10) and methyl 3-methoxymethacrylate (11). H C0 2CH 3 Br C0 2CH 3 H C0 2CH ? CH.O fiO-CH^ / \ / \ / \ J \ Br CH 3 H CH 3 CH-jO CH 3 H uri E-10^>99?S Z -10 ,<1# E - l l , > 9 9 . 8 ^ Z-U,<C0.2?g - 19 -Interestingly enough, a l l the compounds, 8 , 2 , 10, » II. » a r e ^ore stable in the E form despite the varying steric requirements of the substi-tuents at C - 3 • Purukawa etal (40) investigated the geometrical isomerism of propenyl ethers. They observed that the bulkier alkyl groups such as isopropyl and t-butyl unexpectedly stabilized the Z isomer relative to the E isomer. They f e l t that these facts were probably due C H o 0 C H 0 C j . r U O C r U i-PrO C P U t-BuO C H Q / \ 7 \ / \ " / \ H H H H H H H H Z-12,49?5 Z-13.,58^ Z-14,73^ Z-1^, 77% to the geometrical structure of the molecule and rota-2 tional isomerism around the sp C-—0 bond. Recently Gardner and McGreer (41) prepared a series of a» | 3 ~ U N S A ' T U R A ' T E D esters and n i t r i l e s substi-tuted at the/^-position with isopropyl or t-butyl groups and at the same carbon with methoxyl, thioethoxyl, d i -ethyl amino, dimethyl amino, chlorine, and hydrogen. The equilibrium positions for the various compounds are listed i n Table 3* - 20 -Table 3 Percent composition of E isomer at Equilibrium (41) CH,0 H. CH,0 H- CH~Q CH, / — \ / — \ / \ t-Bu CN i - P r CN t-Bu CN E-l6,60fo E-12,9Q% E-18,93% CH,0 H CH,0 CH, C l H 3 \ / 3 \ / 3 \ / "t-Bu C0 2C 2H 5 2CH 3 t-Bu 6 0 2 C H 3 E-l£,23# E-20,99# E-21,1.595 CH,0 H C l H C l H i - P r C0 2C 2H 5 C H 3 ~ \ o z R i - p / \ ; o 2 C H 3 E-22,97?g E-22,87.5% E-24,8.5?S CH,v H C,HC H i - P r H 3 \ / 2 5 \ / \ / H ' A J N l / ^OgR / C E-2$,k2% E-26,88?S E-2^, 90% CH H H J 2CH3 E-28,8255 i- P r H H \ / f \ N E-2£,67# t-Bu \ / H CN E-20,98.5^ - 21 -The e x p l a n a t i o n s o f f e r e d t o r e c o n c i l e t h e e q u i l i b r i u m p o s i t i o n s r e p o r t e d i n T a b l e 3 a r e b a s e d on a b a l a n c e o f t h r e e f a c t o r s . The f i r s t f a c t o r t o be c o n s i d e r e d i s s t e r i c i n n a t u r e . Compounds 2j£ t o jlO d e m o n s t r a t e t h e e f f e c t o f o n l y a l k y l g r o u p s on t h e / ^ - c a r b o n . I n a l l c a s e s , e x c e p t w h e r e t h e g r o u p i s t - b u t y l , t h e r e i s a s i g n i f i c a n t amount o f t h e Z i s o m e r . A n o t h e r e f f e c t w h i c h m u s t be c o n s i d e r e d i s t h e s e n s i t i v i t y o f t h e c a r b o n y l compounds t o a c i s s u b s t i t u e n t (42,43). T h i s m a r k e d e f f e c t i s u n d o u b t -e d l y due t o t h e r e q u i r e m e n t t h a t f o r maximum c o n j u -g a t i o n t h e c a r b o n y l m u s t be i n t h e p l a n e o f t h e d o u b l e b o n d a n d i n t h i s f o r m i s v e r y s e n s i t i v e t o c i s s u b -s t i t u e n t s . The c o n t r i b u t i o n o f t h e z w i t t e r f o r m (31) R R 21 21 t o t h e s t a b i l i t y o f c a r b o n y l compounds w o u l d be i n c r e a s e d when a n e l e c t r o n d o n a t i n g (+M e f f e c t ) g r o u p (44) i s a t t a c h e d a t t h e / ^ - p o s i t i o n a n d h e r e a l s o a t r a n s f o r m i s s t r o n g l y f a v o r e d . The e f f e c t i s r e a d i l y o b s e r v e d i n - 22 -compound 20 . I t c a n a l s o "be s e e n i n compound 16 t h a t t h e m e t h o x y l g r o u p , when i n c o n j u g a t i o n , w o u l d he i n t h e p l a n e o f t h e d o u b l e b o n d and t h u s may h a v e a n e f f e c t i v e b u l k g r e a t e r t h a n a t - b u t y l g r o u p , G a r d n e r a n d M c G r e e r a l s o f e e l t h a t , c o u p l e d w i t h s t e r i c e f f e c t s , t h e r e i s a r e p u l s i v e t e r m b e -t w e e n t h e m e t h o x y l a n d t h e n i t r i l e o r e s t e r g r o u p s • T h i s h e l p s e x p l a i n t h e e q u i l i b r i u m p o s i t i o n f o r 1£ • The r e p u l s i v e t e r m b e t w e e n h a l o g e n a n d e s t e r i s i l l u s -t r a t e d b y t h e compound 1.0 a n d compound 2J> w h e r e t h e h a l o g e n s , w h i c h a r e s t e r i c a l l y e x p e c t e d t o be s m a l l e r t h a n t h e m e t h y l g r o u p , p r e f e r t o be t r a n s t o t h e e s t e r g r o u p . The e q u i l i b r i u m p o s i t i o n s o f a number o f 3 - s u b s t i t u t e d m e t h a c r y l o n i t r i l e s h a v e b e e n s t u d i e d b y G a r d n e r a n d M c G r e e r (45), The d a t a i s g i v e n b e l o w . C l C H, B r CH, CH,0 CH, CH.. C H , \ / 3 \ / 3 3 \ / 3 3 \ / 3  3   \ / \ CN H CN K \ N K n ^CN I n t h i s s e r i e s o f compounds, i n c o n t r a s t t o t h e i r o t h e r p a p e r (4l) , i n w h i c h s t e r i c a n d c o n j u g a -- 2 3 -t i v e e f f e c t s were o f c o n s i d e r a b l e i m p o r t a n c e , a n i m p o r -t a n t s t a b i l i z a t i o n due t o v a n d e r W a a l s o r e l e c t r o -s t a t i c a t t r a c t i o n b e t w e e n c i s s u b s t i t u e n t s was s u g g e s t e d . T h i s may a l s o a c c o u n t f o r t h e Z i s o m e r s t a b i l i t y o f compounds 14, 15 « E p i o t i s e t a l (46,4?) h a v e r e c e n t l y r e p o r t e d a s i m p l e m o l e c u l a r o r b i t a l i n t e r p r e t a t i o n f o r t h e g r e a t e r s t a b i l i t y o f c i s i s o m e r s o f 1 , 2 - d i s u b s t i t u t e d h a l o -e t h y l e n e s . T h e y p o i n t o u t a n i n t e r a c t i o n o f t h e l o n e p a i r s o f h a l o g e n s a n d t h e o l e f i n i c b o n d o c c u r i n g i n s u c h c o m p o u n d s . The m a g n i t u d e o f s u c h a n i n t e r a c t i o n i s c o m p a r a b l e i n b o t h c i s a n d t r a n s i s o m e r s . H o w e v e r , o n l y i n c i s d o e s s u c h a n i n t e r a c t i o n l e a d t o " n o n b o n d e d a t t r a c t i o n " a n d n o t i n t r a n s . C o n s e q u e n t l y , t h e t w o h a l o g e n s i n c i s i s o m e r s t e n d t o a t t r a c t e a c h o t h e r a n d , h e n c e , m a k i n g t h e c i s i s o m e r s more s t a b l e t h a n t h e t r a n s . The g r e a t e r s t a b i l i t y o f t h e c i s f o r m s o f 1 - h a l o p r o p e n e s a n d 1 - m e t h o x y p r o p e n e h a v e a l s o b e e n a t t r i b u t e d t o " n o n -b o n d e d a t t r a c t i o n " p r e s e n t i n t h e c i s b u t a b s e n t i n t h e t r a n s (48). A n i n t e r e s t i n g v i e w on c i s - t r a n s s t a b i l i t y h a s b e e n t a k e n b y V i e h e ( 2 9 ) . He r e p o r t s t h a t t h e f o l l o w -i n g c a n be c o n s i d e r e d a s a f i r s t w o r k i n g h y p o t h e s i s t o - 24 -a c c o u n t f o r i s o m e r s t a b i l i t y . "The f o r c e s o f a t t r a c t i o n p r e d o m i n a t e b e t w e e n s u b s t i t u e n t s , p r o v i d e d H-H i n t e r a c t i o n s ( a s i n p u r e h y d r o c a r b o n s ) o r e x t r e m e o v e r c r o w d i n g a r e a b s e n t . " F r e e E n e r g y A d d i t i v i t y f o r O l e f i n P a i r s G a r d n e r a n d M c G r e e r (45) f o u n d e v i d e n c e t o s u g g e s t t h a t , w h e r e s t e r i c e f f e c t s a r e n o t d o m i n a n t , t h e p o s i t i o n o f a c i s - t r a n s e q u i l i b r i u m f o r a t r i -s u b s t i t u t e d o l e f i n c o u l d be e s t i m a t e d b y a d d i n g t h e c o n -t r i b u t i o n o f t h e i s o l a t e d v i c i n a l p a i r s o f s u b s t i t u e n t s . T h e y u s e d t h e f o l l o w i n g e x a m p l e t o i l l u s t r a t e t h e i r s u g g e s t i o n . H H v H CN \ / K * , \ / ,7 \ / \ C l CN C l H H H „ H CH-\ / K b , \ / 3 di \H C / \ i H CN v H C r U \ / J ^ = = ~ \ / / \ ^ / \ C l C H 3 C l CN w h e r e Ka=3l/69 a n d Kb=24.5/75.5 (49). s o Kc=Kb/Ka=42/58. F i g u r e 5» An e x a m p l e o f f r e e e n e r g y a d d i t i v i t y i n o l e f i n s . - 2 5 -T h e i r e s t i m a t e d v a l u e o f 58% f o r t h e E i s o m e r c o m p a r e s f a v o r a b l y w i t h t h e 60% v a l u e a s f o u n d b y t h e m . F i n a l l y , T a b l e 4 l i s t s t h e v a l u e s o f e q u i l i b r i u m p o s i t i o n s o f some c i s - t r a n s o l e f i n p a i r s t h a t h a v e n o t b e e n m e n t i o n e d e a r l i e r , b u t a r e o f i n t e r e s t f o r t h i s s t u d y . - 2 6 -Table 4 Equilibrium Positions f o r Some Olefins Structure % as Temp.°C State or Reference written solvent CH3 Br 68 40 neat 5 0 K 8 0 . 5 24-26 vapor 5 1 CH 3 C l 7 5 3 0 - 3 5 neat 49 H H CH,^ ^CH3 24 2 5 vapor 5 2 */ \ l 2 3 2 5 CH2C1-CH2C1 5 3 C l CN •\ / 69 30-35 neat 49 H H CH 3 Br \ / 83 r . t . neat 54 / \ H CH 3 CH, C l 3\ / \ C H 3 CIU Br 3 \ / / \ Br H CHo C l \ / / \ C l H 80 r . t . pentane 5 5 6 5 r . t . neat 5 6 3 9 4 5 neat ^ 9 OBJECT OF THE PRESENT WORK I t i s s e e n f r o m t h e p r e c e d i n g s e c t i o n t h a t , w h e r e s t e r i c e f f e c t s a r e n o t d o m i n a n t , t h e e q u i l i b r i u m p o s i t i o n o f a t r i s u b s t i t u t e d o l e f i n c o u l d be e s t i m a t e d b y a d d i n g t h e c o n t r i b u t i o n o f t h e i s o l a t e d v i c i n a l p a i r s o f s u b s t i t u e n t s . H o w e v e r , most l i t e r a t u r e v a l u e s o f t h e e q u i l i b r i u m c o n s t a n t s a r e made on n e a t s a m p l e s a t a v a r i e t y o f t e m p e r a t u r e s , t h u s i n t r o d u c i n g u nknown s o l v e n t a n d t e m p e r a t u r e e f f e c t s on d a t a . I t was a l s o shown t h a t s o l v e n t s do a f f e c t t h e p o s i t i o n o f t h e e q u i l i b r i u m , t h e i s o m e r w i t h s m a l l e r d i p o l e moment b e c o m i n g more s t a b l e i n t h e n o n - p o l a r s o l v e n t c o m p a r e d t o t h e i s o m e r w i t h h i g h e r d i p o l e moment. B e c a u s e o f t h e a b o v e o b s e r v a t i o n s i t was d e c i d e d t o ( a ) p r e p a r e 1 , 2 - d i s u b s t i t u t e d a n d t r i s u b s t i t u t e d o l e f i n s w i t h s u b s t i t u e n t s s u c h a s B r , C l , CH^, a n d CN h a v i n g t o p s y m m e t r y and s m a l l e r b u l k , and ( b ) t o s e t up s t a n d a r d c o n d i t i o n s u n d e r w h i c h e q u i l i b r i u m c o n s t a n t s c o u l d be m e a s u r e d t o e x t e n d t h e w o r k o f G a r d n e r a n d M c G r e e r (45) t o f u r t h e r t e s t t h e a d d i t i v i t y r e l a t i o n s h i p . - 28 -To r a t i o n a l i z e t h e p o s i t i o n o f e q u i l i b r i u m i n s t a n d a r d s o l v e n t s c h o s e n f o r t h i s s t u d y i t was d e c i d e d t o i n c l u d e t h e o b s e r v e d a n d / o r c a l c u l a t e d v a l u e s o f t h e d i p o l e moments o f t h e i n d i v i d u a l i s o m e r s . R E S U L T S A N D D I S C U S S I O N P R E P A R A T I O N O F O L E F I N S P r e p a r a t i o n o f E a n d Z i s o m e r s o f H a l o e t h y l e n e s T h e h a l o e t h y l e n e s u s e d f o r e q u i l i b r i u m s t u d i e s w e r e o b t a i n e d a s m i x t u r e s o f E a n d Z i s o m e r s f r o m c o m m e r c i a l s u p p l i e r s o r b y l i t e r a t u r e p r o c e d u r e s , a n d a r e l i s t e d i n T a b l e 5« T h e s e w e r e s e p a r a t e d i n t o i n d i v i d u a l i s o m e r s u s i n g s t a n d a r d c o n d i t i o n s o n a v a p o r p h a s e c h r o m a t o g r a p h e I n T a b l e 6 i s c o m p i l e d t h e v . p . c . d a t a a l o n g w i t h t h e b o i l i n g p o i n t s o f t h e i s o m e r s a t o n e a t m o s p h e r i c p r e s s u r e » T h e v a l u e s i n b r a c k e t s r e p r e s e n t t h e l i t e r a t u r e v a l u e s o f t h e b o i l i n g p o i n t s o f t h e i s o m e r s . 1 - B r o m o p r o p e n e , E - a n d Z - (36) S e p a r a t i o n o f a c o m m e r c i a l s a m p l e o f 1 - b r o m o p r o p e n e b y v . p . c . g a v e E a n d Z i s o m e r s o f t h e s a m e c o m p o u n d 0 1 - C h l o r o p r o p e n e , E- a n d Z - ( 3 7 ) C o m m e r c i a l l y a v a i l a b l e 1 - c h l o r o p r o p e n e w a s s e p a r a t e d b y v . p . c . i n t o E a n d Z i s o m e r s o f t h e t i t l e o l e f i n . - 3 0 -TABLE 5 Haloethylenes Prepared f o r E q u i l i b r a t i o n B A / — \ C H Compound A B C Reference Br H CH 3 A l d r i c h Br CH 3 H «i C l H CH 3 K and K C l CH 3 H Br CH 3 Br This work z-28 Br Br CH 3 t> C l CH 3 C l it C l C l 0H 3 it E-40 Z-40 E-41 Z-41 E-42 CH^ CH 3 CH 3 CH 3 C l CH 3 Br CH 3 C l H Br CH 3 C l CH 3 Br K and K tt tt II This work Z-42 C l Br H tt E-4_3_ CH 3 C l Br it Z-43 CH 3 Br C l ti Table 6 . v.p.c> data and boiling points Helium Retention Compound Column Column Flow rate Times Boiling Point("C) Temp. °C (ml/min) (min) observed (lit.) Reference E-26. 1 1 . 7 6 3 . 8 ( 6 3 ) 5 7 1 0'x 1 / 4 " , 20% DIDP 4 3 8 5 Z-26 9 . 6 5 9 ( 5 8 - . 8 / 7 5 2 ) 5 8 I-1Z 1 1 . 7 3 7 . 5 ( 3 6 . 7 ) 5 9 3 2 8 0 Z-21 9 . 8 3 2 . 5 ( 3 2 ) E - J 8 6 . 2 1 2 5 . 5 ( 1 2 5 ) 5 6 1 2 0'x 3 / 8 " , 3 0 % QF-1 148 1 5 0 Z - ^ 8 " ^ " 8 . 8 1 3 4 - 5 ( 1 3 5 ) E - i i 3 . 0 7 6 ( 7 5 ) 6 0 10«x 1 / 4 " , 20% FFAP 9 0 9 0 6 . 5 9 1 ( 9 2 ) E - 4 0 3 8 . 0 9 5 ( 9 3 . 9 ) 6 1 10»x 1 / 4 " , 20% DIDP 8 8 1 0 0 Z - 4 0 6 . 0 8 6 ( 8 5 . 5 ) E-41 8 . 0 7 1 ( 6 9 - 7 0 ) 5 5 7 8 6 0 Z-41 6 . 0 62.5(62-.2) E - 4 2 4 . 2 7 6 ( 7 5 . 2 - . 4 ) 62 20»x 3 / 8 " , 30% Se - 5 2 1 2 0 6 0 Z-42 7 . 0 84(84.5- .7) 1 - 3 2 -1 , 2 - D i b r o m o p r o p e n e , E - a n d Z- ( 2 8 ) The i s o m e r i c d i b r o m o p r o p e n e s were p r e p a r e d by-t r e a t i n g 1 , 2 , 2 - t r i b r o m o p r o p a n e w i t h s o d i u m p h e n y l a t e a c c o r d i n g t o v a n R i s s e g h e m ' s ( 5 6 ) p r o c e d u r e . The s e p a r -a t i o n o f t h e i s o m e r s f r o m a l c o h o l i c m i x t u r e was a c h i e v e d b y v . p . c . C H , C B r ? - C H ? B r — ^ > ) { + ) ( CoH.OH „ / \ „ / \ 2 5 B r H C H 3 H E - ^ 8 Z-^8 1 , 2 - D i c h l o r o p r o p e n e , E - a n d Z- (39) T r e a t m e n t o f 1 , 2 , 2 - t r i c h l o r o p r o p a n e w i t h one e q u i -v a l e n t amount o f s o d i u m e t h o x i d e i n e t h a n o l (49) f o r 1 5 h o u r s a t 4o°yielded t h e E a n d Z i s o m e r s o f 1 , 2 - d i c h l o r o -p r o p e n e . The i s o m e r s w e r e r e a d i l y s e p a r a t e d b y v . p . c . C H , C l C l C l CoH.ONa A / \ / C H 3 C C 1 2 - C H 2 C 1 2 * > ) = { + C 2 H 5 O H C 1 ' H C H 3 ,H E-22 2 - B r o m o b u t e n e - 2 , E - a n d Z- (40) V . p . c . was e m p l o y e d t o o b t a i n E a n d Z f o r m s o f t h e a b o v e compound f r o m a m i x t u r e o f a c o m m e r c i a l s a m p l e . - 33 -2-Chlorobutene-2, E- and Z- (41) Again, the E and Z forms of the t i t l e compound were obtained by v.p.c. separation of a commercial sample. l-Bromo-2-chloroethylene, E- and Z- (42) Equivalent amounts of 1,2-dibromoethylene and 1,2-dichloroethylene upon heating i n a sealed tube gave, besides the s t a r t i n g materials (S.M.), a 50% y i e l d of the t i t l e compounds (64). The isomeric ethylenes were e a s i l y separated by v.poC. and i d e n t i f i e d by comparison of the b o i l i n g points with those i n the l i t e r a t u r e . Br Br C l C l 0 H Br C l Br \ / , \ / 2 5 0 \ / , \ / / \ + / \ * / \ + / \ H H H H C 1 H H H E-42 Z-42 1-Bromo-l-chloropropene, E- (43) Addition of bromine to 1-chloropropene containing about 85% of i t s E isomer gave 1,2-dibromo-l-chloropropane (66)• Subsequent treatment of 66 with potassium acetate i n a c e t i c acid (63) yielded 35% of the t i t l e compound. H Br KOAc ^ \ / CH0CHBr - CHBrCl * HOAc 3 — / \ CH, C l 66 E-43. - 3^ -1 - B r o m o - l - c h l o r o p r o p e n e , Z- (43_) P h o t o - i n d u c e d b r o m i n e - c a t a l y z e d e q u i l i b r a t i o n o f E - 4 3 p r o v i d e d a m i x t u r e o f E and Z i s o m e r s i n a r a t i o o f 55«^5» T h o u g h i t was d i f f i c u l t t o s e p a r a t e t h e s e i s o m e r s b y v . p . c , a s m a l l amount o f Z was o b t a i n e d b y r e p e a t e d v . p . c . s e p a r a t i o n s . The Z i s o m e r was f o u n d t o be more t h a n 95% p u r e b y n.m.r. H B r - / r r , H B r CHo B r \ / Brg/CCln, \ / + X / / \ 3100A / V / \ CH^ C l J CH3 C l H C l E-4_2 E-4J Z-4J P r e p a r a t i o n o f E a n d Z i s o m e r s o f N i t r i l e s The n i t r i l e s p r e p a r e d f o r e q u i l i b r i u m s t u d i e s a n d f o r t h e p u r p o s e o f t e s t i n g t h e a d d i t i v i t y r e l a t i o n s h i p a r e l i s t e d i n T a b l e 7. M o s t o f t h e s e w e r e p r e p a r e d a c c o r d i n g t o s t a n d a r d m e t h o d s g i v e n i n l i t e r a t u r e . The i n d i v i d u a l i s o m e r s f r o m t h e m i x t u r e s w e r e s e p a r a t e d b y v . p . c , f o r w h i c h t h e d a t a a p p e a r s i n T a b l e 8. The s e p a r a t e d i s o m e r s w e r e m a i n l y i d e n t i f i e d b y t h e n.m.r. s p e c t r o s c o p i c m e t h o d . The c h e m i c a l s h i f t s a n d c o u p l i n g c o n s t a n t s f o r t h e s e i s o m e r s a r e p r e s e n t e d i n T a b l e 9« The c o n f i g u r a t i o n E was a s s i g n e d t o t h e i s o m e r - 35 -T a b l e 7 N i t r i l e s P r e p a r e d f o r E q u i l i b r i u m S t u d i e s B A \ / / \ C CN N i t r i l e A B C R e f e r e n c e C H 3 C l H T h i s w o r k Z - 2 2 CH^ H C l E-12 C H 3 B r H C H 3 H B r •• CH3 OCH 3 H C H 3 H 6 C H 3 C H 3 C H 3 H 0 H 3 H C H 3 E - 4 4 H C l H H H C l » H B r C H 3 z- i i l H 0 H 3 B r E - 4 6 H C l C H 3 Z - 4 6 H C H 3 C l C l H C l z-fLZ C l C l H E - 4 8 H OCH 3 H Z - 4 8 H H OCH - 36 -T a b l e 7 ( c o n t i n u e d ) N i t r i l e A B C R e f e r e n c e E - 4 9 H 0 C 2 H 5 H T h i s w o r k Z - 4 £ H H 0 C 2 H 5 E - 1 0 CH3 0 C 2 H 5 H Z-30 CH^ H O C 2 H 5 C H 3 0 C H ( C H 3 ) 2 H Z-51 C H 3 H 0 C H ( C H 3 ) 2 E-$2 C H 3 0 C ( C H 3 ) 3 H C H 3 H O C ( C H 3 ) 3 E - i l H S C 2 H 5 H H H S G 2 H 5 E - i i C H 3 S C 2 H 5 H Z - ^ C K 3 H S C 2 H 5 - 3 7 -T a b l e 8 V . p . c . d a t a f o r U n s a t u r a t e d N i t r i l e s if N i t r i l e C o l u m n Temp. F l o w r a t e R e t e n t i o n °C ( m l / m i n ) T i m e ( m i n ) 5.2 A a 142 120 Z - 3 2 10.4 E-23_ 8.8 " 155 120 Z-12 11.8 E-24 4.2 1 7 2 100 Z-^ 4 6.0 E-2i 12.2 1 2 5 100 Z-15. 6.4 E-44 . 4.0 B D 1 2 5 6 5 1-44 6.0 E-4i c 3.5 C 1 5 5 140 Z-4i 8.5 E-46 3.0 145 140 Z-46 7.8 E-48 4.0 155 100 Z-48 5.4 E-4£ 7.0 160 110 Z-4£ 9.0 E-J2O 4.4 A 173 120 Z-£0 6.4 - 38 -Table 8 (continued) N i t r i l e Column* Temp. °C Flow rate (ml/min) Retention Time(min) a 185 6.0 A 110 8.0 E-£2 6.0 II 178 1 3 0 8.0 E-13. d 140 9.8 D 192 11 . 3 E-j>4 a 6 0 7 . 6 A 188 i 9.8 a 1 0*x 1/4", 1 5 # QF-1+5^ Carbowax (4000 MS), b 10«x 1/4", 20% DC - 5 5 0 . c 1 0*x 1/4", 12% DC-550+8% Carbowax (4000 MS). d 1 0'x 1/4", 20% FFAP * A l l columns on 60/80 Chrom. W. Table 9 Chemical S h i f t s and Coupling Constants f o r the N i t r i l e s of Table 7 B A \ / / \ C CN N i t r i l e A B C Chemical S h i f t ( § ) a A B C Coupling Constant (Hz) CH^ C l H 2. Old 6.90q JA,C = 1.5 Z-JI2 CH 3 H C l 2.02d 6.63q JA,B = 2.0 CH^ Br H 2. Old 7.12q JA,C = 1 .5 z-22 CH^ H Br 2 .03d 6.78q JA,B = 1 .5 E-^4 CH^ OCH3 H 1 .70d 3.81s 6.80q JA,C = 1 .5 Z-^4 C H 3 H OCH3 1 .77d 6.63q 3.83s JA,B = 1 .5 -CH 3 CH 3 H 1 .87s 1.82m 6.57m CH^ H CH 3 1 .89s 6.14m 1.96m T a b l e 9 ( c o n t i n u e d ) N i t r i l e A B C C h e m i c a l S h i f l A B : ( S ) a C C o u p l i n g I C o n s t a n t1 3 frz) E - 4 4 H C l H 5 . 9^d 7 . 2 7 d J A,C = 14 . 0 Z - 4 4 H H C l 5 . 9 3 d 7 . 0 7 d J A,B = 8 . 0 H B r C H 3 5 . 8 0 q 2 . 6 5 d J A,C = 1 .5 H C H 3 B r 5 . 9 8 q 2 . 5 4 d J A,B = 1 .2 E-46 H C l C H , 3 5 . 5 3 q 2 . 4 3 d J A,C = 1 . 3 Z-46 H CH, C l 5 . 6 0 q 2 . 3 3 d J A,B = 1 . 3 E-42 C l H C l 7 .07s C l C l H 7 . 3 2 s E-48 H OCH^ H 4 . 6 6 d 3 . 7 5 s 7.24d J A,C = 1 3 . 0 Z-48 H H OCH, 4 . 3 3 d 6 . 8 8 d 3 . 9 2 s J A,B = 6 . 5 E - 4 £ Z - 4 £ H H OCH 2CH 3 H H O C H 2 C H 3 4 . 6 3 d 4 . 3 1 d 3 . 9 4 q 1 . 3 5 t 6.81d 7 . 2 2 d 4 . l 4 q 1 . 3 8 t J A,C J A,B = 1 3 . 0 = 7 . 0 J C H 2 , C H 3 = 7 . 3 J C H 2 , C H 3 = 7 , 3 Table 9 (continued) N i t r i l e A B G Chemical Shift (§) a A B C Coupling I Constant*3 [Hz) z.-iP. CH^ CH^ OCHgCH^ H H OCH2CH3 1 . 7 3 d 1 . 7 5 d 4 . 0 5 q 1 . 3 3 t 6.68q 6 . 8 5 q 4.01q 1 . 3 3 t JA,C JA,B 1 . 5 1 . 5 JCH 2,CH 3 = *^ CH2$ CH3 7 . 5 7 . 5 CH^ CH^ OCH(CH3)2 H H 0CH(CH3)2 1 . 7 3 d 1 . 7 5 d 4.18m 1 . 3 1 d 6.68q 6.88q 4.13m 1 . 3 0 d JA,C JA,B 1 . 5 1 . 5 JCH,(CH 3) 2  JCH,(CH 3) 2 = 7.0 = 7.0 E-j>2 CH3 OC(CH 3) 3 H 1 . 7 2 d 1.37s 7 . 0 3 q JA,C = 1 . 5 z-ii CH^ H OC(CH 3) 3 1 . 7 5 d 6.82q 1 . 3 5 s JA,B S B 1 . 5 E - i l z-il H H SCH2CH3 H H SCH^CHL 2 3 5.22d 5.29d 2.85q 1.37t 7 . 2 3 d 7 . 4 0 d 2 . 9 3 q 1 . 3 7 t JA,C JA,B 16.0 11.0 JCH 2,CH 3 = ^CH2>CH3 7.0 7.0 E - ^ 4 z-ii CH, CH, SCH2CH3 H H SCH2CH3 1.85d 1.98d 2.82q 1 . 3 5 t 6.78q 7.00q 2.82q 1 . 3 5 t JA,C JA,B 1 . 5 1 . 5 *^CH21CH3 *^ CH2> CH3 7.0 7.0 a s, singlet* d, doublet; t, t r i p l e t ; q, quartet; m, multiplet. A l l spectra were recorded as 10-20$ solutions in CClj. with TMS as internal standard, b J = +0.1 Hz. - 42 -w i t h a / ^ - p r o t o n o r a l k y l g r o u p a p p e a r i n g a t a l o w e r f i e l d i n t h e n.m.r. s p e c t r a . The c o n f i g u r a t i o n Z_ was a s s i g n e d t o t h e i s o m e r w i t h a / j ' - p r o t o n o r a l k y l g r o u p a p p e a r i n g a t a h i g h e r f i e l d i n t h e n.m.r. s p e c t r a . 3 - C h l o r o m e t h a c r y l o n i t r i l e , E - and Z- (32) The i s o m e r i c 3 - c h l o r o m e t h a c r y l o n i t r i l e s w e r e p r e -p a r e d f r o m c h l o r o a c e t o n e c y a n o h y d r i n (62) a c c o r d i n g t o t h e p r o c e d u r e o f H u r d a nd R e c t o r ( 6 5 ) . The i s o m e r s w e r e s e p a r -a t e d b y v . p . c . A s m a l l amount o f 2 - c y a n o - l , 2 - d i c h l o r o -p r o p a n e (6^) was a l s o f o r m e d . H CN C l CN OH P y r i d i n e \ / \ / C1CH - C - CH > / = < > = < C N 3 S 0 C 1 2 Ci X C H 3 H C H 3 62 E-22 Z-22 3 - B r o m o m e t h a c r y l o n i t r i l e , E - a n d Z- (33) The r e a c t i o n s e q u e n c e o f G a r d n e r a n d M c G r e e r (4-5) was u s e d t o p r e p a r e t h e a b o v e c o m p o u n d s . D e h y d r o b r o m i n a -H CN \ / B r o / C C l i , Jr==\ C H 2 B r - C B r ( C N ) C H 3 H CH, , 1 3 64 H CN KOH/t-BuOH B r CN B r \ H 3 H 7 \ J H E -22 z-22 - 43 -t i o n o f t h e b r o m i n e a d d i t i o n p r o d u c t (64) o f m e t h a c r y l o -n i t r i l e w i t h p o t a s s i u m h y d r o x i d e i n t - b u t a n o l p r o v i d e d t h e r e q u i r e d i s o m e r s w h i c h w e r e e a s y t o s e p a r a t e b y v . p . c . 3 - M e t h o x y m e t h a c r y l o n i t r i l e , E- a n d Z- (34) T h e p r o c e d u r e o f r e f e r e n c e 45 w a s u s e d t o a c q u i r e t h e E a n d Z f o r m s o f t h e t i t l e c o m p o u n d . T h e s e p a r a t i o n o f t h e i s o m e r s w a s e f f e c t e d b y v . p . c . ^ B r ^ ^ C N C H 3 O N a ^ * \ ^ N C H 3 ° N ^ / \ / \ C H , O H / \ / \ B r C H 3 H C H 3 3 CH-jO C H 3 H C H 3 E-22 Z-22 E-J4 z-2i 3 - M e t h y l m e t h a c r y l o n i t r i l e , E- a n d Z- (35) 8 N a C N 0 H C H , - C - C H , > C H , > C H , , - C - C H - C H , 3 2 3 40* K2S0^ 3 C N ' 2 3 P y / S 0 C l 2 CHo CN A / J ^ / \ CH 3 CH 3 H CH 3 E-H Z - l i T h e e q u a t i o n s g i v e n a b o v e i l l u s t r a t e t h e s y n t h e t i c s c h e m e . T h e c y a n o h y d r i n o f m e t h y l e t h y l k e t o n e (6j£) w a s c o n -v e r t e d t o t h e E a n d Z i s o m e r s o f 3 - m e t h y l m e t h a c r y l o n i t r i l e b y u s i n g p y r i d i n e a n d t h i o n y l c h l o r i d e . T h e i s o m e r s w e r e s e p a r a t e d b y v . p . c . f o r i d e n t i f i c a t i o n a n d e q u i l i b r a t i o n . v. 3 - C h l o r o a c r y l o n i t r i l e , E - and Z- (44) A r e a c t i o n scheme s i m i l a r t o t h a t o f K u r t z e t a l (66) was e m p l o y e d t o p r e p a r e t h e a b o v e i s o m e r s . The s e p -a r a t e d i s o m e r s h a d c h e m i c a l s h i f t s a n d c o u p l i n g c o n s t a n t s c o r r e s p o n d i n g t o t h o s e g i v e n i n r e f e r e n c e 66 • E a n d Z_ w e r e f o u n d t o be i n a r a t i o o f 6 0 : 4 0 . H C0NHo „ n H CN C l CN \ / 2 p 2 ° ? > \ / v=y / — \ / \ / \ C l H C l H H H 3 - c h l o r o a c r y l a m i d e E - 4 4 Z - 4 4 3 - B r o m o c r o t o n o n i t r i l e , E - a n d Z- (4j?) The r e a c t i o n scheme o f V e s s i e r e (6?) u s e d t o p r e p a r e t h e i s o m e r i c 3 - b r o m o c r o t o n o n i t r i l e s i s o u t l i n e d b e l o w . H B r H B r \ / CuCN,HBr \ / / \ NafiN / \ H CH-Br 1 N a L , I N H , 0 CH PCN <2 68 c 2 , 3 - d i b r o m o p r o p e n e NaOH CH- CN B r CN \ / \ / H B r / \ f~ \ C H ? - C = C - CN H C H 3 H e t h e r J E-4j> Z-45. 62 - 45 -A d d i t i o n of HBr to 2 - b u t y n e n i t r i l e (6_2) gave E and Z isomers which were separated by v.p.c. and found t o be i n a r a t i o of 20:80. 3 - C h l o r o c r o t o n o n i t r i l e , E- and Z- (46) Treatment of 2 - b u t y n e n i t r i l e (6£) w i t h h y d r o c h l o r i c a c i d a c c o r d i n g t o Ve s s i e r e ' s (68) method gave the E and~-Z -iso-mers i n a r a t i o of 10:90. These were separated by v.p.c. CH, CN C l CN HCl A / \ / CH, - C = C - CN > / = = \ / = = \ C l H CH, H 62 E-46 Z-46 2 , 3 - D i c h l o r o a c r y l o n i t r i l e , E- and Z- (47) Commercially a v a i l a b l e 2 , 2 , 3 - t r i c h l o r o p r o p i o n i t r i l e . C l CN C l C l q u i n o l i n e \ / \ / CH„C1 - CCloCN — > V - —( > f c r e f l u x / \ / \ H C l H CN E-42 Z-4_2 was reacted w i t h q u i n o l i n e (69) at r e f l u x i n g temperature t o f u r n i s h E and Z isomers of 2 , 3 - d i c h l o r o a c r y l o n i t r i l e . A n a l y s i s of the product i n d i c a t e d only one peak i n the v.p.c. chromatogram. However, the n.m.r. spectrum showed - 46 -two i n d i v i d u a l proton peaks at 3 7« 3 2 and 7*07 i n a r a t i o of 7»3» corresponding to E and Z isomers. A n a l y t i c a l samples ( 90% pure) were prepared by repeated v.p.c. separ-ations, r e i n j e c t i o n s , and reseparations. 3-Methoxyacrylonitrile, E- and Z- (48) The t i t l e compounds were prepared from the a c e t a l (71) by i t s acid-catalyzed p y r o l y s i s ( 3 3 ) . The separation of isomers was achieved by v.p.c. „ H CN CH-0 C N H 3 P 0 4 \ / 3 \ / ( C H , 0 ) . C H - C H ? C N ? > > = ( ) = = = ( * 2 * 180-5" / \ / \ i 0 0 C H 3 0 H H H Ik E-48 Z-48 3 - E t h o x y a c r y l o n i t r i l e , E- and Z- (49) These compounds were prepared according to a method « ™ H 4 . CN C p H - 0 CN H o P O j . \ / 2 5\ / ( C , H c 0 ) , C H - C H 0 C N — — ) = = ( ) = ( 1 0 U ^ C 2 H 5 ° H H H 21 E-4£ Z-49. s i m i l a r to that used to prepare 48 • Acid-catalyzed pyro-l y s i s of the ac e t a l (£2) gave the desired n i t r i l e s which - k? -w e r e r e a d i l y s e p a r a t e d i n t o i n d i v i d u a l i s o m e r s b y v . p . c . The E J Z r a t i o o f t h e p r o d u c t was 7O130. The s t e r e o c h e m i s t r y o f t h e i s o m e r s was a s s i g n e d f r o m t h e i r c o u p l i n g c o n s t a n t s i n n.m.r. s p e c t r a . The b o i l i n g p o i n t s o f t h e i s o m e r s c o r r e s p o n d e d w i t h t h e l i t e r a t u r e v a l u e s ( 7 0 ) . 3 - E t h o x y m e t h a c r y l o n i t r i l e , E - ($0) T h i s compound was p r e p a r e d b y t r e a t i n g E - 3 3 w i t h s o d i u m e t h o x i d e i n e t h a n o l . V _ v C N JOZU W / \ E t O H / \ B r C H 3 C 2H^0 CK^ " E-30 3 - E t h o x y m e t h a c r y l o n i t r i l e , Z - (50) The Z - 5 0 was o b t a i n e d f r o m Z - 3 3 b y i t s r e a c t i o n w i t h s o d i u m e t h o x i d e i n e t h a n o l . B ^ , C N N&0Et ° 2 H 5^ / \ E t O H / \ H CH^ H C H 3 z-21 z-50 The t w o i s o m e r s o f £0 w e r e p u r i f i e d b y v . p . c . - 48 -The n.m.r. was used t o a s s i g n the ster e o c h e m i s t r y . 3 - I s o p r o p o x y m e t h a c r y l o n i t r i l e , E- and Z- ( 5 1 ) A mixture of 3 - ^ r o m o m e t h a c r y l o n i t r i l e w i t h E and Z isomers i n the r a t i o of 6 0 i 4 0 was t r e a t e d w i t h sodium i s o -propoxide i n is o p r o p a n o l t o prepare the t i t l e compounds. The product contained E - 5 1 and Z - 5 1 i n a r a t i o of 5 7 : 4 3 . H CN Br CN H CN . CN OPr-i \ / \ / 1-PrONa \_ / \ / / \ / \ 1-PrOH / \ Br CH 3 H CH^ i-PrO CH 3 CH3 H E-jQ I - i i Z-J^l The isomers were e a s i l y separated by v.p.c. and t h e i r s t e r e o c h e m i s t r y was assigned from n.m.r. chemical s h i f t s . 3 - t - B u t o x y m e t h a c r y l o n i t r i l e , E- and Z- ( 5 2 ) A r e a c t i o n s i m i l a r t o t h a t above was used t o o b t a i n the i s o m e r i c n i t r i l e s . The product (,5.2) contained E and Z isomers i n a r a t i o of 6 0:40. V / N B \ / N t-BuONa H \ / C N C N\ / \ / ~ ~ \ t-BuOH / \ / \ Br C H H CH 3 * " B u 0 ™3 ™3 H E - H Z-22 E - i i Z-$2 - 2+9 -The p o s i t i o n of the /^-proton i n the n.m.r. spectra of the v.p.c. separated isomers was used to assign the stereochemistry. 2-Bromoacrylonitrile, (22.) The bromine addition product of a c r y l o n i t r i l e was dehydrobrominated using potassium acetate i n a c e t i c a c i d . This method has been used e f f e c t i v e l y i n removing the a c i d i c a-hydrogen and the ^ -halogen (71)» H CN \ / B r 2 I \ e . — C H 2 B r - CHBrCN H H ether KOAc HOAc H CN \ _ y 21 3-Thioethoxyacrylonitrile, E- and Z- (53) A reaction s i m i l a r to that of Gregory ( 7 2 ) was used to obtain the t i t l e compounds. The E and Z isomers \_J* H ^ C N C 2 H 5 S V _ J N / \ EtSH / \ / \ H Br C 2H 5S H H H 21 E - n z-12 - 5 0 -were p r e s e n t i n a r a t i o o f 6 1 : 3 9 as d e t e r m i n e d b y v . p . c . The s t e r e o c h e m i s t r y was a s s i g n e d f r o m t h e o b s e r v e d c o u p -l i n g c o n s t a n t s i n t h e n.m.r. s p e c t r a . 3 - T h i o e t h o x y m e t h a c r y l o n i t r i l e , E - a n d Z- ( £ 4 ) T r e a t m e n t o f 3 - b r o m o m e t h a c r y l o n i t r i l e (^2.) w i t h a n e q u i v a l e n t amount o f s o d i u m t h i o x i d e and e t h a n t h i o l y i e l d e d t h e c o r r e s p o n d i n g 3 - t h i o e t h o x y compounds ( 4 5 ) . The i s o m e r s w e re r e a d i l y s e p a r a t e d b y v . p . c . H B r \ / / \ CN CH, E-22 B r CN / \ H CH. E t S N a E t S H C 2 H 5 S J CN CH. E - £ 4 C oH S^ 2 5 V H CN J / \ CH, - 51 -P r e p a r a t i o n o f O. , / ^ - U n s a t u r a t e d E s t e r s F o u r u n s a t u r a t e d e s t e r s w e r e o b t a i n e d t o s t u d y t h e i r e q u i l i b r i a . T h e s e e s t e r s a r e r e p r e s e n t e d i n T a b l e 1 0 . T h e y were e a s i l y s e p a r a t e d i n t o E a n d Z i s o m e r s b y v . p . c . The n.m.r. c h e m i c a l s h i f t s w e r e u s e d t o a s s i g n t h e s t e r e o c h e m i s t r y o f t h e i s o m e r s . D a t a f o r n.m.r. a p p e a r s i n T a b l e 1 1 . T a b l e 10 U n s a t u r a t e d E s t e r s P r e p a r e d f o r E q u i l i b r i a B A \ / / \ C COgCH^ E s t e r A B C R e f e r e n c e 1-15 CH, B r CHj T h i s w o r k Z - l i C H , C H 3 B r C H 3 B r C H ( C H 3 ) 2 Z - i 6 C H 3 C H ( C H 3 ) 2 B r E-12 CH, C ( C H 3 ) 3 H Z-i2 C H 3 H C ( C H 3 ) 3 Z - i 8 C ( C H , ) ^ H C H , Table 11 Chemical Shifts and Coupling Constants for the Esters B A \ / / \ C C02CH Ester A B C A Chemical B Shift C ( § )a C0 2CH 3 Coupling Constant15 (Hz) CH^ Br CH3 2.02q 2.63q 3.66s JA,C = 1-5 CH^ CH3 Br 1.86q 2.30q 3.64s JA,B = 1 , 2 CH3 CH, Br CH(CH 3) 2 CH(CH 3) 2 Br 2.03s 1.93s 2.83m 1.08d 3.33m 1.08d 3.73s 3.73s JCH,(CH 3) 2 = 6 ' 6  JCH,(CH 3) 2 = 6 ' 6 I-iZ CH, C(CH 3) 3 H 1.90d 1.20s 6.72q 3.65s JA,C = 1 , 5 z-iZ CH, H C(CH 3) 3 1.82d 5.^ 2q 1.07s 3.67s JA,B « 1-5 Z-i8 C(CH 3) 3 H CH3 1.12s 5.58q 1.64d 3.70s JB,C = 7*° a s, singlet; d, doublet; t, t r i p l e t ; m, multiplet; q, quartet. A l l spectra were recorded as 20% solutions i n CClj, with TMS as internal standard, b J = ±0.1 Hz. - 5 3 -M e t h y l 3 - b r o m o - 2 - m e t h y l - 2 - b u t e n o a t e , E - (^5_) T i g l i c a c i d was b r o m i n a t e d a n d d e h y d r o b r o m i n a t e d a c c o r d i n g t o B u c k l e s a n d Mock ( 7 3 ) m e t h o d t o p r e p a r e H COOH \ / / \ C H 3 C H 3 T i g l i c a c i d C H ^ ^COOCH^ B r . C C l , CH^CHBr - CCH^BrCOOH B r / \ C H 2 N 2 KOH JH CH C ^OH COOH CH. B r J "\ CH. 2H 3 - b r o m o a n g e l i c a c i d (2iD • E s t e r i f i c a t i o n w i t h d i a z o m e t h a n e p r o v i d e d t h e r e q u i r e d i s o m e r o f j£5_ w h i c h h a d b o i l i n g p o i n t a n d n.m.r. d a t a i n a c c o r d a n c e w i t h t h e l i t e r a t u r e v a l u e s ( 7 4 ) . M e t h y l 3 - b r o m o - 2 - m e t h y l - 2 - b u t e n o a t e , Z-T h i s p r e v i o u s l y u n r e p o r t e d i s o m e r was o b t a i n e d CH COOCH-j  3 A CH B r C00CH-, J 3 OOCH. CH. B r / \ CH. CH. / \ CH-E-15_ E-£5_ z - n b y t h e t h e r m a l i s o m e r i z a t i o n o f E - ^ 5 » The Z i s o m e r f o r m e d i n Q% y i e l d was s e p a r a t e d b y v . p . c . The p o s i t i o n o f - 5 4 -/ J - m e t h y l i n t h e n.m.r. s p e c t r u m was u s e d t o a s s i g n t h e s t e r e o c h e m i s t r y . M e t h y l 3 - b r o m o - 2 , 4 - d i m e t h y l - 2 - p e n t e n o a t e , E - a n d Z- (^6) The c r u d e d i b r o m i d e (21) o b t a i n e d b y t h e a d d i t i o n o f b r o m i n e t o a n E and Z m i x t u r e o f m e t h y l 2 „ 4 - d i m e t h y l - 2 » p e n t e n o a t e ( 7 5 ) was d e h y d r o b r o m i n a t e d u s i n g s o d i u m m e t h -o x i d e i n m e t h a n o l . Work-up o f t h i s m i x t u r e i n t h e u s u a l way a f f o r d e d a p r o d u c t t h a t c o n t a i n e d E a n d Z i s o m e r s o f ^6 i n a r a t i o o f 2 0 « 8 0 . The i s o m e r s e p a r a t i o n was a c h i e v e d b y v . p . c . a n d t h e i r s t e r e o c h e m i s t r y was a s s i g n e d f r o m t h e p o s i t i o n o f t h e m e t h i n e p r o t o n p e a k i n t h e n.m.r. s p e c t r a . ( C H 3 ) 2 C H COOCH3 ) ( « > (CH,)~CHBrCH - CCH,BrCOOCH, / \ ccii 3 2 3 3 W C H 3 C C 1 4 21 ( C H , ) 9 C H COOCH" 3 2 V / 3 CH^ONa CH 3OH B r COOCH \ / ) 2 C H C H 3 / — \ , B r C H 3 (C E-56 Z-56 M e t h y l 2 , 4 , 4 - t r i m e t h y l - 2 - p e n t e n o a t e , E - a n d Z ° (^£) The s e q u e n c e o f r e a c t i o n s t o o b t a i n t h e t i t l e compounds i s shown o n t h e f o l l o w i n g p a g e . The @ - h y d r o x y - 55 -(CHo^CHO + BrCHCOgCH^ Zn CH-(CH-)-C C 0 9 C H , H COoCH, 3 3 \ / 2 3 \ / 2 3 „ P h 3 P ether ( C H ^ C H - CHCH^COgCH, OH 2L H / — \ CH 3 ( C H 3 ) 3 C C C l i CH. z-i2 e s t e r (26) formed by the Reformatsky r e a c t i o n was de-hydrated u s i n g t r i p h e n y l phosphine and carbon t e t r a -c h l o r i d e . The product contained E and Z isomers of the r e q u i r e d compound i n 70:30 r a t i o as found by v.p.c. Methyl 2-t-butyl - 2-butenoate, Z- (58) This compound was prepared a c c o r d i n g t o the sequence of r e a c t i o n s on the f o l l o w i n g page. A l k a l i n e o x i d a t i o n of pinacolone gave 2-oxo - 3 » 3-dimethylbutanoic a c i d (22)• This a c i d was e s t e r i f i e d u s i n g diazomethane t o o b t a i n methyl 2-oxo - 3 » 3-dimethylbutanoate ( 7 8 ) . Treatment of t h i s e s t e r with e t h y l l i t h i u m a f f o r d e d (76) an d-hydroxy e s t e r (22)• The dehydration of 22 was accomplished by u s i n g p y r i d i n e and t h i o n y l c h l o r i d e to - 56 -KMnOij, , NaOH ( C H , ) , C - C - C 0 9 C H 2 8 0 CH CO-CH OH C 0 H c L i soci2 ( C H 3 ) 3 C - C - C 0 2 C H Z-£8 21 y i e l d t h e f i n a l p r o d u c t , Z - 5 8 . The s t e r e o c h e m i s t r y o f t h i s i s o m e r was a s s i g n e d f r o m t h e c h e m i c a l s h i f t o f t h e EQUILIBRATION OF OLEFINS E q u i l i b r a t i o n o f O l e f i n s o f T a b l e s 5 a n d 7 The e q u i l i b r i u m p o s i t i o n s o f t h e s e o l e f i n s a r e r e p r e s e n t e d i n T a b l e 1 2 . I n a l m o s t a l l o f t h e c a s e s t h e e q u i l i b r i u m was a c h i e v e d f r o m b o t h t h e i s o m e r s o f a p a r t i c u l a r o l e f i n . P h o t o - i n d u c e d b r o m i n e - c a t a l y z e d m e t h o d o f e q u i l i -b r a t i o n was e m p l o y e d t o e f f e c t e q u i l i b r a t i o n s o f n e a t a n d 10% s o l u t i o n s o f t h e i s o m e r s i n c a r b o n t e t r a c h l o r i d e / J - p r o t o n i n t h e n.m.r. s p e c t r u m . - 57 -a n d p e n t a n e . I n t h e a b s e n c e o f b r o m i n e v e r y s l o w i s o m e r -i z a t i o n o c c u r e d , t h u s i n d i c a t i n g t h a t t h e e q u i l i b r i u m r e a c h e d was t r u l y t h e r m o d y n a m i c . I t was a l s o o b s e r v e d t h a t no e x t r a n e o u s p e a k s a r o s e f r o m s o l v e n t b l a n k s . The a n a l y s e s o f t h e i s o m e r s was p e r f o r m e d b y v . p . c . a n d n.m.r. m e t h o d s . D i s c i n t e g r a t i o n was u s e d t o e s t i m a t e t h e p e r c e n t a g e o f t h e i s o m e r s i n v . p . c . c h r o m a t o g r a m . Where v . p . c . was u s e d f o r a n a l y s i s , i t was shown t h a t t h e r e s p e c t i v e E a n d Z i s o m e r s d i d n o t i s o m e r i z e u n d e r v . p . c . c o n d i t i o n s . The p e r c e n t a g e o f t h e i s o m e r s i s shown a s t h e a v e r a g e v a l u e a n d one " i n s t a n t " s t a n d a r d d e v i a t i o n . The " i n s t a n t " s t a n d a r d d e v i a t i o n was c a l c u l a t e d ( 7 7 ) b y m u l t i p l y i n g t h e r a n g e ( d i f f e r e n c e b e t w e e n t h e l a r g e s t a n d t h e • s m a l l e s t m e a s u r e m e n t s ) b y a f a c t o r d e t e r m i n e d b y t h e number o f m e a s u r e m e n t s made. A p p e n d i x 1 c o n t a i n s t h e m e t h o d f o r c a l c u l a t i n g I . S . D . a n d i t s v a l u e s f o r d i f -f e r e n t c o m p o u n d s . The n.m.r. m e t h o d was m a i n l y u s e d i n c a s e s w here i t was i m p o s s i b l e t o o b t a i n s e p a r a t e p e a k s c o r r e s p o n d i n g t o E a n d Z i s o m e r s i n t h e v . p . c . The i n t e g r a t i o n o f p a r t i c u l a r p e a k s o f t h e i s o m e r s i n t h e n.m.r. s p e c t r u m was u s e d t o c a l c u l a t e i s o m e r p e r c e n t a g e s . T a b l e 1 2 E q u i l i b r i u m P o s i t i o n s f o u n d f o r D i - a n d T r i s u b s t i t u t e d E t h y l e n e s S u b s t i t u e n t s P e r c e n t o f E I s o m e r a t 2 5°C M e t h o d o f E t h y l e n e C - 1 C - 2 C C l ^ P e n t a n e N e a t A n a l y s i s 22 C H ^ C N C l ? 5 . 7 t 0 . 2 7 5 . 3 1 0 . 7 6 0 . 7 + 0 . 3 v . p . c . 22. C H y C N B r 7 3 . 1 1 0 . 6 7 2 . 7 1 0 . 2 5 9 . 6 + 0 . 9 v . p . c . 2Jt C H y C N OCH 3 8 7 . 9 + 0 . 4 8 8 . 4 + . 0 . 2 7 7 . 8 + . 0 . 7 v . p . c . 21 CHyCX CH^ 2 3 . 2 + 0 . 7 2 2 . 7 ± 0 . 4 28.310.9 v . p . c . 2§. B r CH^ 2 4 . 6 + 0 . 2 2 5 . 2 + 0 . 6 2 6 . 7 t 0 . 2 v . p . c . 21 C l CH^ 2 4 . 0 + 0 . 5 3 0 . 4 + 0 . 3 2 6 . 5 ± 0 . 2 v . p . c . 2& B r B r , C H 3 71 . 6 + 0 . 4 7 3 « 7 ± 0 . 4 6 6 . 3 ± 0 . 5 v . p . c . 21 C l C1,CH ? 4 4 . 3 + 0 . 3 3 8 . 8 + 0 . 5 v . p . c . Table 12 (continued) Substituents Percent of E Isomer at 25°C Method of Ethylene C-1 C-2 CCl^ Pentane Neat Analysis 40 Br,CH 0 CH^ 12.4+0.3 11.7+0.3 14.0+0.2 v.p.c. 41 C1,CH3 CH 3 11.3+0.2 13.7t0.2 v.p.c. 42 C l Br 36.9±0.3 33.7±0.2 28.3+0.3 v.p.c. 43. Br,Cl CH 3 55.6 50.65 55.^ n.m.r. 44 CN C l 4l.5to.5 41.6+0.5 30.7±0.2 v.p.c. 4J CN Br,CH 3 58.1+0.5 57.5+.0.4 38.7*0.6 v.p.c. 46 CN Cl.CH 51.7±0.4 51.2+1.0 37.2+1.0 v.p.c. 42 CN,C1 C l 21.0 21.6 n.m.r. 48 CN 0CH, 77.Ml.3 68.6+1.5 v.p.c. Table 12 (continued) Substituents Percent of E Isomer at 25 °C Ethylene C-1 C-2 CC1, Pentane Neat Method of Analysis i i i l 52 CN CN,CH. CN,CH. CN,CH< CN CN,CH. OC2H5 0C 2H 5 OPr-i OBu-t SC 2H 5 SC 2H 5 71.1+.0.5 88.7+O.3 89.2+O.3 94.0 67.2+0.2 88.9+0.2 88.8+0.8 88.5±0.3 91.6+0.3 84.9±0.4 59.511.0 80.1+0.4 80.1+0.1 84.1+0.5 58.7±0.2 65.6+0.4 v.p.c v.p.c v.p.c v.p.c v.p.c v.p.c ON o - 6 1 -E q u i l i b r a t i o n of Unsaturated E s t e r s The e q u i l i b r i u m data f o r the unsaturated e s t e r s of Table 1 0 i s presented i n Table 1 3 • The e q u i l i b r i u m was approached from both s i d e s of the compounds except i n the case of $8 where o n l y the Z_ isomer was a v a i l -a b l e . The methods of e q u i l i b r a t i o n shown i n Table 1 3 are d e s c r i b e d i n the experimental s e c t i o n . I n a l l cases the a n a l y s i s was done by v.p.c. method. A l l attempts to e q u i l i b r a t e Z - 5 8 t o an e q u i l i b r i u m c o n c e n t r a t i o n of E - 5 8 and Z - J 5 8 were u n s u c c e s s f u l , so the e q u i l i b r i u m was b e l i e v e d t o be completely i n favor of the Z isomer. Dipole Moments The d i p o l e moments of i n d i v i d u a l isomers of o l e f i n s i n Table 1 2 are given i n Table 14. The values f o r most of the isomers have been taken from l i t e r a t u r e . The values f o r the E and Z isomers of 21 * 22 * 34 > 44 , and £ 0 were determined i n cyclohexane at 2 5 "G. The values f o r isomers t h a t were not a v a i l a b l e i n l i t -e r a t ure were c a l c u l a t e d from group moments, and are i n c l u d e d i n the Table. Appendix 2 l i s t s the values of group moments and i l l u s t r a t e s an example of c a l c u l a t i n g the d i p o l e moments from them. Table 13 Equilibrium Positions for CT ^ -Unsaturated Methyl Esters Substituents Temp. Method of fo Major Method of Ester C-2 C - 3 °C E q u i l i b r a t i o n Isomer Analysis i i CH3 CH 3,Br 2 5 210 Br2/CC1^(3100A) Thermal 9 6 . 9 + 0 . 4 E 9 2.2+0.2 E v.p.c. v.p.c. 5 i CH3 i-Pr,Br 2 5 Br 2/CC1^(3100A) 9 2 . 6 + 0 . 6 E v.p.c. 5 1 CH3 t-Bu,H 2 5 Br 2/CC1^(3100A) 9 9 . 5 0 E v.p.c. 2 5 Br 2/CC1^(3100A) 100. 0 Z v.p.c. 51 t-Bu CH3> H 2 5 CH30Na/CH30H* 1 0 0 . 0 Z and 210 Thermal 1 0 0 . 0 Z n.m.r. The ester was treated with a trace of sodium methoxide i n methanol and the mixture analyzed p e r i o d i c a l l y by v.p.c. Table 14 Dipole Moments of O l e f i n s S u b s t i t u e n t s Dipole Moment (D)  C a l c u l a t e d f o r e q u i l i b r i u m mixture O l e f i n C-1 C - 2 Observed C a l c u l a t e d of neat sample Reference E - 2 2 2 . 3 9 2 . 6 6 This work CH^CN C l 3 . 2 0 a Z-21 ^ . 1 3 5 - 3 1 E-21 2 . 4 6 2 . 6 8 CHyCN Br 3 . 2 0 a Z-23. 4 . 0 2 5 . 2 9 E - 2 4 3 . 8 9 2 . 9 7 CH ,CN OCH, 4 . 0 8 a Z - ^ 4 4 . 7 0 5 . 0 8 Table 14 (continued) Substituents Dipole Moment (D)  Calculated f o r equilibrium mixture O l e f i n C-1 C-2 Observed Calculated of neat sample Reference E - H 4.62 CH3,CN CH 3 4.22 b Z - I i 4 . 0 5 E-J6 1.69 78 Br CH 3 1.57a Z-16 1.57 E-12 1.97 C l CH 3 l . 7 8 a Z-22 1.71 E-28 1.16 Br Br,CH 3 1 . 4 l a Z-I8 1.97 Table 14 (continued) Substituents Dipole Moment (D) Calculated f o r equilibrium mixture O l e f i n C-1 C-2 Observed Calculated of neat sample Reference E - 2 2 0.84 7 8 C l C1,CH3 1 . 7 9 a Z - 2 2 2.20 E-40 2 . 1 5 CH^Br CH 3 1.68 b Z-40 1 . 5 7 E-41 2.17 CH3,C1 CH 3 1.68 Z-41 1 . 5 9 E-42 0.00 7 8 C l Br 1 . 3 2 a Z-42 1 . 5 6 Table 14 (continued) Substituents Dipole Moment (D)  Calculated f o r equilibrium mixture O l e f i n C -1 C - 2 Observed Calculated of neat sample Reference E-4_2 I . 7 9 Br,Cl CH o 1.80 b. Z - 4 j t I . 7 9 7 E - 4 4 2 . 3 1 2 .46 This work CN C l 2 . 9 i a Z - 4 4 3 . 9 2 5 . 0 4 E - 4 £ 2 . 3 2 CN Br,CH 3 4 . 4 4 b Z-fLi 5 . 3 8 E-46 2 . 3 0 CN C1,CH3 4 . 5 0 Z-46 5 . 3 9 Table 14 (continued) Substituents Dipole Moment (D) O l e f i n C-1 C-2 Observed Calculated Calculated for equilibrium mixture of neat sample Reference E-4_7_ Z-42 CN,C1 C l 4 . 0 5 2 . 1 6 2.70 E-48 2 . 7 7 Z-48 CN OCH. 4.82 3 . 5 3 E - ^ 0 Z - £ 0 CN,CH. 0C 2H 5 4 . 1 1 5 . 0 3 4 . 3 1 { This work a Dipole moment of an equilibrium mixture f o r the neat sample calculated from the observed values of E and Z isomers. b Dipole moment of an equilibrium mixture f o r the neat sample calculated from the calculated values of E and Z isomers. - 68 -Also included i n the Table are the calculated values of the dipole moments of equilibrium mixtures (equilibrium values from Table 13) of neat samples, DISCUSSION In order to extend the work of Gardner and McGreer (45) on the free energy a d d i t i v i t y concept, i t was decided to prepare 1 , 2-disubstituted and t r i -s u bstituted o l e f i n s and determine the positions of equilibrium as neat and i n non-polar solvents so that a comparison could be made between the calculated and experimental values. Some of the o l e f i n s prepared f o r t h i s study were already known i n the l i t e r a t u r e and the values of the equilibrium have been determined and discussed. How-ever, f o r the o l e f i n s that are new or for which there i s no mention i n the l i t e r a t u r e as to the equilibrium p o s i t i o n , some comment i s necessary which includes a discussion of the factors leading to equilibrium p o s i -t i o n s observed. This part i s discussed before discuss-i n g the free energy a d d i t i v i t y . - 6 9 -Factors Affecting Equilibrium Positions It is quite evident from the introductory section of this thesis that olefin s t a b i l i t y can be ascribed to many factors. These can be labelled as: I. Steric Effect: This effect includes traditional steric interactions such as encountered between the methyl and t-butyl groups of the Z isomer of methyl t-butylethylene. II. Attractive Nonbonded Interaction: This effect involves a van der Waals or electrostatic attraction between many groups. This attraction i s found be-tween halogens, between methyl and n i t r i l e , between methyl and halogens, between halogens and n i t r i l e , and between alkoxy and methyl groups ( 2 9 , 4 7 , 4 8 ) . I I I . Polar Repulsive Interaction: This effect comprises a polar repulsive interaction between two groups, such as between halogens and esters, between methoxy and n i t r i l e , and between alkoxy and ester groups (41). In 2-halocyclohexanones, the halogen atom prefers to be in an axial position which i s a result of repuls-ive interaction of C = 0 and C—X (X=halogen) dipoles (79)• The anomeric effect which makes an equatorial - 70 -g r o u p o n t h e a n o m e r i c c a r b o n a t o m o f s u g a r s ( p y r a n o s e s ) l e s s s t a b l e , o r a n a x i a l o n e m o r e s t a b l e h a s b e e n e x p l a i n e d b y E d w a r d (80) i n t e r m s o f a p o l a r r e p u l s -i v e t e r m b e t w e e n t h e r i n g o x y g e n a n d t h e OH g r o u p . I V . C o n . j u g a t i v e S t a b i l i z a t i o n E f f e c t t T h i s e f f e c t r e p r e s e n t s a c o n j u g a t i v e s t a b i l i z a t i o n b y r e s o n a n c e o f t h e t r a n s i s o m e r c o m p a r e d t o t h e c i s i s o m e r , w h e r e t h e c a r b o n y l g r o u p i s m a r k e d l y s e n s i t i v e t o s t e r i c e f f e c t s o f c i s s u b s t i t u e n t s (42,43). V . S o l v e n t E f f e c t t T h i s l e a s t s t u d i e d p h e n o m e n o n i n c l u d e s a s t a b i l i z a t i o n o f a m o r e p o l a r i s o m e r o f a p a i r o f i s o m e r s i n a m o r e p o l a r s o l v e n t a n d v i c e v e r s a ( 3 3 ) . H a v i n g l a b e l l e d t h e s e e f f e c t s i t i s n o w p o s s i b l e t o d i s c u s s t h e p o s i t i o n s o f e q u i l i b r i u m f o r t h e n e w o l e f i n s . T h e e q u i l i b r i u m v a l u e s g i v e n i n t h e n e x t f e w p a g e s r e f e r t o t h e v a l u e s d e t e r m i n e d o n n e a t s a m p l e s o f o l e f i n s . l - B r o m o - 2 - c h l o r o e t h y l e n e (42) w a s e q u i l i b r a t e d a n d t h e E:Z e q u i l i b r i u m r a t i o w a s f o u n d t o b e 28i72. C l B r B r B r C l C l \ / \ / \ / >r^H „ ^ „ ,r~\ Z-42, 72% Z-6, 61% Z-2, 81% - 71 -T h i s v a l u e i s i n l i n e w i t h t h e e q u i l i b r i u m p o s i t i o n s f o u n d f o r 1 , 2 - d i b r o m o e t h y l e n e ( 6 ) , 1 , 2 - d i c h l o r o e t h y l e n e (2)» and o t h e r 1 , 2 - d i s u b s t i t u t e d h a l o e t h y l e n e s ( 2 7 ) . I f t h e r e l a t i v e s i z e s o f b r o m i n e a n d c h l o r i n e a toms a r e o f a n y i m p o r t a n c e , one w o u l d e x p e c t t h e Z i s o m e r p e r c e n t a g e o f 4 2 t o be n o t g r e a t e r t h a n t h e Z i s o m e r p e r c e n t a g e o f 2 a n d n o t l e s s t h a n t h e Z i s o m e r p e r c e n t a g e o f 6 . The e x p e r i m e n t a l v a l u e l i e s b e t w e e n t h e v a l u e s f o u n d f o r 6 a n d 2» T h e g r e a t e r s t a b i l i t y o f t h e Z i s o m e r i s due t o a n o n b o n d e d a t t r a c t i o n ( e f f e c t I I ) . The E a n d Z i s o m e r s o f 1 - b r o m o - l - c h l o r o p r o p e n e ( 4 3 ) h a v e b e e n r e p o r t e d i n t h e l i t e r a t u r e b u t t h e r e i s n o r e f e r e n c e t o t h e e q u i l i b r i u m p o s i t i o n . The v a l u e d e t e r m i n e d i n t h i s w o r k was f o u n d t o s l i g h t l y f a v o r t h e E i s o m e r . The e q u i l i b r i u m p o s i t i o n was d e t e r m i n e d b y H B r \ / E-4_3_, 55% t h e n.m.r. method b e c a u s e i t was d i f f i c u l t t o e f f e c t i v e l y s e p a r a t e t h e E and Z i s o m e r s b y v . p . c . P r o b a b l y , a s l i g h t l y l a r g e r s i z e o f t h e b r o m i n e a t o m c o m p a r e d t o t h e c h l o r i n e a t o m may be r e s p o n s i b l e f o r a s l i g h t l y h i g h e r s t a b i l i t y o f - 7 2 -the E isomer, because other nonbonded a t t r a c t i o n s ( e f f e c t I I ) between bromine and methyl and between c h l o r i n e and methyl are about the same. The e q u i l i b r i u m p o s i t i o n f o r 3-methylmethacrylo-n i t r i l e (J3J>.) i s 72% i n f a v o r of the Z isomer. A s t e r i c r e p u l s i v e term ( e f f e c t I ) as found i n cis - 2-butene would C H3 CN C H3 CN C H3 H \ / \ / \ / }/ \:H 3 / \ i K ^ C H 3 z-2i, 72% z-2, 56% 76% d e s t a b i l i z e E-35. The nonbonded a t t r a c t i v e term ( e f f e c t I I ) found i n Z-2. would be expected t o be s m a l l f o r Z-35, as observed i n t h i s study. The e q u i l i b r i u m p o s i t i o n s f o r the E and Z isomers o f 3-bromocrotononitrile (4£) and 3 - c h l o r o c r o t o n o n i t r i l e (46) were e s t a b l i s h e d by the bromine-catalyzed method. The values determined are 62% and 63% f o r the Z isomers o f 45. and 46, r e s p e c t i v e l y . A much s t r o n g e r nonbonded Br CN C l CN \ / \ / CH^ \{ CH^ Z - 4 £ , 62% Z-46, 63% - 73 -a t t r a c t i v e t e r m ( e f f e c t I I ) b e t w e e n h a l o g e n s a n d n i t r i l e t h a n b e t w e e n m e t h y l and n i t r i l e s t a b i l i z e s t h e Z i s o m e r s o f t h e s e compounds* T h i s e f f e c t c a n be v i s u a l i z e d b y l o o k i n g a t t h e e q u i l i b r i u m p o s i t i o n s o f c r o t o n o n i t r i l e (,3_)» 3 - b r o m o a c r y l o n i t r i l e (4) (33) a n d 3 - c h l o r o a c r y l o -n i t r i l e (44) a s f o u n d i n t h i s w o r k a s w e l l a s i n t h e l i t e r a t u r e (49). C H o CN B r CN C l CN A / \ / \ / Z-2, 56% Z-4, 68% Z-44, 69% T h o u g h t h e r e a r e a f e w r e f e r e n c e s i n t h e l i t -e r a t u r e r e g a r d i n g t h e p r e p a r a t i o n o f 1 , 2 - d i c h l o r o a c r y l o -n i t r i l e (4_7_) t h e r e i s no m e n t i o n o f t h e e q u i l i b r i u m p o s i t i o n . The e q u i l i b r i u m v a l u e f o u n d i n t h i s w o r k i s g i v e n b e l o w . T h i s v a l u e w h e r e two c h l o r i n e s a r e c i s H CN H H \ / \ / C^ L C l c / \l Z-4_2, 78% Z-2, 81% o r i e n t e d i s r o u g h l y t h e same a s f o u n d f o r 1 , 2 - d i c h l o r o -e t h y l e n e (£) w h e r e t h e Z i s o m e r , two c h l o r i n e s c i s o r i e n t e d , - 74 -i s about 81$. This indicates a stronger chlorine-chlorine nonbonded a t t r a c t i o n than a c h l o r i n e - n i t r i l e a t t r a c t i o n ( e f f e c t II) as found i n 3-chloroacrylonitrile (44). The v.p.c. separation of the isomers was very d i f f i c u l t , so the n.m.r. method was employed to determine the equilibrium p o s i t i o n by i n t e g r a t i n g the proton signals of the isomers i n the spectrum. 3-Methoxyacrylonitrile (48) and 3-ethoxyacrylo-n i t r i l e (4£) were prepared and the equilibrium positions f o r these were determined. Both of these compounds are more stable i n the E configuration than i n the Z configu-r a t i o n . This i s to be expected on the basis of the polar H CN H CN \ / V / <mj> \ C2H5°// ^ H E-48, 68% E-4£, 60% repulsive i n t e r a c t i o n ( e f f e c t I I I) as evidenced by Gardner and McGreer (4l) between methoxyl and n i t r i l e groups. They also point out that /^-methoxy group by conjugation would be i n the plane of the double bond and i n such a s i t u a t i o n would be very s e n s i t i v e to s t e r i c e f f e c t s of the c i s substituents (42,43). Under such circumstances the e f f e c t i v e bulk of the methoxy group can be greater - 75 -t h a n a t - b u t y l g r o u p a s shown b y t h e i r s t u d i e s o f t h e f o l l o w i n g c o m p o u n d s . t - B u CN t - B u CN \ / \ / / \ ,/ \ CH^O H CH^O CH^ E-16, 60% E-18, 92.5% H o w e v e r , t h i s d o e s n o t seem t o be t h e c a s e a s one c o m p a r e s t h e E i s o m e r p e r c e n t a g e o f 48 w i t h t h e E i s o m e r p e r c e n t a g e o f 2 i t f o u n d b y G a r d n e r a n d M c G r e e r (45) a n d r e d e t e r m i n e d b y t h e a u t h o r . On s t e r i c g r o u n d s H CN H CN \ / \ / CH cn^o CH-E - 4 8 , 68% E - 3 4 , 78% one w o u l d e x p e c t t h e E-34 p e r c e n t a g e t o be l e s s t h a n t h a t o f E - 4 8 a B u t b e s i d e s t h e p o l a r r e p u l s i v e t e r m ( e f f e c t I I I ) b e t w e e n m e t h o x y a n d n i t r i l e p r e s e n t i n b o t h 48 a n d _2iL» t h e r e i s a n a d d i t i o n a l n o n b o n d e d a t -t r a c t i o n ( e f f e c t I I ) b e t w e e n m e t h y l a n d m e t h o x y g r o u p s o f 24 o n l y , h e n c e m a k i n g i t more s t a b l e . I t seems t h a t t h e s t e r i c r e q u i r e m e n t o f t h e m e t h o x y g r o u p i s v e r y s m a l l i n E - 3 4 . T h e s e same e f f e c t s seem t o be o p e r a t i n g i n t h e - 7 6 -f o l l o w i n g compounds w h e r e a g a i n t h e E i s o m e r p e r c e n t a g e i s e n h a n c e d d e s p i t e t h e f a c t t h a t t h e s i z e o f t h e a l k o x y g r o u p h a s b e e n i n c r e a s e d . F u r u k a w a e t a l ( 4 0 ) i n d i c a t e d H CN H CN H CN \ / \ / \ / n „ / V / \ / \ C 2 H 5 0 C H 3 i - P r O CH^ t-BuO CH^ E-£0, 80$ 1-^1, 80$ 84$ f r o m t h e s p e c t r o s c o p i c s t u d i e s o f C a h i l l e t a l ( 8 1 ) a n d P o t t a n d N y q u i s t ( 8 2 ) t h a t , w h i l e t h e m e t h y l v i n y l e t h e r i s p r e d o m i n a n t l y o f S - c i s s t r u c t u r e ($2), t h e t - a l k y l v i n y l e t h e r i s p r e d o m i n a n t l y o f n o n - S - c i s f o r m , a n d p r i m a r y a n d s e c o n d a r y a l k y l v i n y l e t h e r s l i e i n - b e t w e e n t h e t w o c a s e s . So t h e c o n f o r m a t i o n o f t h e a l k o x y g r o u p V . / / C H 3 52 i n £ 0 , j>l_, a n d $ 2 i s s u c h a s n o t t o c a u s e a n y s t e r i c i n t e r -a c t i o n s ( e f f e c t I ) w i t h t h e c i s m e t h y l g r o u p , h e n c e more s t a b l e i n t h e E c o n f i g u r a t i o n . To s u m m a r i z e , i t c a n be s a i d t h a t t h e r e i s a n i n t e r p l a y o f t h r e e e f f e c t s , t h a t t h e c o n f o r m a t i o n o f t h e - 77 -a l k o x y g r o u p i s s u c h t h a t i t d o e s n o t h a v e a m a j o r s t e r i c i n t e r a c t i o n ( e f f e c t I ) , n o n b o n d e d a t t r a c t i o n s b e t w e e n c i s m e t h y l a n d a l k o x y g r o u p s ( e f f e c t I I ) a r e a p p r e c i a b l e , a n d t h e p o l a r r e p u l s i v e t e r m ( e f f e c t I I I ) b e t w e e n t h e a l k o x y a n d t h e n i t r i l e g r o u p s w h i c h make t h e i s o m e r s o f compounds 2ii a n <* iL§_ - $2 more s t a b l e i n t h e E c o n f i g u r a t i o n t h a n i n t h e Z c o n f i g u r a t i o n . E q u i l i b r i u m P o s i t i o n s o f Some U n s a t u r a t e d E s t e r s m e t h y l 3 - b r o m o - 2 - m e t h y l - 2 - b u t e n o a t e (££) h a s b e e n d e s c r i b e d i n t h e l i t e r a t u r e , t h e r e i s n o e v i d e n c e a v a i l a b l e a b o u t t h e e x i s t e n c e o f i t s o t h e r i s o m e r , i . e . t h e Z i s o m e r . I t s e x i s t e n c e was e s t a b l i s h e d h e r e w h i l e s t u d y i n g t h e b r o m i n e - c a t a l y z e d e q u i l i b r a -t i o n o f E - 5 5 . The Z_ i s o m e r was f o u n d t o be a p p r o x -i m a t e l y k% i n t h e v . p . c . a t e q u i l i b r i u m . The c o n f i g u -r a t i o n o f t h e Z_ i s o m e r was d e t e r m i n e d b y n.m.r. The e q u i l i b r i u m p o s i t i o n f o r i s i n l i n e w i t h t h a t o f T h o u g h t h e p r e p a r a t i o n o f t h e E i s o m e r o f CH H COOCH \ 3 / — V B r CH 3 E-15., 96% E - 1 0 , > 99% - 78 -m e t h y l 3 - b r o m o m e t h a c r y l a t e a s d e t e r m i n e d i n t h i s l a b -o r a t o r y b y Y.Y. W i g f i e l d ( 3 9 ) . I n o n e w o u l d e x p e c t t h e s m a l l e r b r o m i n e a t o m r a t h e r t h a n t h e m e t h y l g r o u p t o be c i s t o t h e c a r b o m e t h o x y g r o u p . B u t e v i d e n t l y t h e p o l a r r e p u l s i v e i n t e r a c t i o n b e t w e e n b r o m i n e a n d t h e e s t e r g r o u p s ( e f f e c t I I I ) and n o n b o n d e d a t t r a c t i o n b e t w e e n b r o m i n e a n d t h e m e t h y l g r o u p s ( e f f e c t I I ) o u t w e i g h t h e s t e r i c e f f e c t s o f b r o m i n e a n d m e t h y l a n d make t h e E i s o m e r o v e r w h e l m i n g l y i m p o r t a n t c o m p a r e d t o t h e Z i s o m e r . I t s h o u l d a l s o be n o t e d t h a t t h e c o n j u g a t i v e a b i l i t y o f b r o m i n e , w h i c h i s g r e a t e r t h a n t h a t o f t h e m e t h y l g r o u p , m u s t a l s o i n f l u e n c e t h e e q u i l i b r i u m p o s i t i o n . T h i s i s c l e a r f r o m t h e e q u i l i b r i u m p o s i t i o n s t u d i e d b y M c G r e e r a n d c o w o r k e r s ( 3 7 ) f o r t h e compound m e t h y l t i g l a t e ( 8 ) , H COOCHq 3 E - 8 , 8 6 $ H o w e v e r , one s t a r t s t o f e e l t h e s t e r i c e f f e c t o f t h e m e t h y l i n w h i c h i s a b s e n t i n 10. a s "the p e r c e n t a g e o f t h e E i s o m e r i n h a s s l i g h t l y d e c r e a s e d f r o m t h e p e r -c e n t a g e o f t h e E i s o m e r i n 1 0 , A t t h i s t i m e i t was d e c i d e d t o s u b s t i t u t e a - 79 -bulkier a l k y l group at the /^-position i n 1_0. The r e s u l t -ant compound a f t e r the introduction of an isopropyl group i s methyl 3-"bromo-2,4-dimethyl-2-pentenoate ( ^ 6 ) , the E and Z isomers of which were prepared. Despite the bulk of the isopropyl group, the E isomer i s s t i l l the predom-inant one, though i t s proportion has decreased from that o f compounds 1J3 and Again, the polar repulsive term (CHo)oCH C O O C H - Br. C O O C H o 3 2 \ / 3 \ _ / 3 ^H 3 ( C H 3 ) 2 C H / — \ K / u 3 E - £ 6 , 93% Z-56, 7% between bromine and the ester groups (effect I I I ) , nonbonded a t t r a c t i o n between bromine and methyl groups ( e f f e c t I I ) , and the better conjugative a b i l i t y of bromine over that of isopropyl group help explain the dominance of the E isomer. However, Gardner and McGreer (4l) pointed out that the halogen-ester polar repulsive term i s l a r g e l y overcome as seen from t h e i r comparison of methyl 3-chloro -2-butenoate (23) and methyl 3-chloro-4-methyl-2-pentenoate . (24). CH 3 COOCHo (CH^)pCH COOCH-\ / 3 3 d \ / 3 / \ / = \ H Cl \ C l n U l "H E-2JJ, 87.5# E-24, 8.5% - 80 -Therefore, the g r e a t e r s t a b i l i t y of the E isomer o f £6 m a y °e due t o a nonbonded a t t r a c t i o n between halogens and methyl groups ( e f f e c t I I ) present i n E -56 but absent i n E-2k, and l a r g e r s t e r i c i n t e r a c t i o n ( e f f e c t I ) between the c i s i s o p r o p y l and the methyl groups present i n Z -56 but absent i n Z-24, as seen below. Br C00CH, C l C00CH, \ / 3 \ / 3 , , / \ / \ (CH 3) 2CH CH 3 (CH 3) 2CH H 7% Z-24, 9 1 . 5 $ E f f o r t s t o reach the e q u i l i b r i u m p o s i t i o n f o r & a t h igher temperature (210°C) i n sealed tubes were not v e r y s u c c e s s f u l . Besides E and Z isomers there i s a l s o the formation of another compound which was l a t e r i d e n t i -f i e d as 2 , 4 , 4 - t r i m e t h y l a n g e l i c a l a c t o n e (60) by comparison of i t s n.m»r. and i . r . s p e c t r a w i t h t h a t r e p o r t e d f o r 6p_ by Y.Y. W i g f i e l d ( 3 9 ) . R e s u l t s f o r the p y r o l y s i s of the E isomer of $6 are given i n Table 1 5 . - 81 -F o r m a t i o n o f b u t e n o l i d e 6_0 f r o m t h e b r o m o e s t e r ( 5 6 ) b y t h e l o s s o f m e t h y l b r o m i d e i s n o t w i t h o u t p r e c e -d e n t ( 3 9 , 4 1 , 8 3 ) . The e q u i l i b r i u m r e s u l t s a t 2 1 0°G a r e c o m p l i c a t e d b y t h e f o r m a t i o n o f 6 0 . H o w e v e r , t h e f a c t t h a t t h e v a l u e o f 4 $ f o r t h e Z i s o m e r o f 3 6 i n t h e p y r o -l y s i s m i x t u r e i s c l o s e e n o u g h t o t h e v a l u e o f 7% f o u n d f o r t h e same i s o m e r b y t h e p h o t o - i n d u c e d b r o m i n e - c a t a l y z e d i s o m e r i z a t i o n m e t h o d s u g g e s t s i t t o be o f t h e r i g h t o r d e r o f m a g n i t u d e . T a b l e 15 P y r o l y s i s o f E-$6 a t 210 °C Bromo Bromo T i m e e s t e r e s t e r B u t e n o l i d e ( h ) Z-56 6 0 0 1 0 0 . 0 0 0 1 8 9 . 8 3 . 0 2 7.18 2 8 3 . 5 3 . 0 1 3 . 5 3 7 7 . 3 6 3 . 0 1 1 9 . 6 3 4 4 7 . 5 0 1.64 5 0 . 8 6 24 0 1.04 9 8 . 9 6 1 0 6 0 0 9 9 . 9 0 The E a n d Z i s o m e r s o f m e t h y l 2 , 4 , 4 - t r i m e t h y l - 2 -p e n t e n o a t e ($2) w e r e p r e p a r e d a nd t h e e q u i l i b r i u m was - 82 -d e t e r m i n e d . The E i s o m e r o f $2. w a s f o u n d t o be t h e p r e d o m i n a n t i s o m e r a s e x p e c t e d f r o m t h e s t u d i e s o f M c G r e e r a n d Wai : on m e t h y l 2 - m e t h y l - 2 - b u t e n o a t e ( 8 ) ( 3 ? ) a n d m e t h y l 2 , 4 - d i m e t h y l - 2 - p e n t e n o a t e (£) ( 3 8 ) . H COOCH, H GOOCHo H COOCH, (G H 3 ) 3 G CH 3 CH^ ^CH 3 ( C H ^ C l i E-12» >99f° E - 8 , 86% E-9_, 8k% M o l e c u l a r m o d e l s i n d i c a t e t h a t t h e s t e r i c i n t e r a c t i o n b e t w e e n t h e t - b u t y l a n d t h e m e t h y l g r o u p i s o f l e s s s e v e r e n a t u r e t h a n b e t w e e n t h e t - b u t y l a n d t h e c a r b o -m e t h o x y g r o u p s ( 8 4 ) , a f a c t o r r e s p o n s i b l e f o r t h e g r e a t e r s t a b i l i t y o f t h e E i s o m e r o f 5 7 » S w i t c h i n g t h e p o s i t i o n s o f t h e m e t h y l a n d t h e t - b u t y l g r o u p s o f j[7_ r e s u l t s i n t h e f o r m a t i o n o f m e t h y l 2 - t - b u t y l - 2 - b u t e n o a t e (j>8), t h e Z i s o m e r o f w h i c h was p r e p a r e d . The e q u i l i b r i u m was f o u n d t o be 100% i n f a v o r C H 3 COOCH., H C ( C H 3 ) 3 Z - ^ 8 , 100% o f t h e Z i s o m e r a s a l l a t t e m p t s t o o b t a i n t h e o t h e r i s o m e r - 83 -b y e q u i l i b r a t i o n o f Z gave o n l y one p e a k i n t h e v . p . c . c o r r e s p o n d i n g t o t h e s t a r t i n g m a t e r i a l . A g a i n , t r a d i -t i o n a l s t e r i c f a c t o r s , m e t h y l - c a r b o m e t h o x y v e r s u s m e t h y l -t - b u t y l , a r e r e s p o n s i b l e f o r t h e d o m i n a n c e o f t h e Z i s o m e r . I t i s i n t e r e s t i n g t o n o t e , i n c o n c l u d i n g t h i s d i s c u s s i o n , t h a t s t e r i c f a c t o r s a r e o f more i m p o r t a n c e i n d e a l i n g w i t h t h e e q u i l i b r i a o f compounds o f t h e t y p e 5 7 a n d When h a l o g e n s a r e a l s o p r e s e n t (compounds 5 5 a n d j> 6 ) , t h e p o l a r e f f e c t s s t a r t t o o p e r a t e a s w e l l . H o w e v e r , i n t h e n i t r i l e s i t was f o u n d t h a t s t e r i c e f f e c t s a r e o f l e a s t c o n s i d e r a t i o n w h e r e a s p o l a r e f f e c t s m o s t l y d o m i n a t e t h e e q u i l i b r i a . A s s i g n m e n t o f C o n f i g u r a t i o n The v . p . c . s e p a r a t e d i s o m e r s o f o l e f i n s p r e v i o u s l y p r e p a r e d i n t h e l i t e r a t u r e b u t a l s o made f o r t h i s s t u d y w e r e i d e n t i f i e d b y c o m p a r i s o n o f t h e i r l i t e r a t u r e p h y s i c a l a n d s p e c t r o s c o p i c p r o p e r t i e s , s o t h e s e p r e s e n t e d n o p r o b -l e m s a t a l l . The a s s i g n m e n t o f c o n f i g u r a t i o n o f t h e new compounds h a s b e e n p r i m a r i l y b a s e d on n.m.r. m e a s u r e m e n t s . The n.m.r. d a t a f o r t h e s e compounds i s i n c l u d e d i n T a b l e s 9 a n d 1 1 . T h e r e i s l i t t l e d o u b t t h a t ^ - p r o t o n o r a l k y l g r o u p c i s t o a n i t r i l e o r a c a r b o m e t h o x y g r o u p ( d i a m a g n e t i c - 84 -a n i s o t r o p y ) w i l l be a t l o w e r f i e l d (13,18), a f a c t w h i c h i s a l s o e v i d e n t f r o m t h e p r e v i o u s l y r e p o r t e d compounds o f T a b l e s 9 and 11. F o r e a c h p a i r o f i s o m e r s s t u d i e d t h e c h e m i c a l s h i f t o f ^ - p r o t o n o r a l k y l g r o u p was a s s u m e d t o be a t l o w e r f i e l d i n t h o s e i s o m e r s i n w h i c h t h e s e g r o u p s a r e c i s o r i e n t e d w i t h r e s p e c t t o t h e n i t r i l e o r c a r b o m e t h o x y g r o u p . L i k e t h e ^ - p r o t o n o r a l k y l g r o u p , t h e h y d r o g e n s o n t h e c a r b o n C i n compounds 48 a n d 4j> ( s e e T a b l e 9) a r e a l s o m o d e r a t e l y d e s h i e l d e d b y t h e d i a m a g n e t i c a n i s o t r o p y o f t h e c i s n i t r i l e g r o u p . T h i s may s u g g e s t a n S - c i s c o n -f i g u r a t i o n (61) w i t h r e s p e c t t o t h e d o u b l e b o n d f o r t h e s e H H \ / / \ CT CN \ * ; c h 2 R 48, R = H 61 51, R = CH, c o m p o u n d s . H o w e v e r , t h e h y d r o g e n s o n t h e c a r b o n C f o r t h e compounds 50, 51, a n d $ 2 ( s e e T a b l e 9) a p p e a r r o u g h l y a t t h e same p l a c e i n t h e n.m.r. s p e c t r a 0 T h i s may a d d f u r t h e r c r e d i b i l i t y t o t h e f a c t t h a t t - a l k o x y g r o u p s i n s u c h compounds a r e o f n o n - S - c i s c o n f i g u r a t i o n , a n d p r i m a r y a n d s e c o n d a r y l i e i n - b e t w e e n t h i s n o n - S - c i s a n d S - c i s s t r u c t u r e o f 6 1 . - 85 -The a s s i g n m e n t o f t h e l e s s s t a b l e Z c o n f i g u r a -t i o n o f 55 was b a s e d on t h e a s s u m p t i o n t h a t t h e ^ - m e t h y l B r C O O C H , \ / 3 r R v y j i ^ V i i , R = C H 3 56, R = C H ( C H 3 ) 2 g r o u p o f t h e E i s o m e r o f 55 w o u l d be more d e s h i e l d e d t h a n t h a t o f t h e Z_ i s o m e r (13)• B e c a u s e o f t h i s d e s h i e l d i n g e f f e c t t h e - m e t h y l o f t h e E i s o m e r a p p e a r s a t 8 2.63 c o m p a r e d t o t h a t o f t h e Z i s o m e r a t 32.30. The a s s i g n m e n t o f t h e E c o n f i g u r a t i o n t o t h e more s t a b l e i s o m e r o f e s t e r 56 was b a s e d on t h e p o s i t i o n o f t h e m e t h i n e h y d r o g e n a t § 3•83 i n t h a t i s o m e r c o m p a r e d t o t h e l e s s s t a b l e i s o m e r w i t h t h e m e t h i n e h y d r o g e n a t 82.83. T h i s c h e m i c a l s h i f t d i f f e r e n c e i s i n l i n e w i t h t h e v i e w t h a t t h e m e t h i n e h y d r o g e n o f t h e i s o p r o p y l g r o u p i s o r i e n t e d f o r s t e r i c r e a s o n s t o w a r d t h e c a r b o m e t h o x y g r o u p i n t h e E B r C H , CH3 \ / 3 \ / ^ b - O C H -C H R ' \ // 3 J H 0 E - 86 -c o n f i g u r a t i o n a n d t h u s e x p e r i e n c e s a maximum d e s h i e l d i n g e f f e c t (38,41,85) . The Z c o n f i g u r a t i o n o f m e t h y l 2 - t - b u t y l - 2 - b u t e -n o a t e ($Q) was b a s e d on p r e v i o u s o b s e r v a t i o n s made b y F r a s e r (14) a n d M c G r e e r e t a l (15*38). T h e i r r e s u l t s i n d i c a t e t h a t t h e ^ - p r o t o n s i g n a l s o f o l e f i n s o f s i m i l a r s t r u c t u r e a p p e a r b e t w e e n §6-7 when t h e p r o t o n i s c i s o r i e n t e d t o t h e c a r b o m e t h o x y g r o u p , a n d b e t w e e n § 5-6 f o r t h e p r o t o n t r a n s o r i e n t e d t o t h e c a r b o m e t h o x y g r o u p . S o l v e n t E f f e c t s on E q u i l i b r i a I t was r e c o g n i z e d t h a t t h o u g h t h e r e i s a w i d e v a r i e t y o f d a t a on t h e e q u i l i b r i a o f o l e f i n s i n t h e l i t -e r a t u r e , t h e v a l u e s h a v e b e e n made m a i n l y on n e a t s a m p l e s a t a v a r i e t y o f t e m p e r a t u r e s , t h u s i n t r o d u c i n g unknown s o l v e n t a n d t e m p e r a t u r e e f f e c t s . The e f f e c t s o f s o l v e n t s ( e f f e c t V ) a r e s e e n f r o m t h e o l e f i n s i n T a b l e 2 t h a t w e r e s t u d i e d b y Page (33). The f o l l o w i n g t r e n d s a p p e a r f r o m t h a t study» 1. The p r o p o r t i o n o f t h e i s o m e r w i t h h i g h e r " p o l a r i t y " i s i n c r e a s e d i n t h e more p o l a r s o l v e n t , i . e . s o l v e n t o f h i g h e r " p o l a r i t y . " 2. The e f f e c t n o t e d a b o v e i s g r e a t e s t p a r t i c u l a r l y when - 87 -a n i s o m e r p a i r h a s a l a r g e d i f f e r e n c e i n t h e " p o l a r i t y " o f i n d i v i d u a l i s o m e r s . The t e r m " p o l a r i t y " m e n t i o n e d f o r t h e s o l v e n t and t h e s o l u t e i s u s e d t o i n c l u d e t h e sum o f a l l i n t e r m o l e c u l a r i n t e r a c t i o n s o f w h i c h t h e s o l v e n t o r t h e s o l u t e i s c a p a b l e . H o w e v e r , i t e x c l u d e s i n t e r a c t i o n s w h i c h l e a d t o d e f i n i t e c - h e m i c a l c h a n g e s o f t h e s o l u t e s u c h a s p r o t o n a t i o n and c o m p l e x f o r m a t i o n . A s a c o n s e q u e n c e o f t h e a b o v e o b s e r v a t i o n s i t was d e c i d e d t o s t a n d a r d i z e t h e c o n d i t i o n s u s e d t o m e a s u r e t h e e q u i -l i b r i u m p o s i t i o n s o f o l e f i n s f o r a d d i t i v i t y p u r p o s e s . The s t a n d a r d c o n d i t i o n s c h o s e n w e r e t h e p h o t o - i n d u c e d b r o m i n e -c a t a l y z e d e q u i l i b r a t i o n s f o r c i s - t r a n s p a i r s o f o l e f i n s , n e a t a n d a s 10% s o l u t i o n s i n n o n - p o l a r s o l v e n t s a t r oom t e m p e r a t u r e ( 2 5 ° C ) . The n o n - p o l a r s o l v e n t s c h o s e n were c a r b o n t e t r a c h l o r i d e and p e n t a n e . T h e s e s o l v e n t s h a v e l o w b o i l i n g p o i n t s a s c o m p a r e d t o t h e b o i l i n g p o i n t s o f m o s t o f t h e i s o m e r s s t u d i e d . T h e r e f o r e , t h e v . p . c . p e a k s due t o t h e s o l v e n t s do n o t t a i l i n t o t h e i s o m e r p e a k s a n d t h u s t h e e v a l u a t i o n o f e q u i l i b r i u m p o s i t i o n s b y v . p . c . i s u s u a l l y s t r a i g h t f o r w a r d . I n o r d e r t o d i s c u s s t h e e q u i l i b r i u m p o s i t i o n s i n n o n - p o l a r s o l v e n t s , t h e o b s e r v e d v a l u e s o f d i p o l e moments - 8 8 -( f r o m t h e l i t e r a t u r e a n d m e a s u r e d i n t h i s w o r k ) o f i n d i -v i d u a l i s o m e r s h a v e b e e n i n c l u d e d ( T a b l e 1 4 ) . I n c a s e s w h e r e t h e s e d i p o l e moment v a l u e s were n o t a v a i l a b l e , t h e s e h a v e b e e n c a l c u l a t e d f r o m t h e g r o u p moment v a l u e s . A l s o i n c l u d e d i n T a b l e 14 a r e t h e v a l u e s o f d i p o l e moments o f e q u i l i b r i u m m i x t u r e s a s c a l c u l a t e d f r o m e q u i l i b r i u m v a l u e s f r o m T a b l e 12 o f n e a t s a m p l e s o f o l e f i n s . T h e s e v a l u e s i n d i c a t e t h a t t h e n e a t l i q u i d s i n mos t o f t h e c a s e s a r e c l e a r l y p o l a r l i q u i d s ( s o l v e n t s ) o r a t l e a s t m o d e r a t e l y p o l a r i n c h a r a c t e r . A t t h i s t i m e i t i s p o s s i b l e t o c o r r e l a t e , q u a l i t a t -i v e l y , t h e s o l v e n t e f f e c t s on t h e e q u i l i b r i u m p o s i t i o n s o f o l e f i n s w i t h t h e d i p o l e moments o f t h e i n d i v i d u a l i s o m e r s . A s e x p e c t e d , t h e l e s s p o l a r i s o m e r s o f i s o m e r p a i r s a r e s t a b i l i z e d a s one c h a n g e s t h e e n v i r o n m e n t t o n o n - p o l a r s o l -v e n t s . 3 - C h l o r o a c r y l o n i t r i l e ( 4 4 ) i l l u s t r a t e s t h i s e f f e c t . The n e a t s o l u t i o n a t t h e e q u i l i b r i u m ( c a l c u l a t e d d i p o l e moment 2.91) c o n t a i n s b o t h i s o m e r s E ( d i p o l e moment 2.31) a n d Z_ ( d i p o l e moment 3 * 9 2 ) . The n e a t p o l a r s o l u t i o n a t e q u i l i b r i u m c o n t a i n s 69$ o f t h e Z i s o m e r . I n a n o n - p o l a r s o l v e n t t h e p e r c e n t a g e o f t h e E i s o m e r w o u l d be e x p e c t e d t o i n c r e a s e . The E i s o m e r becomes a p p r o x i m a t e l y 4 2 $ i n p e n t a n e a n d c a r b o n t e t r a c h l o r i d e c o m p a r e d t o 31$ i n n e a t s o l u t i o n . T h i s c o r r e s p o n d s t o q u i t e a l a r g e c h a n g e i n - 89 -s o l v e n t s t a b i l i z a t i o n , -AAG", 0 . 2 8 3 k c a l i n f a v o r o f t h e E i s o m e r . S i m i l a r l y , t h e E i s o m e r ( d i p o l e moment 3»89) o f 3 - m e t h o x y m e t h a c r y l o n i t r i l e (^4) was a l s o e n h a n c e d a s t h e p o l a r s o l v e n t ( n e a t l i q u i d ) was c h a n g e d t o a n o n -p o l a r s o l v e n t and t h e Z i s o m e r ( d i p o l e moment 4 . 7 0 ) p e r -c e n t a g e d e c r e a s e d . A c r u d e e s t i m a t i o n a s t o t h e c h a n g e ( l a r g e o r s m a l l ) i n t h e e q u i l i b r i u m p o s i t i o n i n m o v i n g f r o m a p o l a r t o a n o n - p o l a r e n v i r o n m e n t c a n be e s t i m a t e d b y c o m p a r i n g t h e d i p o l e moments o f t h e i n d i v i d u a l i s o m e r s o f a n o l e f i n i c s y s t e m . The m a g n i t u d e o f c h a n g e i s l a r g e when t w o p o l a r g r o u p s ( B r , C l , CN, OCH^) a r e 1 , 2 - d i s u b s t i t u t e d . B e c a u s e o f s u c h a n a r r a n g e m e n t t h e r e i s a l a r g e d i f f e r e n c e i n d i -p o l e moments o f t h e i n d i v i d u a l i s o m e r s . T h i s i s e v i d e n t f r o m 3 - c h l o r o m e t h a c r y l o n i t r i l e ( 2 2) ( d i p o l e moments, E 2 .39? Z 4 . 1 3 ) w h e r e t h e 61$ E i n p o l a r medium ( n e a t l i q u i d ) c h a n g e d t o 76$ E i n p e n t a n e a n d c a r b o n t e t r a -c h l o r i d e . The l a r g e s t c h a n g e was f o u n d i n t h e c a s e o f 3 - b r o m o c r o t o n o n i t r i l e (45_) ( c a l c u l a t e d d i p o l e moments, E 2 . 3 2 ; Z 5 . 3 8 ) w h e r e t h e 39$ E i n n e a t l i q u i d ( p o l a r ) became 5 8 $ E i n n o n - p o l a r s o l v e n t s . The m a g n i t u d e o f c h a n g e i n t h e e q u i l i b r i u m p o s i t i o n - 9 0 -w i l l be s m a l l e r i n d e g r e e i f one p o l a r g r o u p i s p r e s e n t a t one c a r b o n a tom a n d a r e l a t i v e l y n e u t r a l o r n o n - p o l a r g r o u p ( e . g . m e t h y l ) i s p r e s e n t on t h e o t h e r c a r b o n a t o m o f a n e t h y l e n e . The n e t r e s u l t i s t h a t t h e r e i s v e r y l i t t l e d i f f e r e n c e i n t h e p o l a r i t y o f t h e two i s o m e r s o f s u c h a n o l e f i n . 1 - B r o m o p r o p e n e ( 3 6 . ) i s a p e r f e c t e x a m p l e o f s u c h a n e f f e c t ( d i p o l e moments, E 1 . 6 9 ; Z 1 . 5 7 ) . The 27% E i n p o l a r ( n e a t l i q u i d ) becomes a b o u t 2k% E i n C C l ^ , a s l i g h t s h i f t t o w a r d s t h e Z i s o m e r ( s m a l l e r d i p o l e moment). 1 , 2 - D i c h l o r o a c r y l o n i t r i l e (V7_) p r e s e n t s a u n i q u e c a s e i n t h a t t h e r e i s no c h a n g e i n t h e e q u i l i b r i u m p o s i -t i o n i n m o v i n g f r o m a p o l a r ( n e a t l i q u i d ) t o a n o n - p o l a r m e d i a d e s p i t e t h e l a r g e d i f f e r e n c e i n c a l c u l a t e d d i p o l e moments o f t h e i s o m e r s (E 4 . 0 5 ; Z 2 . 1 6 ) . The % E a s d e -t e r m i n e d b y n.m.r. m e t h o d i s a p p r o x i m a t e l y t h e same i n C C l ^ ( n o n - p o l a r ) a s i n n e a t ( p o l a r ) m e d i a . S u c h a n anom-a l y i s d i f f i c u l t t o e x p l a i n on t h e p u r e l y q u a l i t a t i v e b a s i s o f e x p l a n a t i o n o f s o l v e n t s t a b i l i z a t i o n i n c l u d e d h e r e . I n T a b l e 16 a r e g i v e n t h e e x p e r i m e n t a l e q u i l i b r i u m p o s i t i o n s o f o l e f i n s t o g e t h e r w i t h t h e o b s e r v e d o r c a l c u l a -t e d v a l u e s o f d i p o l e moments o f i n d i v i d u a l i s o m e r s . T a b l e 1 6 c o m p a r e s t h e c h a n g e s p r e d i c t e d i n t h e e x p e r i m e n t a l e q u i -l i b r i u m p o s i t i o n s , i n m o v i n g f r o m p o l a r ( n e a t l i q u i d ) t o - 91 -T a b l e 16 C h a n g e i n E q u i l i b r i u m P o s i t i o n ( E x p r e s s e d i n $ E a t E q u i l i b r i u m ) a s P r e d i c t e d f r o m D i p o l e Moments a n d Compared w i t h t h o s e O b s e r v e d Compound a n d E x p e r i m e n t a l E q u i l i b r i u m P o s i t i o n , 25° ( N e a t L i q u i d ) D i p o l e Moments ( D e b y e ) E Z P o s i t i o n i n P r e d i c t e d Change N o n - P o l a r S o l v e n t s O b s e r v e d Change C C l ^ P e n t a n e H CN \ / / \ C I C H, 2«39 ^.13 l a r g e i n c r e a s e i n $ E 76 76 E-22, 61$ H CN \ / / \ B r CH, 2.46 4 .02 l a r g e i n c r e a s e i n $ E 73 73 E-2I , 60$ H CN , \ / l a r g e )===( 3 . 8 9 4 .02 i n c r e a s e 88 88 C H 3 0 / X C H 3 i n * £ E-.24, 78$ H CN \ / * * m o d e r a t e 4 . 6 2 4 . 0 5 d e c r e a s e 23 22 C H 3 C H 3 E-15., 2 8 $ i n $ E - 92 -T a b l e 16 ( c o n t i n u e d ) Compound a n d E x p e r i m e n t a l E q u i l i b r i u m P o s i t i o n , 25° ( N e a t L i q u i d ) D i p o l e Moments ( D e b y e ) E Z P o s i t i o n i n P r e d i c t e d C hange N o n - P o l a r S o l v e n t s O b s e r v e d Change C C l ^ P e n t a n e H CH, / \ B r H 1.69 1.57 s m a l l d e c r e a s e i n $ E 25 25 E-26, 27$ PH3 s m a l l , v 1 .97 1.71 d e c r e a s e 24 Gi H in foE E-2Z> 27$ H B r \ / m o d e r a t e / . 1 . 1 6 1 . 9 7 i n c r e a s e 72 74 B / X C H 3 I N * E -E - 3 8 , 66$ \ z1 l a r g e / = < 0 .84 2 .20 i n c r e a s e 44 c / CH 3 i n * S E-22, 39$ - 93 -T a b l e 16 ( c o n t i n u e d ) Compound a n d E x p e r i m e n t a l E q u i l i b r i u m P o s i t i o n , 2 5 ° ( N e a t L i q u i d ) D i p o l e Moments ( D e b y e ) E Z P o s i t i o n i n N o n - P o l a r S o l v e n t s O b s e r v e d Change P r e d i c t e d — Change CC1, P e n t a n e H CH. \ / / \ B r CH, 2 . 1 5 1.57 s m a l l d e c r e a s e i n $ E 12 12 E-2+0, m,f0 H C l \ / * # s m a l l \ 2.17 1.59 d e c r e a s e 11 3H^ C H 3 i n $ E E - 4 1 , 1 4 $ \ B r , / l a r g e / y w 1.56 i n c r e a s e 37 34 C l H i n $ E E-42, 28$ H B r \ / * * t v 1.79 1.797 n o c h a n g e 5 5 5 1 CH, C l E - 4 2 » 5 5 $ - 9 4 -T a b l e 1 6 ( c o n t i n u e d ) Compound a n d E x p e r i m e n t a l E q u i l i b r i u m P o s i t i o n , 2 5 ° ( N e a t L i q u i d ) D i p o l e Moments ( D e b y e ) E Z P o s i t i o n i n N o n - P o l a r S o l v e n t s O b s e r v e d Change P r e d i c t e d ~ Change CC1, P e n t a n e H CN \ / / \ C l H E - 4 4 , 3 1 $ 2 . 3 1 3.92 l a r g e i n c r e a s e i n % E 42 42 CH. CN \ / B r ^ " \ E - 4 5 , 3 9 $ 2 . 3 2 5 . 3 8 v e r y l a r g e i n c r e a s e i n % E 5 8 5 8 CH. C l \ / / \ CN H * * v e r y l a r g e 2 . 3 0 5 « 3 9 i n c r e a s e i n % E 5 2 5 1 E-46, 3 7 $ c i 4 . 0 5 2 . 1 6 CN l a r g e d e c r e a s e i n % E 2 1 E - 4 _ 2 , 22% - 95 -T a b l e 16 ( c o n t i n u e d ) Compound a n d E x p e r i m e n t a l E q u i l i b r i u m P o s i t i o n , 25° ( N e a t L i q u i d ) D i p o l e Moments ( D e b y e ) E Z P o s i t i o n i n N o n - P o l a r S o l v e n t s O b s e r v e d Change P r e d i c t e d Change C C l ^ P e n t a n e H CN CH^O \ / / \ H 2.77 4.82 l a r g e i n c r e a s e i n $ E 77 E - 4 8 , 6 8 $ CN / l a r g e 4.11 5 . 0 3 i n c r e a s e 8 9 8 9 / v H-.J.1 m : C 2 H 5 0 X C H 3 i n % E E - 1 0 , 80$ C a l c u l a t e d d i p o l e moments f r o m g r o u p moments. - 9 6 -n o n - p o l a r s o l v e n t s ( p e n t a n e and C C l ^ ) , w i t h t h e c h a n g e s o b s e r v e d . The a g r e e m e n t b e t w e e n t h e p r e d i c t e d c h a n g e , o n t h e b a s i s o f d i p o l e moments o f i n d i v i d u a l i s o m e r s , a n d t h e o b s e r v e d c h a n g e i s f a i r l y g o od e x c e p t i n t h e u n i q u e c a s e o f 4_2 c i t e d e a r l i e r . F r e e E n e r g y A d d i t i v i t y H a v i n g e s t a b l i s h e d e q u i l i b r i u m p o s i t i o n s o f o l e f i n s u n d e r t h e s t a n d a r d c o n d i t i o n s d e s c r i b e d e a r l i e r i t i s now p o s s i b l e t o f u r t h e r t e s t G a r d n e r a n d McGreer»s (45) c o n c e p t o f f r e e e n e r g y a d d i t i v i t y i n o l e f i n p a i r s . A s m e n t i o n e d e a r l i e r , t h e y f o u n d e v i d e n c e f o r t h e a d d i t i v i t y o f v i c i n a l g r o u p p a i r s i n d e t e r m i n i n g t h e e q u i -l i b r i u m p o s i t i o n s f o r a t r i s u b s t i t u t e d o l e f i n . T h e i r c o n -c e p t o f a d d i t i v i t y c a n be e x p r e s s e d b y e q u a t i o n s o f g e n e r a l f o r m . X Y X X Y v _ y \ = \ / ( a ) ( b ) ( o ) X z \ / \ / (a') ( C ) - 9 7 -The e q u i l i b r i u m v a l u e K a f o r o l e f i n a i s r e p r e -s e n t e d b y ( a ) / (a' ) j t h e e q u i l i b r i u m v a l u e f o r o l e f i n b i s s i m i l a r l y r e p r e s e n t e d b y ( b ) / ( b ' ) . T h e s e e q u i l i b -r i u m v a l u e s K a a n d K b r e p r e s e n t t h e sum t o t a l o f a l l t h e s t e r i c , p o l a r , a n d a n y o t h e r i n t e r a c t i o n s b e t w e e n X and Y a n d b e t w e e n X a n d Z, r e s p e c t i v e l y . Now, t h e e q u i l i b r i u m p o s i t i o n K c f o r o l e f i n c c a n be e x p r e s s e d a s a p r o d u c t o f K a and K^, t h e f r e e e n e r g y t e r m s (AG°= - R T l n K ) . K a . K b = K c I t s h o u l d be m e n t i o n e d h e r e t h a t t h i s m e t h o d o f c a l c u l a t i n g K Q d o e s n o t t a k e i n t o a c c o u n t t h e g e m i n a l i n t e r a c t i o n s , i . e . b e t w e e n Y a n d Z. I t a l s o d o e s n o t a l l o w f o r t h e p o s s i b i l i t y o f a c h a n g e i n t h e e l e c t r o n d e n s i t y o f t h e d o u b l e b o n d . F o r t h i s s t u d y , o n l y t h e o l e f i n s w i t h s p h e r i c a l l y s y m m e t r i c and s t e r i c a l l y s m a l l e r g r o u p s ( B r , C l , CN, CH^) a r e c o n s i d e r e d f o r t h e a d d i t i v i t y r e l a t i o n s h i p . The e q u i -l i b r i u m p o s i t i o n s o f d i s u b s t i t u t e d o l e f i n s t o be u s e d f o r t h e p u r p o s e o f c a l c u l a t i n g t h o s e o f t r i s u b s t i t u t e d o l e f i n s a r e t a k e n f r o m T a b l e 2 ( 3 3 ) a n d T a b l e 1 2 ( t h i s w o r k ) . The e q u i l i b r i u m v a l u e o f 2 - b u t e n e i s t a k e n f r o m T a b l e 4 . The v a l u e was d e t e r m i n e d i n t h e s o l v e n t e t h y l e n e c h l o r i d e ( 5 3 ) • The e x p e r i m e n t a l v a l u e s o f e q u i l i b r i u m p o s i t i o n s f o r t h e - 98 -t r i s u b s t i t u t e d o l e f i n s a r e t a k e n f r o m T a b l e 12 ( t h i s w o r k ) a n d a r e e n c l o s e d i n p a r e n t h e s e s . F i g u r e 6 e x p l o r e s t h e f r e e e n e r g y a d d i t i v i t y r e l a t i o n s h i p i n g r e a t d e t a i l . A s s e e n f r o m F i g u r e 6 , t h e a g r e e m e n t b e t w e e n t h e c a l c u l a t e d a n d e x p e r i m e n t a l v a l u e s i s e x c e l l e n t e x c e p t f o r t h e l o n e c a s e o f 4_7_. The d i f f e r e n c e b e t w e e n t h e e x p e r i -m e n t a l (?8$ Z ) a n d c a l c u l a t e d ( 6 6 $ Z ) i s 12 . P r o b a b l y t h e e x p e r i m e n t a l e q u i l i b r i u m p o s i t i o n m e a s u r e d b y t h e n.m.r. m e t h o d i s n o t a s a c c u r a t e a s i t w o u l d h a v e b e e n h a d t h e v . p . c . m ethod b e e n u s e d t o m e a s u r e t h i s v a l u e . T h i s d i f -f e r e n c e o f 12 c o r r e s p o n d s t o a n e r r o r i n t h e c a l c u l a t e d f r e e e n e r g y d i f f e r e n c e o f ±0.35 k c a l . F o r t h e o t h e r o l e -f i n s o f F i g u r e 6 t h e c o r r e s p o n d e n c e o f i s o m e r p e r c e n t a g e f o u n d e x p e r i m e n t a l l y a n d c a l c u l a t e d f a l l s i n t h e r a n g e o f +7$ ( e x c e p t i n t h e c a s e o f 3 - c h l o r o m e t h a c r y l o n i t r i l e i n p e n t a n e ) . T h i s i s e q u i v a l e n t t o a n e r r o r o f ±0.21 k c a l b e t w e e n t h e e x p e r i m e n t a l a n d t h e c a l c u l a t e d f r e e e n e r g i e s . F i g u r e 6 a l s o shows t h e s u c c e s s f u l p r e d i c t e d s w i t c h o f t h e d o m i n a n t Z_ i s o m e r i n p o l a r medium t o E d o m i n a n t i n n o n - p o l a r m e d i a . I t s u c c e s s f u l l y shows t h e r e s u l t o f com-b i n i n g t h e f r e e e n e r g y c o m p o n e n t o f t h e v i c i n a l p a i r s o f d i s u b s t i t u t e d o l e f i n s t o p r e d i c t t h e e q u i l i b r i u m p o s i t i o n i n t r i s u b s t i t u t e d o l e f i n s . T h i s c a n be done i n two w a y s . - 99 -F i g u r e 6 E q u i l i b r i u m P o s i t i o n s f o u n d ( i n p a r e n t h e s e s ) a n d C a l c u l a t e d f o r T r i s u b s t i t u t e d O l e f i n s a t 25°C H CN \ / / \ C l CH 1. H H \ / H \ CN / C l ^ ^ C H 3 / C l \ H N e a t 74 Z 31 E C C l ^ 76 Z 41 E P e n t a n e 70 Z 42 E 3 56 E C (61 E ) 69 E° (76 E ) 63 E C (75 E ) H H H CN H CN' 2 \ / \ / \ / / \ / \ / \ B r C H 3 B r H B r CH^ N e a t 73 Z 32 E 56 E° (60 E ) C C I K 75 Z 45 E 7 1 E° (73 E ) P e n t a n e 75 Z 49 E 74 E c (73 E ) C H 3 H C H 3 C N 3 CN \ / \ / \ / / — \ / \ / \ H C H 3 H H H C H 3 C C l ^ 77 E * 61 Z 84 Z C (77 Z ) P e n t a n e 77 E * 61 Z 84 Z C (77 Z ) - 100 -F i g u r e 6 ( c o n t i n u e d ) 4 . B r CN \ / H CN \ / B r \ CN / / \ H H / \ CH^ H C H 7 N. N e a t 6 8 Z kk E 6 2 Z° ( 6 1 Z ) C C l ^ 5 5 Z 3 9 E 5 7 E° ( 5 8 E ) P e n t a n e 5 1 Z 3 9 E 6 1 E c ( 5 8 E ) 5 . C l CN \ / H CN \ / C l \ CN / / \ H H / \ C H 3 H CH^ \ H N e a t 6 9 Z 4 4 E 6 3 Z C ( 6 3 Z ) C C l ^ 5 9 Z 3 9 E 5 2 E C ( 5 2 E ) P e n t a n e 5 8 Z 3 9 E 5 3 E c ( 5 2 E ) 6 . H CN \ / \ / H \ CN / / \ C l H / \ C l C l / C l \ C l N e a t 3 1 E 81 Z 6 6 Z c ( 7 8 Z ) - 101 -F i g u r e 6 ( c o n t i n u e d ) 7. H CN H H H CN \ / \ / \ / / \ / \ / \ CH^ H C H 3 B r C H 3 B r N e a t k k E 73 Z 68 Z c (69 Z ) * * P e n t a n e 39 E 75 Z 66 Z c (67 Z ) 8 . H \ C l / H \ H / C l / c / \ 0 / \ C H 3 / C l \ C H 3 N e a t 19 E 74 z kO E° (39 E ) P e n t a n e 26 E 70 Z k5 £C (kk E ) CH^ \ B r / C H 3 \ C H ^ 9 . / H \ H / H \ C H 3 / H \ C H 3 C C l ^ 75 Z 77 * E 91 z c (88 Z ) P e n t a n e 75 Z 77 E * 91 z c (88 Z ) 1 0 . CH^ \ C H 3 A H / C H ^ C l / \ \ j H 3 / H \ C H 3 P e n t a n e 70 z 77 •«• E 89 Z C (89 Z ) - 102 -F i g u r e 6 ( c o n t i n u e d ) H B r H H H B r n \ / v__/ \ / / — \ / — \ / \ B r H B r CH^ B r CH, N e a t 39 E 73 Z 63 E c (66 E ) P e n t a n e 4 8 E 75 Z 73 E c (7^ E ) 12 . H \ r \ B r / / \ H / \ C H 3 C l / C H 3 \ C l N e a t 27 E 74 z 51 E C (55 E ) c c l 4 25 76 Z 51 E° (55 E ) P e n t a n e 25 E 70 Z 56 Z c (^9 Z ) c C a l c u l a t e d e q u i l i b r i u m p o s i t i o n s f r o m f r e e e n e r g y a d d i t i v i t y r e l a t i o n s h i p . * The v a l u e u s e d h e r e was d e t e r m i n e d i n e t h y l e n e c h l o r i d e ( 5 3 ) . ** T a k e n f r o m r e f e r e n c e 33* - 103 -One i s t o m u l t i p l y t h e e q u i l i b r i u m r a t i o s o f d i s u b s t i -t u t e d o l e f i n s t o o b t a i n t h e e q u i l i b r i u m v a l u e f o r t h e t r i s u b s t i t u t e d o l e f i n a s shown i n F i g u r e 6. Or t h i s i s d o n e m o s t c o n v e n i e n t l y b y c o n v e r t i n g t h e p e r c e n t - t e r m s o f d i s u b s t i t u t e d o l e f i n s t o f r e e e n e r g y d i f f e r e n c e s ( e q u i l i b r i u m r a t i o s a r e f r e e e n e r g y t e r m s , AG°= - R T l n K ) w i t h t h e h e l p o f T a b l e 1. T h e n b y a d d i n g o r s u b t r a c t i n g t h e s e , t h e f r e e e n e r g y d i f f e r e n c e s f o r t h e t r i s u b s t i t u t e d o l e f i n s c a n be f o u n d a n d t h e s e d i f f e r e n c e s c a n be c o n v e r t -e d i n t o e q u i l i b r i u m r a t i o s a g a i n w i t h t h e h e l p o f T a b l e 1, F o r e x a m p l e , t h e 68$ Z_ o f 3 - b r o m o a c r y l o n i t r i l e (4) means a f r e e e n e r g y d i f f e r e n c e o f -0.446 k c a l , a n d 44$ E o f c r o t o n o n i t r i l e Q ) means a f r e e e n e r g y d i f f e r e n c e o f +0.143 k c a l . The d i f f e r e n c e b e t w e e n t h e s e t w o numbers i s - 0 . 3 0 3 k c a l , t h a t i s , 62-63$ o f t h e Z_ i s o m e r o f 3 - b r o m o c r o t o n o -n i t r i l e (4£). The o b s e r v e d v a l u e f o r t h e same i s o m e r was f o u n d t o be 61$. T h i s m e t h o d i s u s e d t o c a l c u l a t e t h e e q u i l i b r i u m p o s i t i o n s o f some more o l e f i n s t h a t u t i l i z e t h e same k i n d o f i n t e r a c t i o n s a s a r e p r e s e n t i n t h e o l e -f i n s o f F i g u r e 6. T h e s e r e s u l t s a r e g i v e n i n F i g u r e 7« I t i s e v i d e n t t h a t t h e c o n c e p t o f f r e e e n e r g y a d d i t i v i t y f o r t h e c a s e s l i s t e d i n F i g u r e 6 i s v e r y u s e f u l . H o w e v e r , i t i s f e l t t h a t when b u l k i e r g r o u p s a r e i n v o l v e d o r t h e g r o u p s t h a t r e q u i r e s p e c i a l c o n f o r -- 104 -F i g u r e 7 C a l c u l a t e d E q u i l i b r i u m P o s i t i o n s f o r Some O l e f i n s % o f t h e P r e d o m i n a n t I s o m e r O l e f i n N e a t C C l ^ P e n t a n e B r CN \ / / \ C l H 5 1 E 5 ^ E 5 7 E Br, v _ y r H CN 5 8 E 5 1 E CH CN / / \ H C l / \ H CN B r C l \ / vf " ~ \ N 6 9 Z 6 3 Z 6 0 Z 5 4 z 5 2 z 5 8 z 5 5 z 5 8 z 6 5 z - 1 0 5 -H B r \ / 3 F i g u r e 7 ( c o n t i n u e d ) fo o f t h e P r e d o m i n a n t I s o m e r O l e f i n N e a t C C l ^ P e n t a n e 5 5 E 6 5 E 5 5 E C l r j B r 5 1 E 64 E 61 E H. m a t i o n f o r c o n j u g a t i v e p u r p o s e s a r e p r e s e n t , t h e r e l a t i o n -s h i p may n o t h o l d v e r y w e l l . The m o s t s u c c e s s f u l a p p l i c a t i o n o f t h e f r e e e n e r g y a d d i t i v i t y i n t h i s w o r k h a s b e e n t h e p r e d i c t i o n t h a t t h e d o m i n a n t Z i s o m e r o f 3 - b r o m o c r o t o n o n i t r i l e (45_) a n d 3 - c h l o r o -c r o t o n o n i t r i l e (46) i n p o l a r s o l v e n t s ( n e a t l i q u i d s ) w o u l d become E d o m i n a n t i n n o n - p o l a r s o l v e n t s , w h i c h was l a t e r o b s e r v e d t o be t h e c a s e . EXPERIMENTAL G e n e r a l S t a t e m e n t B o i l i n g p o i n t s w e re d e t e r m i n e d b y m i c r o c a p i l l a r y m e t h o d and m e l t i n g p o i n t s w e r e d e t e r m i n e d b y G a l l e n k a m p m e l t i n g p o i n t a p p a r a t u s . B o t h b o i l i n g p o i n t s a n d m e l t i n g p o i n t s a r e u n c o r r e c t e d . I n f r a r e d ( i . r . ) s p e c t r a w e r e o b t a i n e d on a P e r k i n -E l m e r M o d e l 4 5 7 s p e c t r o p h o t o m e t e r . A l l s p e c t r a were o b t a i n e d on n e a t l i q u i d f i l m s b e t w e e n s o d i u m c h l o r i d e p l a t e s u n -l e s s o t h e r w i s e m e n t i o n e d . N u c l e a r m a g n e t i c r e s o n a n c e ( n . m . r . ) s p e c t r a w e r e r e c o r d e d on a V a r i a n A s s o c i a t e s M o d e l T - 6 0 s p e c t r o m e t e r . The s p e c t r a w e r e t a k e n a s 10-20$ s o l u t i o n s i n c a r b o n t e t r a -c h l o r i d e u n l e s s o t h e r w i s e i n d i c a t e d . T e t r a m e t h y l s i l a n e was u s e d as a n i n t e r n a l s t a n d a r d . S p e c t r a n o t g i v e n i n t h e e x p e r i m e n t a l s e c t i o n c a n be f o u n d i n T a b l e s 9 and 11 . The s p e c t r a w e r e r e c o r d e d b y M i s s P. W a t s o n . V a p o r p h a s e c h r o m a t o g r a p h y ( v . p . c . ) was c a r r i e d o u t - 107 -on a n A e r o g r a p h M o d e l A - 9 0-P e q u i p p e d w i t h a t h e r m a l c o n -d u c t i v i t y d e t e c t o r . C h r o m a t o g r a m s w e r e r e c o r d e d o n a H o n e y w e l l M o d e l E l e c t r o n i k 15 r e c o r d e r e q u i p p e d w i t h a d i s c c h a r t i n t e g r a t o r . The v . p . c . p e a k a r e a s were m e a s u r -e d b y i n t e g r a t i o n . H e l i u m , w i t h i n l e t p r e s s u r e o f 50 p . s . i . , was u s e d a s t h e c a r r i e r g a s . The v . p . c . d a t a n o t r e p o r t e d i n t h e e x p e r i m e n t a l s e c t i o n c a n be l o c a t e d i n T a b l e s 6 and 8 . The o l e f i n s w e r e i r r a d i a t e d b y s u n l i g h t o r i n a R a y o n e t P h o t o c h e m i c a l R e a c t o r (The S o u t h e r n New E n g l a n d U l t r a v i o l e t Co., M i d d l e t o w n , C o n n . ) . The a p p a r a t u s was e q u i p p e d w i t h 16 ( i n t e r c h a n g e a b l e ) l a m p s w h i c h e m i t t e d r a d i a t i o n o f 3100 A. E q u i l i b r a t i o n s o f o l e f i n s w e r e c a r r i e d o u t b y t h e p h o t o - i n d u c e d b r o m i n e - c a t a l y z e d r e a c t i o n . To a s a m p l e i n a P y r e x t u b e (6-7 cm l o n g , 4 mm o . d . ) , e i t h e r n e a t o r a s 10$ s o l u t i o n s i n c a r b o n t e t r a c h l o r i d e o r p e n t a n e , was a d d e d 1-2 m o l e $ b r o m i n e a s a 10$ s o l u t i o n i n c a r b o n t e t r a -c h l o r i d e ( v / v ) . I n n e a r l y a l l t h e c a s e s 0.5 f i l b r o m i n e s o l u t i o n was a d d e d t o 100^U1 o f t h e o l e f i n s o l u t i o n . The s a m p l e t u b e n e c k s were c o n s t r i c t e d b e f o r e t h e i n t r o d u c t i o n o f t h e s a m p l e t o f a c i l i t a t e s e a l i n g . The s e a l e d s a m p l e t u b e s w e r e i r r a d i a t e d a n d r e m o v e d p e r i o d i c a l l y t o s t u d y t h e e q u i l i b r a t i o n s . - 108 -F o r t h e t h e r m a l e q u i l i b r a t i o n o f o l e f i n s , s m a l l s a m p l e s (10-50JJL1) w e r e p l a c e d i n P y r e x t u b e s ( 4 mm o.d.) a n d p l a c e d i n a f u r n a c e m a i n t a i n e d a t 2 1 0 ° . A l t h o u g h some d a r k e n i n g o f t h e s a m p l e s o c c u r r e d , t h e r e was no a p p a r e n t d e c o m p o s i t i o n . S a m p l e s were r e m o v e d , o p e n e d and a n a l y z e d a t f i x e d i n t e r v a l s . The d i p o l e moments o f t h e v . p . c . s e p a r a t e d p u r e i s o m e r s w e r e m e a s u r e d b y t h e G u g g e n h e i m m e t h o d ( 8 6 ) . A g r a d e d s e r i e s o f f i v e s o l u t i o n s o f e a c h i s o m e r was p r e p a r e d i n c y c l o h e x a n e ( s p e c t r o g r a d e , d r i e d o v e r m o l e c u l a r s i e v e s , B.D.H.. 1 3 X ) a s t h e s o l v e n t . The c o n c e n t r a t i o n o f e a c h o f t h e s o l u t i o n s was d e t e r m i n e d a s m o l e s p e r m l . A WTW D i p o l e m e t e r , Type DM0 1 , w i t h a DFL-1 c e l l was u s e d t o m e a s u r e t h e c a p a c i t a n c e o f e a c h s o l u t i o n . The c a p a c i t a n c e s o f a i r a n d c a r b o n t e t r a c h l o r i d e w e r e a l s o mea-s u r e d a s s t a n d a r d s . B e c a u s e t h e c a p a c i t a n c e o f t h e c e l l p l u s t h e c o n t e n t s i s d i r e c t l y p r o p o r t i o n a l t o t h e d i e l e c t r i c c o n s t a n t o f t h e c o n t e n t s , one c a n t h e n u s e t h e known v a l u e s o f t h e d i e l e c t r i c c o n s t a n t s o f a i r and c a r b o n t e t r a c h l o r i d e t o g e t h e r w i t h t h e i r m e a s u r e d c a p a c i t a n c e s t o d e t e r m i n e t h e c o n v e r s i o n f a c t o r s f r o m c a p a c i t a n c e t o d i e l e c t r i c c o n s t a n t f o r t h e d i p o l e m e t e r . Thus t h e d i e l e c t r i c c o n s t a n t s o f t h e s o l u t i o n s w e r e o b t a i n e d . - 109 -The r e f r a c t i v e i n d i c e s o f t h e s o l u t i o n s f o r d i -p o l e moment p u r p o s e s w e r e m e a s u r e d b y a d i p p i n g r e f r a c t o -m e t e r ( C a r l Z e i s s ) , t h e s c a l e r e a d i n g s o f w h i c h w e re c o n -v e r t e d i n t o r e f r a c t i v e i n d i c e s b y u s i n g t h e t a b l e s s u p p l i e d b y t h e m a n u f a c t u r e r . The t e m p e r a t u r e o f t h e s o l u t i o n s , when m e a s u r i n g t h e i r c a p a c i t a n c e s a nd r e f r a c t i v e i n d i c e s , was k e p t c o n s t a n t b y a r e c i r c u l a t i n g b a t h . The e l e m e n t a l m i c r o a n a l y s e s w e r e p e r f o r m e d b y M r . P . B o r d a . - 110 -C h l o r o a c e t o n e c y a n o h y d r i n , (62) C h l o r o a c e t o n e c y a n o h y d r i n was p r e p a r e d a c c o r d i n g t o t h e p r o c e d u r e o f F e r r i s a n d M a r k s ( 8 7 ) . To a s o l u t i o n o f 62.4 g (0.6 m o l e ) o f s o d i u m b i s u l f i t e i n 160 m l o f w a t e r was a d d e d , d r o p w i s e w i t h s t i r r i n g , 46.2 g (0.5 m o l e ) o f c h l o r o a c e t o n e . The t e m p e r a t u r e o f t h e s o l u t i o n was k e p t b e l o w 35°by i n t e r m i t t e n t c o o l i n g . A f t e r t h e c o m p l e t i o n o f t h e a d d i t i o n , t h e s o l u t i o n was c o o l e d t o 25°and 250 m l o f e t h e r was a d d e d . T h e n a s o l u t i o n o f 39.0 g (0.6 m o l e ) o f p o t a s s i u m c y a n i d e i n 80 m l o f w a t e r was a d d e d d r o p w i s e a t 2 5 - 3 0°with v i g o r o u s s t i r r i n g . When a l l t h e c y a n i d e s o l u t i o n h a d b e e n a d d e d , t h e e t h e r l a y e r was s e p a r a t e d a n d t h e a q u e -o u s l a y e r was e x t r a c t e d w i t h e t h e r (3 x 100 m l ) . The com-b i n e d e t h e r s o l u t i o n was d r i e d (MgSO^), e t h e r r e m o v e d u n d e r v a c u u m , a n d d i s t i l l e d u n d e r r e d u c e d p r e s s u r e t o y i e l d 4 3 . 8 g (73$) o f t h e c y a n o h y d r i n 621 b . p . 108-110720 mm [ l i t . (87) 73-7^/1-5 mm]. 3 - C h l o r o m e t h a c r y l o n i t r i l e , E - and Z- (32) The t i t l e compounds were p r e p a r e d f r o m c h l o r o a c e t o n e c y a n o h y d r i n (62.) b y t h e m e t h o d o f H u r d a nd R e c t o r ( 6 5 ) . I n t o a 1 l i t e r t h r e e - n e c k e d r o u n d b o t t o m f l a s k , e q u i p p e d w i t h a m e c h a n i c a l s t i r r e r , r e f l u x c o n d e n s e r , a n d a d r o p p i n g - I l l -f u n n e l , was p l a c e d 1 2 0 . 0 g ( 1 . 0 m o l e ) o f 6 2 . The f l a s k was t h o r o u g h l y c o o l e d i n a n i c e - b a t h , a n d t h e n 162 m l ( 2 . 0 m o l e ) o f i c e - c o l d a n h y d r o u s p y r i d i n e was s l o w l y a d d e d t o t h e f l a s k . T h r o u g h t h e d r o p p i n g f u n n e l was s l o w l y c h a r g e d 146 m l ( 2 . 0 m o l e ) o f t h i o n y l c h l o r i d e . A f t e r t h e a d d i t i o n , t h e m i x t u r e was s t i r r e d f o r 12 h a t 0°, h e a t e d f o r 3 h a t 8 0 - 9 0 ° , a n d 100 m l o f w a t e r was a d d -e d t o t h e c o o l e d r e a c t i o n m i x t u r e . S u l f u r d i o x i d e was g i v e n o f f . M o r e w a t e r a n d 10 m l o f 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 w e r e a d d e d . The d a r k s o l u t i o n was e x t r a c t e d w i t h e t h e r (6 x 200 m l ) , d r i e d ( N a 2 S 0 ^ ) f o r 12 h , c o n c e n -t r a t e d , a n d d i s t i l l e d (140-175°) t o y i e l d 80 g o f t h e f i n a l p r o d u c t . T h i s was f o u n d t o c o n t a i n 4 1 $ E - 3 2 , 5 0 $ Z-32, a n d 9 $ o f 2 - c y a n o - l , 2 - d i c h l o r o p r o p a n e (6_2) a s d e t e r m i n e d b y v . p . c . The E and Z_ i s o m e r s w e r e s e p a r a t e d b y v . p . c . a n d i d e n t i f i e d . E-22» i . r . 2 2 2 5 (C'=N) and 1 6 0 8 cm" 1 ( C = C ) . Z - 2 2 : i . r . 2222 (CSN) a n d 1 6 1 0 cm" 1 ( C = C ) . The n.m.r. s p e c t r a f o r t h e s e i s o m e r s a r e c o n s i s t e n t w i t h t h o s e r e p o r t -e d i n t h e l i t e r a t u r e ( 4 5 ) . F o r 6j_t n.m.r. § 2 . 0 3 ( s i n g l e t , 3 p r o t o n s ) , 3*7 and 3 * 9 2 (2 d o u b l e t s , 1 p r o t o n e a c h , J = 12.0 H z ) . 3 - B r o m o m e t h a c r y l o n i t r i l e , E - a n d Z- ( 3 3 ) The t i t l e compounds w e r e o b t a i n e d a c c o r d i n g t o t h e - 112 -m e t h o d o f G a r d n e r a n d M c G r e e r ( 4 5 ) . To t h e w e l l s t i r r e d 3 3 * 5 g ( ° » 5 m o l e ) o f m e t h a c r y l o n i t r i l e was a d d e d 80 g ( 0 . 5 m o l e ) o f b r o m i n e i n 5 0 m i o f c a r b o n t e t r a c h l o r i d e . The a d d i t i o n was c o m p l e t e d o v e r a p e r i o d o f 3 h, a f t e r w h i c h t h e s o l u t i o n was l e f t s t i r r i n g o v e r n i g h t a t r o o m t e m p e r a t u r e . R e m o v a l o f t h e s o l v e n t b y r o t a r y e v a p o r a t i o n y i e l d e d 5 6 g (49$) o f c r u d e 2 - c y a n o - l , 2 - d i b r o m o p r o p a n e (64). The c r u d e 64 was d i s s o l v e d i n 5 0 m l o f t - b u t a n o l , a n d t o t h i s was a d d e d 18 g o f p o t a s s i u m h y d r o x i d e i n 3 2 m l o f w a t e r . The s o l u t i o n was s t i r r e d f o r 24 h, t h e p o t a s s i u m b r o m i d e p r e c i p i t a t e was r e m o v e d b y f i l t r a t i o n . The f i l t r a t e w as d i l u t e d w i t h 1 0 0 m l o f e t h e r a n d t h e e t h e r l a y e r was s e p a r a t e d . The a q u e o u s l a y e r was f u r t h e r e x t r a c t e d w i t h e t h e r ( 2 x 1 0 0 m l ) , t h e c o m b i n e d e t h e r e a l s o l u t i o n was d r i e d (MgSOjj,), c o n c e n t r a t e d , a n d d i s t i l l e d u n d e r vacuum t o y i e l d 7 0 $ o f a p r o d u c t t h a t c o n t a i n e d E a n d Z i s o m e r s o f 22 i n a r a t i o o f 6 l » 3 9 a s d e t e r m i n e d b y v . p . c . F o r E - 3 3 1 i . r . 2 2 2 5 (G=N) a n d 1 6 2 5 cm" 1 ( C = C ) . F o r Z-22* i . r . 2 2 2 0 (C=N) a n d 1 6 1 0 cm""1 (C=C). The n.m.r. s p e c t r a w e r e c o n s i s t e n t w i t h t h o s e r e c o r d e d i n t h e l i t e r a t u r e ( 4 5 ) . 3 - M e t h o x y m e t h a c r y l o n i t r i l e , E- a n d Z- ( 3 4 ) S o d i u m m e t h o x i d e ( 1 e q u ) i n m e t h a n o l was a d d e d d r o p -w i s e , w i t h s t i r r i n g , t o 3 - b r o m o m e t h a c r y l o n i t r i l e (E and Z, - 1 1 3 -85*15) (1 e q u ) , s o d i u m b r o m i d e b e i n g i n s t a n t l y p r e c i p i t a -t e d . A f t e r c o m p l e t i o n o f t h e , a d d i t i o n , t h e s o l u t i o n was s t i r r e d f o r 2 h a t r o o m t e m p e r a t u r e . The s o l i d was r e m o v e d b y f i l t r a t i o n . The f i l t r a t e was n e u t r a l i z e d w i t h g l a c i a l a c e t i c a c i d a n d d i l u t e d w i t h e t h e r . R e m o v a l o f t h e w h i t e p r e c i p i t a t e , f o l l o w e d b y e v a p o r a t i o n o f t h e s o l v e n t u n d e r v a cuum, g a v e a n o i l y l i q u i d w h i c h was d i s t i l l e d u n d e r r e -d u c e d p r e s s u r e . The y i e l d o f t h e f i n a l p r o d u c t was 70$ w h i c h c o n t a i n e d E a n d Z i s o m e r s o f j i 4 i n a r a t i o o f 80:20 a s d e t e r m i n e d b y v . p . c . a n a l y s i s a n d c o m p a r i s o n o f t h e n.m.r. d a t a w i t h t h a t o f t h e l i t e r a t u r e ( 4 5 ) . E - 3 4 : b . p . 180-182°[lit. (88) b . p . 80-83/27 mm]; i . r . 2212 (CSN) and 1655 cm" 1 ( C = C ) . Z - 3 4 : b . p . 200-201* [ l i t . (45) b . p . 202-2 0 3 ° ] ; i . r . 2215 (C=M) and I658 cm" 1 ( C = C ) . P r e p a r a t i o n o f m e t h y l e t h y l k e t o n e c y a n o h y d r i n , (65) The m e t h o d d e s c r i b e d b y B a i l e y e t a l (89) was u s e d t o p r e p a r e t h e c y a n o h y d r i n 6 5 . One h u n d r e d grams (0 .97 m o l e ) o f p o w d e r e d s o d i u m c y a n i d e , 250 m l o f w a t e r , a n d 178 g (2.46 m o l e ) o f m e t h y l e t h y l k e t o n e w e r e p l a c e d i n a one l i t e r t h r e e - n e c k e d r o u n d b o t t o m f l a s k e q u i p p e d w i t h a mech-a n i c a l s t i r r e r , a d r o p p i n g f u n n e l , r e f l u x c o n d e n s e r , a n d a t h e r m o m e t e r . W h i l e t h e r e a c t i o n t e m p e r a t u r e was m a i n t a i n e d b e l o w 1 5 °and 4 2 0 m l (1 .7 m o l e ) o f 40$ s u l f u r i c a c i d was - 114 -b e i n g a d d e d o v e r a p e r i o d o f 3 h , t h e s o l u t i o n was v i g o r -o u s l y s t i r r e d . The o r g a n i c l a y e r was s e p a r a t e d , d r i e d (Na 2S0i},), a nd t h e e x c e s s m e t h y l e t h y l k e t o n e was r e m o v e d b y . d i s t i l l a t i o n . The r e s i d u e was d i s t i l l e d t h r o u g h a 1 2 " V i g r e u x c o l u m n t o y i e l d 35 g ( 8 0 $ ) o f t h e c y a n o h y d r i n 65» b . p . 9 8-100/ 2 5 mm [ l i t . (87) 108 . 4 / 4 0 mm]. 3 - M e t h y l m e t h a c r y l o n i t r i l e , E - a n d Z- (35) The d e h y d r a t i o n o f 6£ was done a c c o r d i n g t o H u r d a n d R e c t o r ' s (65) m e t h o d t o p r e p a r e E a n d Z i s o m e r s o f 3 - m e t h y l m e t h a c r y l o n i t r i l e . I n t o a t h r e e - n e c k e d f l a s k e q u i p p e d w i t h a m e c h a n i c a l s t i r r e r , r e f l u x c o n d e n s e r , and a d r o p p i n g f u n n e l was p l a c e d 99 g ( 1 . 0 m o l e ) o f t h e c y a n o -h y d r i n . C o l d 162 m l ( 2 . 0 m o l e ) o f a n h y d r o u s p y r i d i n e was a d d e d w i t h s t i r r i n g . T h i o n y l c h l o r i d e ( 2 . 0 m o l e ) was a d d e d d r o p w i s e t h r o u g h t h e d r o p p i n g f u n n e l . A f t e r t h e a d d i t i o n , t h e m i x t u r e was f u r t h e r s t i r r e d f o r 16 h a t 0°and was t h e n h e a t e d a t 80-90°for 3 h . W a t e r ( 1 0 0 m l ) was a d d e d t o t h e c o o l e d r e a c t i o n m i x t u r e . S u l f u r d i o x i d e was g i v e n o f f . A f t e r t h e a d d i t i o n o f more w a t e r a n d 10 m l o f 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 , t h e s o l u t i o n was e x t r a c t e d w i t h e t h e r (4 x 200 m l ) . The c o m b i n e d e t h e r s o l u t i o n was w a s h e d w i t h d i l u t e s o d i u m h y d r o x i d e s o l u t i o n t o n e u t r a l i z e a n y a c i d . T h e e t h e r s o l u t i o n was d r i e d (MgSOj^) f o r 4 h a n d t h e n f o r - 1 1 5 -3 h o v e r p h o s p h o r u s . p e n t o x i d e . F l a s h e v a p o r a t i o n o f t h e e t h e r g a v e a y e l l o w o i l y l i q u i d w h i c h was d i s t i l l e d b e t w e e n 122-140°to g i v e 57 g o f a c l e a r l i q u i d . T h i s was f o u n d t o c o n t a i n t h e E and Z i s o m e r s o f 21 i n a r a t i o o f 1 5 : 8 5 a s d e t e r m i n e d b y v . p . c . a n d n.m.r. a n a l y s e s . E - 3 5 : b . p . 136° [ l i t . ( 9 0 ) b . p . 138°]j i . r . 2 2 1 5 (C=N) a n d 1640 cm" 1 ( C = C ) . Z - l S i b . p . 1 2 2 " [ l i t . (90) b . p . 1 2 2 ° ] ; i . r . 2213 ( C s N ) and I 6 3 5 cm" 1 ( C = C ) . 1 - B r o m o p r o p e n e , E - a n d Z- (36) The i s o m e r i c b r o m o p r o p e n e s were o b t a i n e d b y t h e v . p . c . s e p a r a t i o n o f a c o m m e r c i a l ( A l d r i c h ) m i x t u r e o f b r o m o p r o p e n e s . The v . p . c . d a t a a l o n g w i t h t h e b o i l i n g p o i n t s a p p e a r i n T a b l e 6. 1 - C h l o r o p r o p e n e , E - a n d Z- (37) A m i x t u r e o f 1 - c h l o r o p r o p e n e s (K a n d K) was i n -j e c t e d i n t o v . p . c . t o o b t a i n t h e E a n d Z i s o m e r s . The v . p . c . d a t a a n d t h e b o i l i n g p o i n t s a p p e a r i n T a b l e 6 . 1 , 2 - D i b r o m o p r o p e n e , E- and Z- (38) The i s o m e r i c 1 , 2 - d i b r o m o p r o p e n e s were p r e p a r e d b y t r e a t i n g 70 g (0 .25 m o l e ) o f 1 , 2 , 2 - t r i b r o m o p r o p a n e (MCB) - 116 -w i t h 29 g (0 .25 m o l e ) o f s o d i u m p h e n y l a t e i n 20 m l o f e t h a n o l a t r e f l u x t e m p e r a t u r e ( 5 6 ) . A f t e r s i x h o u r s , t h e s o l i d s w e r e s e p a r a t e d a nd t h e E a n d Z i s o m e r s o f 38 w e r e s e p a r a t e d f r o m t h e a l c o h o l i c m i x t u r e b y v . p . c . The E:Z_ r a t i o was 7 0 O 0 ; t h e i s o m e r s h ad b o i l i n g p o i n t s c o r -r e s p o n d i n g t o t h e l i t e r a t u r e v a l u e s w h i c h a r e g i v e n i n T a b l e 6 . 1 , 2 - D i c h l o r o p r o p e n e , E- and Z- (39) 1 , 2 , 2 - T r i c h l o r o p r o p a n e (59 g» 0 .4 m o l e ) was t r e a t e d w i t h 27 g ( 0 . 4 m o l e ) o f s o d i u m , e t h o x i d e i n e t h a n o l a t 40° f o r 16 h ( 4 9 ) . The s o l u t i o n was d i s t i l l e d a n d t h e i s o m e r i c 1 , 2 - d i c h l o r o p r o p e n e s w e r e s e p a r a t e d b y v . p . c . The b o i l i n g p o i n t s o f t h e s e p a r a t e d i s o m e r s a r e c o r r e s p o n d i n g t o t h e l i t e r a t u r e v a l u e s a n d a r e g i v e n i n T a b l e 6 . 2 - B r o m o b u t e n e - 2 , E - a n d Z- ( 4 0 ) The E a n d Z i s o m e r s o f 4 0 w e r e s e p a r a t e d f r o m a c o m m e r c i a l l y a v a i l a b l e m i x t u r e o f b r o m o b u t e n e s b y v . p . c . The s e p a r a t e d i s o m e r s h a d b o i l i n g p o i n t s c o r r e s p o n d i n g t o t h e l i t e r a t u r e v a l u e s a n d a p p e a r i n T a b l e 6 . - 117 -2 - C h l o r o b u t e n e - 2 , E- a n d Z- ( 4 l ) S e p a r a t i o n b y v . p . c . was e f f e c t e d t o o b t a i n t h e E a n d Z i s o m e r s o f 4l_ f r o m a c o m m e r c i a l l y s u p p l i e d m i x t u r e o f c h l o r o b u t e n e s . E - 4 l i b . p . ?l°[lit. (55) b . p . 69-70°]. Z - 4 l : b . p . 62.5° [ l i t . (55) b . p . 62-62 .2°] . 1 - B r o m o - 2 - c h l o r o e t h y l e n e , E- a n d Z- ( 4 2 ) V i e h e ' s ( 6 4 ) p r o c e d u r e was u s e d t o o b t a i n t h e E a n d Z i s o m e r s o f 1 - b r o m o - l - c h l o r o e t h y l e n e . E q u i v a l e n t a m o u n t s o f 1 , 2 - d i b r o m o - and 1 , 2 - d i c h l o r o e t h y l e n e w e r e h e a t e d i n a s e a l e d t u b e a t 2 5 0 ° f o r 4 h . The p r o d u c t c o n -t a i n e d t h e t i t l e i s o m e r s i n e q u a l a m ounts (50$) b e s i d e s t h e a p p r e c i a b l e amounts o f t h e s t a r t i n g m a t e r i a l s . The i s o m e r s w e r e s e p a r a t e d b y v . p . c . a n d h a d t h e f o l l o w i n g b o i l i n g p o i n t s . E - 4 2 : b . p . 7 6 ° [ l i t . ( 6 2 ) b . p . 7 5 . 2 - . 4 ° ] . Z - 4 2 : b . p . 84° [ l i t . (62) b . p . 84. 5 - . 7 ° ] . 1 - B r o m o - l - c h l o r o p r o p e n e , E- (43) T h i s compound was p r e p a r e d a c c o r d i n g t o t h e p r o -c e d u r e o f H a t c h e t a l (63)0 B r o m i n e (0.22 m o l e ) was a d d e d t o a m i x t u r e o f 90$ t r a n s - a n d 10$ c i s - l - c h l o r o p r o p e n e ( 0 . 2 2 m o l e ) i n 200 m l o f c a r b o n t e t r a c h l o r i d e a t -10° t o -15° o v e r 1 h , f o l l o w e d b y s t i r r i n g f o r 3 h a t t h e same t e m p e r -- 118 -a t u r e . The s o l v e n t was re m o v e d u n d e r vacuum t o y i e l d a c l e a r l i q u i d , 42 g ( 8 0 $ ) o f 1 , 2 - d i b r o m o - l - c h l o r o p r o p a n e ( 6 6 ) . To 24 g (0.1 m o l e ) o f c r u d e d i b r o m i d e 66 was a d d e d 29 g ( 0 . 3 m o l e ) o f p o t a s s i u m a c e t a t e i n 75 m l o f a c e t i c a c i d . The r e s u l t a n t m i x t u r e was h e a t e d a t r e f l u x t e m p e r -a t u r e f o r 16 h , t h e s o l u t i o n t u r n e d b r o w n on w a r m i n g a n d became c h a r b l a c k a t t h e r e f l u x t e m p e r a t u r e . The m i x t u r e was c o o l e d , d i s s o l v e d i n 1 l i t e r o f w a t e r , a n d t h e o r g a n i c l a y e r was s e p a r a t e d . The a q u e o u s l a y e r was e x t r a c t e d w i t h e t h e r (3 x 100 m l ) . The e t h e r s o l u t i o n s w e r e c o m b i n e d , w a s h e d w i t h w a t e r (3 x 100 m l ) , a n d t a k e n i n a b e a k e r . S a t u r a t e d s o d i u m b i c a r b o n a t e s o l u t i o n was a d d e d t o n e u t r a l i z e a n y a c i d . The e t h e r l a y e r was s e p a r a t e d , d r i e d (MgSO^), c o n c e n t r a t e d , a n d d i s t i l l e d b e t w e e n 100 a n d 105°to y i e l d 1 2 g (35$) o f E-4_3_. L i t e r a t u r e (63) b . p . 33-3^/55 mm. The p r o d u c t g a v e o n l y one p e a k i n t h e v . p . c . w h i l e many c o l u m n s ( A p i e z o n - J , D i n o n y l P h t h a l a t e , DC - 5 5 0 , DIDP, FFAP, QF - 1 , a n d Se - 5 2 ) w e r e t r i e d . The n.m.r. f o r E - 4 3 i s § 1 . 7 5 ( d o u b l e t , 3 p r o t o n s , J = 7*0 H z ) and 6.11 ( q u a r t e t , 1 p r o t o n , J = 7.0 H z ) . 1 - B r o m o - l - c h l o r o p r o p e n e , Z_- (43) To 50 j l l s a m p l e s o f E-4J1 was a d d e d 2-3 ^61 o f a 10$ s o l u t i o n o f b r o m i n e i n c a r b o n t e t r a c h l o r i d e ( v / v ) . The s a m p l e s w e r e i r r a d i a t e d . The v . p . c . a n a l y s i s o f t h e - 119 -s a m p l e s i n d i c a t e d o n l y one p e a k i n t h e c h r o m a t o g r a m . B u t t h e p r e s e n c e o f Z-43 was d e t e c t e d i n t h e n.m.r. s p e c t r u m o f a n e q u i l i b r a t e d s a m p l e o f E-43. An a n a l y t i c a l s a m p l e o f t h e Z i s o m e r was p r e p a r e d b y p u t t i n g a n e q u i l i b r a t e d m i x t u r e o f E a n d Z i s o m e r s o f 4jt i n t o v . p . c . (20* x 1/4", 3 0 $ QP-1 on 45 / 6 0 Chrom. W, 80 m l p e r m i n , r e t e n t i o n t i m e ; E-4-3: 7 3 m i n , Z-4^; 7 4 m i n ) , s e p a r a t i n g , r e i n j e c t i n g , a n d s e p a r a t i n g a g a i n . The 99$ p u r e Z_ h a d b o i l i n g p o i n t o f 110-112° [ l i t . ( 6 3 ) b . p . 5 2-53 / 1 1 3 mm]. The n.m.r. i s t § 1 . 9 7 ( s i n g l e t , 3 p r o t o n s , J = 7»0 Hz) a n d 4 . 6 ( q u a r t e t , 1 p r o t o n , J = 7.0 Hz). 3 - C h l o r o a c r y l a m i d e , E- ( 6 7 ) A n h y d r o u s ammonia was b u b b l e d t h r o u g h a n i c e -c o o l e d a n d w e l l s t i r r e d s o l u t i o n c o n t a i n i n g 2 5 g (0.2 m o l e ) o f t h e E i s o m e r o f 3 - c h l o r o a c r y l o y l c h l o r i d e ( o b -t a i n e d b y t r e a t i n g E i s o m e r o f 3 - c h l o r o a c r y l i c a c i d w i t h p h o s p h o r o u s t r i c h l o r i d e ) i n 100 m l o f a n h y d r o u s e t h e r . A f t e r 3 0 m i n t h e e t h e r a n d e x c e s s ammonia w e r e e v a p o r a t e d a n d t h e s o l i d r e s i d u e was e x t r a c t e d w i t h e t h e r i n a S o x h -l e t e x t r a c t o r f o r 12 d a y s . On e v a p o r a t i o n o f t h e e t h e r e x t r a c t t h e r e was o b t a i n e d 1 7 g (70$) o f 62: m.p. 135-145° [ l i t . (91) m.p. 143.5-145"], n.m.r. (DMSO-dg) § 6.40 and 7 . 2 3 (2 d o u b l e t s , 1 p r o t o n e a c h , J = 13.0 Hz). - 120 -3 - C h l o r o a c r y l o n i t r i l e , E - and Z- (44) D e h y d r a t i o n o f 6_7_ was;done w i t h p h o s p h o r o u s p e n -t o x i d e (66). To a f l a s k c o n t a i n i n g 17 g (0.12 m o l e ) o f p h o s p h o r o u s p e n t o x i d e was a d d e d 10.5 g (0.1 m o l e ) o f E - 6 7 i n one o p e r a t i o n . The f l a s k was h e a t e d i n a n o i l b a t h m a i n t a i n e d a t 130-200°. A y e l l o w l i q u i d was c o l l e c t e d a s t h e m i x t u r e s t a r t e d t o d i s t i l l . The d i s t i l l a t e p a r t i a l l y s o l i d i f i e d i n t h e c o n d e n s e r , s o t h e c o n d e n s e r was h e a t e d b y b l o w i n g h o t a i r on i t s w a l l s t o s t o p c l o g g i n g . The f i n a l p r o d u c t c o n t a i n e d E a n d Z i s o m e r s o f 3 - c h l o r o a c r y l o -n i t r i l e i n a r a t i o o f 60s4o a s d e t e r m i n e d b y v . p . c . a n d n.m.r. a n a l y s e s ' . E-44: m.p. 45-46° [ l i t . (91) m.p. 45-46°] a n d Z-44: b . p . 145-146° [ l i t . (70) b . p . 145-146°]. 3 - B r o m o - 3 - b u t e n e n i t r i l e , (68) The t i t l e compound was p r e p a r e d a c c o r d i n g t o t h e p r o c e d u r e o f r e f e r e n c e 9 2 . S a t u r a t e d s a l t s o l u t i o n (1000 m l ) , c u p r o u s c y a n i d e ( 6 . 5 g ) , a n d a p i n c h o f c o p p e r p o w d e r w e r e i n t r o d u c e d i n t o a r o u n d b o t t o m f l a s k e q u i p p e d w i t h a r e f l u x c o n d e n s e r , a t w o way s t o p - c o c k , t h e r m o m e t e r , a n d a p a i r o f e l e c t r o d e s c o n n e c t e d t o a pH m e t e r . The s o l u t i o n was s t i r r e d w i t h a m a g n e t i c b a r and h e a t e d t o r a i s e i t s t e m p e r a t u r e t o 100°. H y d r o b r o m i c a c i d ( 6 . 5 m l ) was a d d e d , t h e n a s o l u t i o n o f s o d i u m c y a n i d e (53 g i n 160 m l o f w a t e r ) - 121 -was a d d e d t o b r i n g t h e pH v a l u e t o 2 . 8 , a n d t h e n 200 g ( 1 . 0 m o l e ) o f 2 , 3 - d i b r o m o p r o p e n e was a d d e d a t o n c e , a n d t h e m i x t u r e was r e f l u x e d . The a d d i t i o n o f s o d i u m c y a n i d e was m a i n t a i n e d a t a r a t e s o t h a t t h e pH o f t h e m i x t u r e r e m a i n e d b e t w e e n 2 . 5 - 2 . 8 ; t h e a d d i t i o n r e q u i r e d 12 h . The h e a t i n g w i t h s t i r r i n g was m a i n t a i n e d f o r a n o t h e r h o u r a n d t h e n t h e m i x t u r e was c o o l e d , e x t r a c t e d w i t h e t h e r , d r i e d (Na2S0£j,), c o n c e n t r a t e d , a n d d i s t i l l e d t o g i v e 98 g (67$) o f 3 - b r o m o - 3 - b u t e n e n i t r i l e : b . p . 65-66/20 mm [ l i t . (92) b . p . 62 - 6 3/17 mm]; i . r . 2 2 43 (C=N) a n d 1 6 3 0 c n r 1 ( C = C ) ; n.m.r. § 3•55 ( t r i p l e t , 2 p r o t o n s , J = 1 .3 H z ) , 5.73 ( m u l t i p l e t , 1 p r o t o n c i s t o B r , J = 1.3 H z ) , 6.10 ( m u l t i p l e t , 1 p r o t o n t r a n s t o B r , J = 1 .3 H z ) . T h i s n.m.r. s p e c t r u m i s c o m p a r a b l e t o t h e l i t e r a t u r e d a t a (93)» 2 - B u t y n e n i t r i l e , (69) V e s s i e r e a n d T h e r o n ' s (9*0 p r o c e d u r e was u s e d t o p r e p a r e 6£ b y s t i r r i n g 44 g ( 0 . 3 m o l e ) o f 3 - D r o m o - 3 - b u t e n e -n i t r i l e w i t h 16 g ( 0 . 4 m o l e ) o f s o d i u m h y d r o x i d e i n 250 m l o f w a t e r . The r e a c t i o n was k e p t c o o l b y e x t e r n a l c o o l i n g a n d s t i r r i n g c o n t i n u e d f o r 15-20 m i n u t e s . The s o l u t i o n was e x t r a c t e d w i t h e t h e r (3 x 200 m l ) , d r i e d ( N a 2 S 0 ^ ) , a n d t h e e t h e r was r e m o v e d u n d e r vacuum t o y i e l d 15 g (75$) o f a w h i t e s o l i d t h a t m e l t s a t room t e m p e r a t u r e : b . p . 115-120° [ l i t . (69) b . p . 108 - 1 0 9 / 7 3 5 mm]; i . r . 2263 (C=N) and - 122 -2239 cm- 1 (C=C); n.m.r.§ 2 .07 ( s i n g l e t ) . 3 - B r o m o c r o t o n o n i t r i l e , E - a n d Z- (45) T h e s e i s o m e r i c n i t r i l e s w e r e p r e p a r e d f r o m 6_2 b y t h e p r o c e d u r e o f V e s s i e r e a n d T h e r o n ( 6 7 ) . D r y h y d r o -b r o m i c a c i d g a s was b u b b l e d t h r o u g h a s o l u t i o n o f 13 g ( 0 . 2 m o l e ) o f 6£ i n 50 m l o f e t h e r o v e r a p e r i o d o f 2 h o u r s . The e x c e s s H B r was r e m o v e d b y p a s s i n g a s t r e a m o f d r y a i r j t h e e t h e r s o l u t i o n was d r i e d ( N a 2 S 0 ^ ) , c o n -c e n t r a t e d , a n d d i s t i l l e d (40-80/20 mm) t o y i e l d 15 g (51$) o f t h e f i n a l p r o d u c t t h a t was f o u n d t o c o n t a i n t h e E a n d Z i s o m e r s i n a r a t i o o f 30:70 f o r t h e n i t r i l e 45. E- 4 £ : i . r . 2207 ( C s N ) a n d 1608 cm" 1 (G=C). Z-4£ : i . r . 2212 ( C s N ) a n d 1620 cm" 1 ( C = C ) . 3 - C h l o r o c r o t o n o n i t r i l e , E- a n d Z- (46) E q u i v a l e n t amounts o f 2 - b u t y n e n i t r i l e (6_9_) a n d a q u e o u s H C l were s t i r r e d t o g e t h e r f o r 30 m i n u t e s ( 6 8 ) . The s o l u t i o n was e x t r a c t e d w i t h e t h e r , d r i e d ( N a 2 S 0 ^ ) , a n d t h e e t h e r was r e m o v e d u n d e r vacuum. The c o l o r l e s s l i q u i d was d i s t i l l e d u n d e r r e d u c e d p r e s s u r e t o y i e l d 46 t h a t was f o u n d t o c o n t a i n t h e E and Z_ i s o m e r s i n a r a t i o o f 1:9 a s d e t e r m i n e d b y v . p . c . a n a l y s i s . E-46: b . p . - 1 2 3 -1 2 2.5 - 1 2 3.5/ 7 3 0 mm ; i . r . 2 2 1 3 (C=N) and 1623 cm" 1 ( C = C ) . Z-46: b . p . 165-168°[lit. (68) b . p . 56 - 5 7 / 1 3 mm]; i . r . 2218 (C=N) and I 6 3 I cm" 1 ( C = C ) . 2 , 3 - D i c h l o r o a c r y l o n i t r i l e , E- and Z- (4£) To 4 7 . 3 g ( 0 . 3 m o l e ) o f 2,2,, 3 - t r i c h l o r o p r o p i o n i t r i l e ( C L B ) was a d d e d 1 3 g (0 .1 m o l e ) o f q u i n o l i n e ( 6 9 ) . The m i x t u r e was h e a t e d a t r e f l u x t e m p e r a t u r e f o r 18 h . The d a r k v i s c o u s l i q u i d was d i s t i l l e d , 125-132° [ l i t . (69) b . p . 1 3 0 - 1 3 1 ° ] , t o y i e l d 24 g ( 6 5 $ ) o f a c l e a r l i q u i d . The v . p . c . a n a l y s i s o f t h e p r o d u c t i n d i c a t e d o n l y one p e a k , b u t n.m.r. a n a l y s i s i n d i c a t e d two p e a k s a t § 7 . 3 2 and 7.07 w h i c h w e r e i n a r a t i o o f 7*3* P u r e s a m p l e s (90$) o f t h e E and Z i s o -m e r s w e r e p r e p a r e d b y v . p . c . ( 2 0 ' x 1/4", 3 0 $ QF-1 on 45/60 C h r o m . W, 80 m l p e r m i n , r e t e n t i o n t i m e ; Z: 28 m i n , Et 30 m i n ) . The n.m.r. s p e c t r a o f t h e s e p a r a t e d i s o m e r s c o r r e s -p o n d t o t h e ones r e p o r t e d i n t h e l i t e r a t u r e (66) a n d a r e g i v e n i n T a b l e 9* 2 , 3 - D i b r o m o p r o p i o n i t r i l e , (70) A q u a n t i t a t i v e y i e l d o f 2P_ was o b t a i n e d b y s l o w l y a d d i n g 320 g ( 2 . 0 m o l e ) o f b r o m i n e t o a w e l l s t i r r e d s o l u -t i o n o f 106 g ( 2 . 0 m o l e ) o f a c r y l o n i t r i l e i n 200 m l o f e t h e r . - 124 -The a d d i t i o n , c a t a l y z e d b y a fev/ i o d i n e c r y s t a l s , r e q u i r e d 2 . 5 h, a f t e r w h i c h t h e e t h e r was r o t a r y e v a p o r a t e d t o y i e l d 2 , 3 - d i b r o m o p r o p i o n i t r i l e w h i c h was u s e d a s s u c h f o r f u r t h e r r e a c t i o n s • 3 , 3 - D i m e t h o x y p r o p i o n i t r i l e , (71) S o d i u m m e t h o x i d e ( 2 . 0 m o l e ) i n 700 m l o f m e t h a n o l was a d d e d d r o p w i s e t o a s t i r r e d s o l u t i o n c o n t a i n i n g 213 g ( 1 . 0 m o l e ) o f 7_0 i n 120 m l o f m e t h a n o l . The a d d i t i o n was d o n e a t 0°. A f t e r t h e a d d i t i o n t h e r e a c t i o n m i x t u r e was a l l o w e d t o r e m a i n o v e r n i g h t a t room t e m p e r a t u r e . H e a t e d b r i e f l y a t r e f l u x t e m p e r a t u r e , 2 1 o f w a t e r was a d d e d , s a t u r a t e d w i t h s o d i u m c h l o r i d e , and e x t r a c t e d w i t h c h l o r o -f o r m (5 x 200 m l ) . The c o m b i n e d c h l o r o f o r m e x t r a c t s w e re w a s h e d w i t h w a t e r (2 x 50 m l ) , d r i e d (MgSO^), c o n c e n t r a t e d , a n d d i s t i l l e d u n d e r r e d u c e d p r e s s u r e t o y i e l d 8 0 . 5 g (70$) o f t h e n i t r i l e 21 ' o.p. 90-95/20 mm [ l i t . (70) b . p . 94-98/ 25 mm]; n.m.r. § 2.55 ( d o u b l e t , 2 p r o t o n s , J = 6 . 0 H z ) , 3 . 4 ( s i n g l e t , 6 p r o t o n s ) , a n d 4 .63 ( t r i p l e t , 1 p r o t o n , J = 6 . 0 H z ) . 3 - M e t h o x y a c r y l o n i t r i l e , E- a n d Z- (48) The a c e t a l 21 . (1.1*5 g# 0.1 m o l e ) was p l a c e d i n a b u l b t o b u l b d i s t i l l a t i o n a p p a r a t u s . F o u r d r o p s o f p h o s -- 1 2 5 -p h o r i c a c i d ( 8 5 $ ) were a d d e d t o t h e a c e t a l a n d t h e f l a s k was s h a k e n t o m i x t h e c o n t e n t s . The f l a s k was l o w e r e d i n t o a n o i l b a t h and t h e t e m p e r a t u r e was r a i s e d t o 1 7 5-180°and h e l d t h e r e f o r 0.5 h, d u r i n g w h i c h m e t h a n o l s t a r t e d t o d i s -t i l l . The t e m p e r a t u r e o f t h e b a t h v/as l o w e r e d t o 1 2 5 ° a n d t h e p r e s s u r e i n s i d e t h e f l a s k was r e d u c e d t o 20 mm a t w h i c h t i m e t h e p r o d u c t s t a r t e d t o d i s t i l l . The v . p . c . a n a l y s i s i n d i c a t e d t h e p r o d u c t , 4.2 g ( 5 0 $ ) , c o n t a i n i n g t h e E a n d Z i s o m e r s i n a r a t i o o f 6 0 : 4 0 . The i s o m e r s w e re s e p a r a t e d b y v . p . c . The n.m.r. r e s u l t s a p p e a r i n T a b l e 9. E - 4 8 t i . r . 2 210 ( C s N ) a n d 1 6 4 3 cm" 1 ( C = C ) . Z - 4 8 : i . r . 2208 (C=N) a n d 1 6 2 8 cm" 1 ( C = C ) . 3 , 3 - D i e t h o x y p r o p i o n i t r i l e , ( 7 2 ) S o d i u m e t h o x i d e ( 2 . 0 m o l e ) i n 6 0 0 m l o f e t h a n o l w as a d d e d d r o p w i s e , w i t h s t i r r i n g , o v e r a p e r i o d o f 3 h t o a s o l u t i o n o f 2 1 3 g ( 2 . 0 m o l e ) o f 2 , 3 - d i b r o m o p r o p i o -n i t r i l e (£0) i n 120 m l o f e t h a n o l a t 0°. A f t e r t h e a d d i -t i o n t h e r e a c t i o n m i x t u r e was a l l o w e d t o warm t o room t e m p e r a t u r e a n d h e l d t h e r e f o r 4 h , r e f l u x e d f o r 2 h , and c o o l e d . W a t e r (2 1) was a d d e d t o t h e r e a c t i o n m i x t u r e , s a t u r a t e d w i t h s o d i u m c h l o r i d e , a n d e x t r a c t e d w i t h c h l o r o -f o r m (5 x 2 5 0 m l ) . The c o m b i n e d c h l o r o f o r m e x t r a c t s w e r e w a s h e d w i t h w a t e r (2 x 1 0 0 m l ) , d r i e d (MgSO^), c o n c e n t r a t e d , - 1 2 6 -a n d d i s t i l l e d u n d e r r e d u c e d p r e s s u r e t o y i e l d 100 g (77$) o f t h e n i t r i l e £2: b . p . 104 - 1 0 7 / 2 0 mm [ l i t . (70) b . p . 57/ 1 mm, ( 9 5 ) b . p . 91-93.5/11 mm]; n.m.r. § 1.23 ( t r i p l e t , 6 p r o t o n s , J = 6 .0 H z ) , 2 . 5 5 ( d o u b l e t , 2 p r o t o n s , J = 6 .0 H z ) , 3 . 6 ( q u a r t e t , 4 p r o t o n s , J = 6 . 0 H z ) , a n d 4 .73 ( t r i p l e t , 1 p r o t o n , J = 6 .0 H z ) . 3 - E t h o x y a c r y l o n i t r i l e , E- a n d Z- (4£) To 20 g (0.14 m o l e ) o f 3 , 3 - d i e t h o x y p r o p i o n i t r i l e (72) was a d d e d 4 - 5 d r o p s o f p h o s p h o r i c a c i d ( 8 5 $ ) . The f l a s k was s h a k e n t o m i x t h e c o n t e n t s a n d l o w e r e d i n t o a n o i l b a t h , t h e t e m p e r a t u r e o f w h i c h was r a i s e d t o 170-180° a n d h e l d t h e r e f o r 0 . 5 h , d u r i n g w h i c h e t h a n o l s t a r t e d t o d i s t i l l . The t e m p e r a t u r e o f t h e b a t h was l o w e r e d t o 1 0 5 ° a n d t h e p r e s s u r e i n s i d e t h e f l a s k was r e d u c e d t o 20 mm. The p r o d u c t s t a r t e d t o d i s t i l l , 8 .2 g ( 6 0 $ ) , w h i c h c o n t a i n e d t h e E and Z_ i s o m e r s o f ^ i n a r a t i o o f 71*29 as d e t e r m i n e d b y v . p . c . a n d n.m.r. a n a l y s e s . The i s o m e r s were s e p a r a t e d b y v . p . c . E - 4 £ : b . p . 1 9 3 - 1 9 5 ° [ l i t . (70) b . p . 76-78/15 mm]; i . r . 2212 (CsN) a n d 1640 c m - 1 ( C = C ) . Z - 4 £ : b . p . 203-205° [ l i t . (70) b . p . 8 5 - 8 7 / 1 5 mm]; i . r . 2206 (C=N) a n d I625 cm"! ( C = C ) . - 1 2 7 -3 - E t h o x y m e t h a c r y l o n i t r i l e , E- ( j [ 0 ) S o d i u m e t h o x i d e ( 1 e q u ) i n e t h a n o l was a d d e d d r o p -w i s e , w i t h s t i r r i n g , t o t h e E i s o m e r o f 3 - b r o m o m e t h a c r y l o -n i t r i l e (_3_3_) ( 1 e q u ) , s o d i u m b r o m i d e b e i n g i n s t a n t l y p r e -c i p i t a t e d . The r e a c t i o n was c o o l e d b y e x t e r n a l c o o l i n g . ' A f t e r t h e a d d i t i o n , t h e m i x t u r e was l e f t s t i r r i n g a t room t e m p e r a t u r e f o r 2 h , t h e n n e u t r a l i z e d w i t h g l a c i a l a c e t i c a c i d a n d d i l u t e d w i t h e t h e r . The w h i t e p r e c i p i t a t e was r e m o v e d b y f i l t r a t i o n , t h e f i l t r a t e was c o n c e n t r a t e d a n d d i s t i l l e d u n d e r r e d u c e d p r e s s u r e t o y i e l d 60% o f E - 5 0 » b . p . 1 9 0 - 1 9 3 ° j i . r . 2 2 0 8 (CsN) a n d 1 6 5 0 cm" 1 ( C = C ) . A n a l . C a l c d f o r C 6 H Q N 0 : C, 6 4 . 8 6 ; H, 8 . 1 1 ; N, 1 2 . 6 1 . F o u n d : C, 6 4 . 6 0 ; H, 8 . 1 0 ; N, 1 2 . 8 3 . 3 - E t h o x y m e t h a c r y l o n i t r i l e , Z- ( 5 0 ) The p r o c e d u r e was t h e same a s t h a t u s e d f o r t h e p r e p a r a t i o n o f E-50 f r o m E~22> The y i e l d o f Z - 5 0 f r o m Z_-21 was 6 2 $ . The compound was p u r i f i e d b y v . p . c . a n d i t h a d t h e s e p r o p e r t i e s : b . p . 2 0 1 - 2 0 3 ° ; i . r . 2 2 1 2 ( C s N ) a n d 1 6 5 5 cm" 1 ( C = C ) . A n a l . C a l c d f o r C g H ^ O i C, 6 4 . 8 6 ; H, 8 . 1 1 ; N , 1 2 . 6 1 . F o u n d : C, 6 5 . 0 1 ; H, 8 . 0 4 ; N, 1 2 . 7 0 . - 128 -3 - I s o p r o p o x y m e t h a c r y l o n i t r i l e , E - a n d Z - (j5I) To a m i x t u r e o f t h e E a n d Z i s o m e r s (60:40) o f 33 (1 e q u ) was a d d e d , w i t h s t i r r i n g , s o d i u m i s o p r o p o x i d e (1 e q u ) i n i s o p r o p a n o l . S o d i u m b r o m i d e b e g a n t o p r e c i p i -t a t e . A f t e r t h e a d d i t i o n was c o m p l e t e , t h e r e a c t i o n m i x -t u r e was a l l o w e d t o r e m a i n s t i r r i n g f o r 1.5 h a t ro o m t e m p e r a t u r e . I t was t h e n n e u t r a l i z e d v / i t h g l a c i a l a c e t i c a c i d a n d d i l u t e d w i t h e t h e r . The w h i t e p r e c i p i t a t e was r e m o v e d b y f i l t r a t i o n , t h e f i l t r a t e was c o n c e n t r a t e d u n d e r v a c u u m , a n d t h e y e l l o w p r o d u c t was d i s t i l l e d u n d e r r e d u c e d p r e s s u r e t o g i v e a n o v e r a l l y i e l d o f 6 0 $ . The E a n d Z_ i s o -m e r s o f 51 p r e s e n t i n a r a t i o o f 53»47 w e r e s e p a r a t e d b y v . p . c . The s e p a r a t e d i s o m e r s h a d t h e s e p r o p e r t i e s : E-51» b . p . 198-199°; i . r . 2208 ( C s N ) a n d 1646 c m - 1 (C=rC). Z - ^ I J b . p . 209-210°; i . r . 2210 ( C s N ) a n d I650 cm" 1 ( C = C ) . A n a l . C a l c d f o r C ? H 1 : L N 0 J C, 6 7 . 2 0 ; H , 8 . 8 0 ; N, 1 1 . 2 0 , F o u n d f o r E : C, 67.28; H , 8.80; N, 11 .10. F o u n d f o r Z « C, 67.04; H , 9 . 0 5 ; N, 1 1 . 3 2 . 3 - t - B u t o x y m e t h a c r y l o n i t r i l e , E - a n d Z - (52) An E a n d Z m i x t u r e (60:40) o f 3 - b r o m o m e t h a c r y l o -n i t r i l e was t r e a t e d w i t h s o d i u m t - b u t o x i d e ( l t l ) i n t - b u t a n o l a t 35-40°and s t i r r i n g was m a i n t a i n e d . A f t e r 1 h - 129 -t h e m i x t u r e was n e u t r a l i z e d w i t h g l a c i a l a c e t i c a c i d a n d d i l u t e d w i t h e t h e r . A f t e r r e m o v a l o f t h e w h i t e p r e c i p i -t a t e , t h e f i l t r a t e was c o n c e n t r a t e d a n d d i s t i l l e d u n d e r r e d u c e d p r e s s u r e t o y i e l d a n o i l y l i q u i d f r o m w h i c h t h e E a n d Z i s o m e r s o f £2 w e r e s e p a r a t e d b y v . p . c . Et b . p . 199-201°j i . r . 2210 (C=N) a n d 1 6 4 5 cm" 1 ( C = C ) . Z» b . p . 206-207°; i . r . 2213 (C=N) a n d 1644 cm" 1 (C=C). Mass s p e c t r u m (E a n d Z) M + 139. 2 - B r o m o a c r y l o n i t r i l e , (73) P o t a s s i u m a c e t a t e (183 g» 1.87 m o l e ) i n 400ml o f a c e t i c a c i d a n d t h e c r u d e 2 , 3 - d i b r o m o p r o p i o n i t r i l e (70) ( 4 0 0 g, 1 .87 m o l e ) w e r e m i x e d a n d s t i r r e d a t room t e m p e r -a t u r e f o r 15 h ( 7 1 ) . Two l i t e r s o f w a t e r was a d d e d a n d t h e o r g a n i c l a y e r was s e p a r a t e d . The a q u e o u s l a y e r was e x t r a c t -e d w i t h e t h e r (5 x 100 m l ) a n d t r a n s f e r r e d t o a b e a k e r c o n -t a i n i n g 200 m l o f w a t e r . S o l i d s o d i u m b i c a r b o n a t e was a d d -e d w i t h s t i r r i n g . The a d d i t i o n c o n t i n u e d u n t i l t h e a q u e o u s l a y e r became n e u t r a l . The e t h e r l a y e r was s e p a r a t e d , d r i e d ( M gSO^), c o n c e n t r a t e d , a n d d i s t i l l e d t o y i e l d 138 g (60%) o f a l i g h t y e l l o w compound 21' °.p. 1 2 0 - 1 2 3 ° [ l i t . (96) 1167760 mm]; n . m . r . § 6.38 ( d o u b l e t , 1 p r o t o n , J = 2 .5 H z ) , 6 . 7 0 ( d o u b l e t , 1 p r o t o n c i s t o CN, J = 2 .5 H z ) . The n.m.r. s p e c t r u m i s c o n s i s t e n t w i t h t h e one r e c o r d e d i n t h e l i t e r a -- 130 -t u r e ( 9 7 ) . 3 - T h i o e t h o x y a c r y l o n i t r i l e , E- a n d Z- (53) T r i e t h y l a m i n e (10 g, 0.1 m o l e ) was a d d e d d r o p w i s e t o 12 g ( 0 . 0 9 m o l e ) o f 22 i n ^° m l o f e t h e r . The r e a c t i o n t e m p e r a t u r e was m a i n t a i n e d a t -78°. The s o l u t i o n t u r n e d b r o w n a n d became d a r k e r n e a r t h e end o f t h e a d d i t i o n . E t h a n e t h i o l ( 6 . 2 g, 0.1 m o l e ) was a d d e d t o t h e r e a c t i o n m i x t u r e o v e r a p e r i o d o f 0.5 h w h i l e s t i r r i n g was c o n t i n u e d . A f t e r t h e a d d i t i o n , t h e m i x t u r e was b r o u g h t t o ro o m t e m p e r -a t u r e a n d l e f t s t i r r i n g o v e r n i g h t . The s o l i d s w e r e r e m o v e d b y vacuum f i l t r a t i o n a n d t h e f i l t r a t e was c o n c e n t r a t e d ; a y e l l o w l i q u i d c o n t a i n i n g some s o l i d was o b t a i n e d . The s o l i d was r e m o v e d b y f i l t r a t i o n a n d t h e f i l t r a t e was d i s -t i l l e d u n d e r r e d u c e d p r e s s u r e , 92-95/1 mm [ l i t . (72) 111-115/18 mm], t o g i v e 4 . 4 g (43$) o f a c l e a r l i q u i d w h i c h was f o u n d t o c o n t a i n t h e E a n d Z i s o m e r s o f ^  i n a r a t i o o f 61:39 a s d e t e r m i n e d b y v . p . c . E: i . r . 2208 (C=N) a n d 1564 cm" 1 ( C = C ) . Z: i . r . 2210 ( C s N ) a n d 1560 cm" 1 ( C = C ) . 3 - T h i o e t h o x y m e t h a c r y l o n i t r i l e , E - and Z- (54) T h e s e compounds were p r e p a r e d a c c o r d i n g t o t h e p r o c e d u r e o f G a r d n e r a n d M c G r e e r (45)., T r e a t m e n t o f - 131 -3 - b r o m o m e t h a c r y l o n i t r i l e (22) c o n t a i n i n g E a n d Z i s o m e r s i n a r a t i o o f 60:40 w i t h s o d i u m t h i o x i d e (1:1) i n m e t h a n o l ( p r e p a r e d f r o m 1 equ o f s o d i u m m e t h o x i d e a n d 1.1 equ o f e t h a n e t h i o l ) y i e l d e d t h e c o r r e s p o n d i n g 3 - t h i o e t h o x y com-p o u n d s . The i s o m e r s w e re s e p a r a t e d b y v . p . c . E: b . p . 200-202° [ l i t . (45) b . p . 201-202°]. Z: b . p . 212-214° [ l i t . (45) b . p . 216-217°] . The n.m.r. d a t a f o r t h e s e p a r a t e d i s o m e r s a r e c o n s i s t e n t w i t h t h e l i t e r a t u r e v a l u e s (45) a n d a r e g i v e n i n T a b l e 9. 3 - B r o m o - 2 - m e t h y l - 2 - b u t e n o i c a c i d , E - (74) The m e t h o d g i v e n i n t h e l i t e r a t u r e (73) was u s e d t o p r e p a r e t h e bromo a c i d . To t i g l i c a c i d (100 g, 1 .0 m o l e ) i n 200 m l o f c a r b o n t e t r a c h l o r i d e was a d d e d 160 g ( 1 . 0 m o l e ) o f b r o m i n e d r o p w i s e , w i t h s t i r r i n g . The s o l u -t i o n was a l l o w e d t o s t a n d o v e r n i g h t , r e f l u x e d f o r 1 h , c o o l e d , a n d t h e s o l v e n t e v a p o r a t e d u n d e r vacuum t o y i e l d 222 g (86$) o f 2 , 3 - d i b r o m o - 2 - m e t h y l b u t y r i c a c i d . The c r u d e d i b r o m o a c i d (130 g, 0.05 m o l e ) was t a k e n i n t o a r o u n d b o t t o m f l a s k a n d t o t h i s was a d d e d 70 m l o f m e t h a n o l . To t h i s s o l u t i o n was a d d e d 700 g o f a 25$ s o l u t i o n o f p o t -a s s i u m h y d r o x i d e i n m e t h a n o l . A n h y d r o u s p o t a s s i u m c a r b o n -a t e (13 g) was a d d e d a nd t h e t e m p e r a t u r e o f t h e r e a c t i o n m i x t u r e was r a i s e d t o 55% where i t was h e l d f o r two h o u r s . - 1 3 2 -E x c e s s p o t a s s i u m h y d r o x i d e was r e m o v e d b y b u b b l i n g c a r b o n d i o x i d e t h r o u g h t h e s o l u t i o n . The m i x t u r e was f i l t e r e d w h i l e warm a n d w a s h e d w i t h 5 0 0 m l o f m e t h a n o l . The m e t h -a n o l s o l u t i o n s w e r e c o m b i n e d a n d t h e s o l v e n t was r e m o v e d u n d e r vacuum. The s o l i d r e s i d u e l e f t b e h i n d was d i s s o l v e d i n 1 0 0 m l o f w a t e r a nd a c i d i f i e d w i t h h y d r o c h l o r i c a c i d . The s o l i d p r o d u c t was s e p a r a t e d b y f i l t r a t i o n , d r i e d , a n d r e c r y s t a l l i z e d f r o m l i g r o i n t o y i e l d 5 6 . 4 g ( 6 3 $ ) o f t h e E i s o m e r o f 3 - b r o m o - 2 - m e t h y l - 2 - b u t e n o i c a c i d ( 2 4 ) 1 m.p. 9 3 - 9 4 " [ l i t . ( 7 3 ) m.p. 9 2 - 9 4 . 5 ° ] . P r e p a r a t i o n o f D i a z o m e t h a n e D i a z o m e t h a n e was p r e p a r e d f r o m N - n i t r o s o - N - m e t h y l u r e a a c c o r d i n g t o t h e p r o c e d u r e g i v e n b y C h i u ( 9 8 ) . M e t h y l 3 - b r o m o - 2 - m e t h y l - 2 - b u t e n o a t e , E- (j^5_) M e t h y l a t i o n o f £5_ w i t h d i a z o m e t h a n e gave t h e t i t l e e s t e r w h i c h was d i s t i l l e d t o y i e l d 9 5 $ o f E-j&t b . p . 7 0 - 7 3 / 1 8 mm [ l i t . ( 7 4 ) b c p . 7 5 - 7 6 / 2 0 mm]. The e s t e r was p u r i f i e d b y v . p . c . ( 1 0 * x 1 / 4 " , 1 5 $ QF - 1 + 5 $ C a r b o w a x 4 0 0 0 MS, 1 0 0 m l p e r m i n , r e t e n t i o n t i m e s 3,k m i n ) . The n.m.r. s p e c -t r a l v a l u e s a r e g i v e n i n T a b l e 1 1 . - 133 -M e t h y l 3 - b r o m o - 2 - m e t h y l - 2 - b u t e n o a t e , Z- (j5j5) S a m p l e s (50jJLl) o f E-55 w e r e s e a l e d i n P y r e x t u b e s (4 mm o.d.) a n d p l a c e d i n a f u r n a c e m a i n t a i n e d a t 210°. The d a r k e n e d s a m p l e s w e r e r e m o v e d a n d a n a l y z e d b y v . p . c . a n d n.m.r. w h i c h i n d i c a t e d t h e f o r m a t i o n o f Z-55 b e s i d e s t h e m a j o r p e r c e n t a g e o f t h e s t a r t i n g m a t e r i a l . The Z i s o m e r was s e p a r a t e d , t h e n.m.r. s p e c t r a l v a l u e s f o r w h i c h a p p e a r i n T a b l e 1 1 . A n a n a l y t i c a l s a m p l e c o n t a i n i n g t h e E a n d Z_ i s o m e r s o f j5£ i n a r a t i o o f 1:9 was p r e p a r e d f o r m i c r o a n a l y s i s . A n a l . C a l c d f o r C 6 H ^ B r 0 2 : C, 37.31; H, 4.66; B r , 41 . 45 . F o u n d : C, 37.34; H, 4.74; B r , 4 1 . 2 0 . M e t h y l 2 , 3 - d i b r o m o - 2 , 4 - d i m e t h y l p e n t a n o a t e , (75) The E a n d Z i s o m e r s o f m e t h y l 2 , 4 - d i m e t h y l - 2 -p e n t e n o a t e w e r e p r e p a r e d a c c o r d i n g t o t h e p r o c e d u r e o f C h i u a n d M c G r e e r (75). To a w e l l s t i r r e d s o l u t i o n o f t h e m e t h y l e s t e r s ( 1 4 . 2 g, 0.1 m o l e ) i n 50 m l o f c a r b o n t e t r a c h l o r i d e was s l o w l y a d d e d 16 g ( 0 . 1 m o l e ) o f b r o m i n e . T h e s o l u t i o n was s t i r r e d a n d a l l o w e d t o s t a n d o v e r n i g h t , a n d t h e n r e f l u x e d f o r one h o u r . The e x c e s s b r o m i n e was r e m o v e d b y s o d i u m b i s u l f i t e t r e a t m e n t . The p r o d u c t was e x t r a c t e d w i t h c h l o r o f o r m , d r i e d (MgSO^), and t h e s o l v e n t - 134 -was e v a p o r a t e d u n d e r vacuum t o y i e l d 83$ o f t h e d i b r o m o e s t e r 23J i»r. 1739 c m - 1 ( e s t e r C = 0 ) . T h i s was u s e d a s s u c h f o r t h e p r e p a r a t i o n o f t h e n e x t compound. M e t h y l 3 - b r o m o - 2 , 4 - d i m e t h y l - 2 - p e n t e n o a t e , E- a n d Z- ( 5 6 ) S o d i u m m e t h o x i d e ( 2 . 7 g» 0 . 0 5 m o l e ) i n 15 m l o f d r y m e t h a n o l was a d d e d d r o p w i s e t o a w e l l s t i r r e d s o l u -t i o n o f t h e c r u d e d i b r o m o e s t e r 25. (15*1 g» 0 . 0 5 m o l e ) ; t h e e x o t h e r m i c r e a c t i o n was c o n t r o l l e d b y e x t e r n a l c o o l i n g . The s o d i u m b r o m i d e w h i c h p r e c i p i t a t e d d u r i n g 2 h o f s t i r -r i n g was s e p a r a t e d b y f i l t r a t i o n . W a t e r (20 m l ) was a d d -e d t o t h e f i l t r a t e , t h e n e x t r a c t e d w i t h c h l o r o f o r m a n d d r i e d o v e r a n h y d r o u s m a g n e s i u m s u l f a t e . The s o l v e n t was r e m o v e d b y r o t a r y e v a p o r a t i o n and t h e l i q u i d d i s t i l l e d , 6 8 - 7 0/18 mm, t o y i e l d 13.3 g ( 6 0 $ ) o f a c l e a r , c o l o r l e s s , p l e a s a n t s m e l l i n g l i q u i d . The E a n d Z i s o m e r s o f ^6 w e r e s e p a r a t e d f r o m t h e p r o d u c t m i x t u r e b y v . p . c . ( 1 0 ' x 1/4", 15$ QF-1 + 5$ C a r b o w a x 4 0 0 0 MS on 60/80 Chrom. W, 170°, 1 2 0 m l p e r m i n ) . The a n a l y t i c a l s a m p l e s had t h e s e p r o p e r -t i e s : Ei r e t e n t i o n t i m e 4.0 m i n ; b . p . 155-157°; i . r . 1 7 25 ( e s t e r C=0) and 1 6 1 0 cm"*1 ( C = C ) . Z: r e t e n t i o n t i m e 6.0 m i n ; b . p . 165-168°; i . r . 1 7 35 ( e s t e r C=0) and 1 6 3 5 cm" 1 ( C = C ) . The n.m.r. d a t a f o r t h e i s o m e r s c a n be l o c a t e d i n T a b l e 1 1 . - 135 -A n a l . C a l c d f o r C 8 H 1 3 B r 0 2 : C, 4 3 . 4 4 ; H, 5 . 8 8 ; B r , 3 6 . 2 0 . F o u n d f o r E t C, 4 3 . 4 3 ; H, 5 .75? B r , 3 6 . 0 0 . F o u n d f o r Z i C, 4 3 . 5 1 ; H, 5 . 9 9 ; B r , 3 6 . 0 2 . P y r o l y s i s o f t h e E i s o m e r o f m e t h y l 3-bromo-2 , 4 - d i m e t h y l - 2 - p e n t e n o a t e (56) P y r o l y s i s o f t h e bromo e s t e r E - 5 6 a t 2 1 0 ° f o r 24 h i n s e a l e d t u b e s i n d i c a t e d t h e p r e s e n c e o f one m a j o r n o n -v o l a t i l e compound a s d e t e r m i n e d b y v . p . c . T h i s compound was s e p a r a t e d and i d e n t i f i e d a s 2 , 4 , 4 - t r i m e t h y l a n g e l i c a -l a c t o n e b y c o m p a r i s o n o f i t s p r o p e r t i e s w i t h t h o s e r e p o r t e d i n t h e l i t e r a t u r e ( 3 9 ) . The compound h a d a n m.p. o f 4 8 -4 9 . 5"i i . r . 1 7 5 4 ( c o n j u g a t e d l a c t o n e C=0) a n d I 6 7 2 cm" 1 ( C = C ) ; n.m.r. S 1*^3 ( s i n g l e t , 6 p r o t o n s a t C - 4 ) , 1 . 8 5 ( d o u b l e t , 3 p r o t o n s a t C - 2 , J = 1 . 4 H z ) , and 6 . 93 ( q u a r t e t , 1 p r o t o n a t C - 3 , J = 1 . 4 H z ) . A n a l . C a l c d f o r C y H 1 0 0 2 : C, 6 6 . 6 7 ; H, 7 . 9 3 . Founds C, 6 5 . 8 1 ; H, 7.24. M e t h y l 2 , 4 , 4 - t r i m e t h y l - 3 - h y d r o x y p e n t a n o a t e , ( 7 6 ) A t h r e e - n e c k e d r o u n d b o t t o m f l a s k e q u i p p e d w i t h a m e c h a n i c a l s t i r r e r , r e f l u x c o n d e n s e r w i t h d r y i n g t u b e , a n d a d r o p p i n g f u n n e l was c h a r g e d w i t h 500 m l o f a b s o l u t e - 136 -d r y e t h e r , 19.6 g ( 0 . 3 m o l e ) o f 30 mesh z i n c m e t a l , a n d a f e w c r y s t a l s o f i o d i n e . The e t h e r was r e f l u x e d f o r 0 . 5 h . The h e a t i n g was d i s c o n t i n u e d a n d a m i x t u r e o f 2 7 . 5 g (O . 3 2 m o l e ) o f p i v a l d e h y d e a n d 50.1 g ( 0 . 3 m o l e ) o f m e t h y l 2 - b r o m o p r o p i o n a t e was a d d e d d r o p w i s e o v e r a p e r i o d o f 2 h . The m i x t u r e was f u r t h e r r e f l u x e d w i t h s t i r r i n g f o r 4 h . W a t e r (300 m l ) was a d d e d t o t h e c o o l e d r e a c t i o n m i x t u r e . The w h i t e p r e c i p i t a t e was d e c o m p o s e d b y a d d i n g t h e n e c e s s a r y amount o f 20% s u l f u r i c a c i d . The s o l u t i o n was e x t r a c t e d w i t h e t h e r (3 x 200 m l ) a n d t h e c o m b i n e d e t h e r e a l s o l u t i o n was washed w i t h w a t e r , 5% s o d i u m b i c a r b o n a t e s o l u t i o n , a n d d r i e d o v e r a n h y d r o u s m a g n e s i u m s u l f a t e . The e t h e r was e v a p o r a t e d u n d e r vacuum a n d t h e r e m a i n i n g c l e a r l i q u i d d i s t i l l e d (120-150/50 mm) t o y i e l d 34 g (65%) o f t h e h y d r o x y e s t e r £ 6 . R e p e t i t i o n o f t h e a b o v e e x p e r i m e n t g a v e 80% y i e l d o f £6: n . m . r . § 0.93 ( s i n g l e t , 9 p r o t o n s ) , 1.18 ( d o u b l e t , 3 p r o t o n s o f m e t h y l a t C - 2 ) , 2 .60 ( m u l t i p l e t , 2 p r o t o n s o f C - 2 a n d OH), 3.48 ( m u l t i p l e t , 1 p r o t o n a t C - 3 ) , a n d 3 .63 ( s i n g l e t , 3 p r o t o n s o f m e t h y l e s t e r ) . M e t h y l 2 , 4 , 4 - t r i m e t h y l - 2 - p e n t e n o a t e , E- a n d Z- (££) To a m i x t u r e o f 8 .7 g ( 0 . 0 5 m o l e ) o f t h e h y d r o x y e s t e r £6 a n d 15.2 g (0 .058 m o l e ) o f t r i p h e n y l p h o s p h i n e was - 137 -a d d e d 150 m l o f c a r b o n t e t r a c h l o r i d e , a n d t h e s o l u t i o n was r e f l u x e d f o r a d a y . A f t e r r e f l u x i n g , t h e s o l u t i o n was s e p a r a t e d f r o m t h e s o l i d c a k e a nd t h e s o l v e n t s e v a p -o r a t e d u n d e r vacuum. The c o n c e n t r a t e d s o l u t i o n was t r e a t -e d w i t h p e t r o l e u m e t h e r a nd t h e w h i t e s o l i d p r e c i p i t a t e was r e m o v e d b y f i l t r a t i o n . The f i l t r a t e was c o n c e n t r a t e d a n d d i s t i l l e d , 7 5 - 8 0 / 2 0 mm, t o y i e l d 6 .3 g ( 8 0 $ ) o f a p r o d u c t t h a t was f o u n d t o c o n t a i n t h e E a n d Z_ i s o m e r s o f 52 in a r a t i o o f 74:26 a s d e t e r m i n e d b y v . p . c . a n d n.m.r. a n a l y s e s . The v . p . c . ( 1 0 ' x 1/4", 1 2 $ DC-550 + 8$ C a r b o w a x 4 0 0 0 MS o n 60/80 Chrom. W, 140°, 140 m l p e r m i n ) was u s e d t o s e p a r a t e t h e i s o m e r s . E - 5 7 : r e t e n t i o n t i m e 6.8 m i n ; b . p . 179-181° [ l i t . (76) b . p . 180.6°]; i . r . 1 7 2 0 ( e s t e r C=0) a n d 1645 cm" 1 ( C = C ) . Z - 5 7 : r e t e n t i o n t i m e 4.0 m i n ; b . p . 163-164° [ l i t . (76) b . p . 163 .2°] ; i . r . 1 7 4 0 ( e s t e r C=0) a n d 1660 cm" 1 ( C = C ) . 2 - 0 x 0 - 3 , 3 - d i m e t h y l b u t y r i c a c i d , ( 7 7 ) The p r o c e d u r e o f A n d e r s ( 9 9 ) was u s e d t o p r e p a r e 77» P i n a c o l o n e ( 2 0 g, 0.2 m o l e ) was a d d e d d r o p w i s e t o t h e s t i r r e d m i x t u r e o f 63 .2 g ( 0 . 4 m o l e ) o f p o t a s s i u m p e r m a n g a n a t e a n d 20 g ( 0 . 5 m o l e ) o f s o d i u m h y d r o x i d e i n 1*5 1 o f w a t e r . The e x o t h e r m i c r e a c t i o n was c o n t r o l l e d b y e x t e r n a l c o o l i n g a n d s t i r r i n g was c o n t i n u e d f o r 6 h . - 138 -The b r o w n M n 0 2 p r e c i p i t a t e was f i l t e r e d ( e x t r e m e l y d i f -f i c u l t t o f i l t e r ) . The f i l t r a t e was a c i d i f i e d w i t h h y d r o -c h l o r i c a c i d a n d e x t r a c t e d w i t h e t h e r (3 x 100 m l ) . The e t h e r e x t r a c t was d r i e d (MgSO^) a n d c o n c e n t r a t e d . The c o l o r l e s s l i q u i d o b t a i n e d was d i s t i l l e d u n d e r r e d u c e d p r e s s u r e , 60-63°/7 mm [ l i t . (97) b . p . 73.5-75/10 mm, (98) b . p . 8 0/15 mm ] t o y i e l d 35 g (95$) o f t h e a c i d 2 Z ! n.m.r. § 1 . 3 2 ( s i n g l e t , 9 p r o t o n s ) a n d 0.07 ( s i n g l e t , 1 p r o t o n ) . M e t h y l 2 - o x o - 3 , 3 - d i m e t h y l b u t a n o a t e , (£8) E s t e r i f i c a t i o n w i t h d i a z o m e t h a n e o f 22. g a v e a p r o d u c t w h i c h was d i s t i l l e d , 65-66/20 mm [ l i t . (100) b . p . 160-162] t o g i v e a q u a n t i t a t i v e y i e l d o f t h e k e t o e s t e r 78: n.m.r. § 1 .23 ( s i n g l e t , 9 p r o t o n s ) a n d 3.82 ( s i n g l e t , 3 p r o t o n s ) . M e t h y l 2 - e t h y l - 3 , 3 - d i m e t h y l - 2 - h y d r o x y b u t a n o a t e , (££) The e s t e r 22. w a s p r e p a r e d i n c o l l a b o r a t i o n w i t h D r . S. S z i l a g y i (76) o f t h i s l a b o r a t o r y . The k e t o e s t e r 78 (21.6 g, 0.15 m o l e ) was a d d e d t o a f l a s k c o n t a i n i n g 150 m l o f d r y e t h e r a n d e q u i p p e d w i t h a m e c h a n i c a l s t i r -r e r , r e f l u x c o n d e n s e r w i t h a C a C l 2 d r y i n g t u b e , a r u b b e r s e p t u m , a n d a n i t r o g e n a t m o s p h e r e . The r e a c t i o n m i x t u r e - 1 3 9 -was k e p t a t -78° ( d r y i c e - a c e t o n e b a t h ) and t o t h i s was a d d e d 5«^ g ( 0 . 1 5 m o l e ) o f e t h y l l i t h i u m ( 2 5 $ i n b e n z e n e ) w i t h t h e h e l p o f a s y r i n g e . A f t e r t h e a d d i t i o n t h e m i x -t u r e was b r o u g h t t o r oom t e m p e r a t u r e a n d p o u r e d i n t o a m i x t u r e o f i c e a n d 1 0 $ h y d r o c h l o r i c a c i d . The o r g a n i c l a y e r was s e p a r a t e d , washed w i t h w a t e r , a n d w i t h 5 $ s o d i u m b i c a r b o n a t e s o l u t i o n * a n d was d r i e d (MgSOj^). T h e s o l v e n t s w e r e r e m o v e d u n d e r vacuum a n d t h e y e l l o w l i q u i d o b t a i n e d was d i s t i l l e d , 8 0 -90/20 mm, t o y i e l d 1 0 g ( 4 0 $ ) o f 22.* b.p. 164-166°: n.m.r. § 0 . 9 3 ( s i n g l e t , 9 p r o t o n s ) , 3«77 ( s i n g l e t , 3 p r o t o n s o f m e t h y l e s t e r ) , 3.1 ( b r o a d s i n g l e t , 1 p r o t o n ) , 8 . 1 - 8 . 3 ( m u l t i p l e t , p r o t o n s o f C H Q ) , a n d 0.7 ( m u l t i p l e t o v e r l a p p e d w i t h s i n g l e t a t 0 . 9 3 * C H ^ p r o t o n s ) . The n.m.r. d a t a a r e i d e n t i c a l t o t h o s e g i v e n i n l i t e r a t u r e ( 7 6 ) . M e t h y l 2 - t - b u t y l - 2 - b u t e n o a t e , Z- ( 5 8 ) I n t o a 5°0 m l t h r e e - n e c k e d f l a s k was p l a c e d 17.4 g ( 0 . 1 m o l e ) o f t h e e s t e r 22.* T n e f l a s k was e q u i p p e d w i t h a m e c h a n i c a l s t i r r e r , a r e f l u x c o n d e n s e r , a n d a d r o p p i n g f u n n e l . The f l a s k was t h r o u g h l y c o o l e d i n a n i c e - b a t h a n d 0.2 m o l e o f a n h y d r o u s p y r i d i n e v/as a d d e d . T h r o u g h t h e d r o p p i n g f u n n e l , 0.2 m ole o f t h i o n y l c h l o r i d e was s l o w l y a d d e d w i t h v i g o r o u s s t i r r i n g . . The m i x t u r e t u r n e d d a r k - 140 -i m m e d i a t e l y a n d was k e p t s t i r r i n g f o r 12 h a t 0°and t h e n h e a t e d a t 8 0 - 9 0 °for 3 h . W a t e r (20 m l ) was a d d e d t o t h e c o o l e d s o l u t i o n . S u l f u r d i o x i d e was g i v e n o f f . 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 (5 m l ) was a d d e d t o t h e d a r k s o l u t i o n a n d e x t r a c t e d w i t h e t h e r . The e t h e r e a l s o l u t i o n was w a s h e d w i t h d i l u t e s o d i u m h y d r o x i d e s o l u t i o n u n t i l f r e e o f a c i d , d r i e d (Na 2S0i|,), a n d t h e s o l v e n t was r e m o v e d u n d e r v a c u u m t o y i e l d a c l e a r l i q u i d . The l i q u i d was d i s -t i l l e d u n d e r r e d u c e d p r e s s u r e ! b . p . 167-168°[lit. (76) b . p . 1 6 4 . 5 ] . The n.m.r. s p e c t r a l v a l u e s f o r Z - 5 8 a p p e a r i n T a b l e 11 . S o l v e n t b l a n k s S a m p l e s o f t h e i s o m e r s o f most o f t h e o l e f i n s f o r e q u i l i b r i u m s t u d i e s w e r e p r e p a r e d a s d e s c r i b e d i n t h e g e n -e r a l s t a t e m e n t s e c t i o n on p a g e 107, e x c e p t t h a t n o b r o m i n e ( c a t a l y s t ) was a d d e d . The s a m p l e s w e re i r r a d i a t e d a n d r e m o v e d f r o m t h e R a y o n e t a p p a r a t u s a t t h e same t i m e as t h e s a m p l e s c o n t a i n i n g t h e c a t a l y s t . The r a t e o f i s o m e r i z a t i o n i n t h e f o r m e r c a s e s was f o u n d t o be much s l o w e r t h a n i n t h e l a t t e r c a s e s . C o n c e n t r a t i o n e f f e c t s A s e r i e s o f s a m p l e s w i t h s o l u t e c o n c e n t r a t i o n s o f - 141 -1 0 , 5» 1» and 0 . 5 percent was prepared as described for the solvent studies. 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J o h n W i l e y a n d S o n s , New Y o r k , 1955. P. 7 3 1 . 7 2 . W.A. G r e g o r y a n d H.L. K l o p p i n g . U. S. P a t e n t No. 3 0 7 8 2 9 8 . F e b . 19, 1963; Chem. A b s t r . l493e ( 1 9 6 3 ) . 73. R.E. B u c k l e s a n d G.V. Mock. J . O r g . Chem. l j > , 680 (1950). 74. R.A. H o f f m a n a n d S. G r o n o w i t z . A r k i v . K e m i . 16, 471 ( i 9 6 0 ) . 75. D.E. M c G r e e r a n d N.W.K. C h i u . C a n . J . Chem. 46, 2 2 2 5 (1968). 7 6 . S. S z i l a g y i . Ph.D. T h e s i s . U n i v e r s i t y o f B r i t i s h C o l u m b i a , V a n c o u v e r , B.C., 1974. 77. H.M. M c N a i r a n d E . J . B o n e l l i . B a s i c Gas C h r o m a t o g r a p h y . C o n s o l i d a t e d P r i n t e r s , O a k l a n d , C a l i f . , 1967. p . 1 3 7 . 7 8 . A . L . M c C l e l l a n . T a b l e s o f E x p e r i m e n t a l D i p o l e Moments. W.H. F r e e m a n a n d Co., S a n F r a n c i s c o a n d L o n d o n , 1963* 79. R e f . 24. p . 460. 80 . J . T . E d w a r d . Chem. I n d . 1102 (1955). 8 1 . P. C a h i l l , L . P . G o l d , a n d N.L. Owen. J . Chem. P h y s . 48, 1620 (1968). 82. W.J. P o t t s a n d R.A. N y q u i s t . S p e c t r o c h i m A c t a . 6 7 9 (1959). 8 3 . E . L e w a r s , J . K . S t o w e l l , S. Wawzonek, a n d P. Y a t e s . Chem. I n d . 344 ( 1 9 6 8 ) . 84. K . L . R i n e h a r t , J r . a n d L . J . D o l b y . J . O r g . Chem. 22, 1 3 (1957). 8 5 . T. H a y a s h i , M. I g a r a s h i , S. H a y a s h i , a n d H. M i d o r i k a w a . B u l l . S o c . Chem. J a p a n , ^8, 2 0 6 3 ( 1 9 6 5 ) . 86. E.A. G u g g e n h e i m . T r a n s . F a r a d a y S o c . 4£, 714 (1949). 8 7 . A . E . F e r r i s a n d I.G. M a r k s . J . O r g . Chem. 1£, 1971 (1954). 88. J . G . L i c h t y . U. S. P a t e n t No. 2 384 1 0 6 . S e p t . 4, 1945; Chem. A b s t r . 40, 5 9 4 7 (1946). - 1 4 7 -8 9 . J.W. B a i l e y , F.E. N a y l o r , a n d J . J . H e w i t t . J . O r g . Chem. 22, 1076 (1957) . 9 0 . D i c t i o n a r y o f O r g a n i c Compounds. E y r e a n d S p o t t i s w o o d e L t d . , L o n d o n . V o l . 1, p . 239; V o l . 4 , p . 2161 (1965) . 9 1 . E . G r y s z k i e w i c z - T r o c h i m o w s k i , W. S c h m i d t , a n d 0 . G r y s z k i e w i c z - T r o c h i m o w s k i . B u l l . S o c . C h i m . F r . 593 (1948) . 9 2 . R. V e s s i e r e a n d F. T h e r o n . C. R. A c a d . S c i . P a r i s , 253, 676 (1961) . 93« R. V e s s i e r e a n d F. T h e r o n . B u l l . S o c . C h i m . F r . 299^ ( 1 9 6 8 ) . 9 4 . R. V e s s i e r e a n d F. T h e r o n . C. R. A c a d . S c i . P a r i s , 255, 3^24 ( 1962) . ; 9 5 . S.M. M c E l v a i n a n d R.L. C l a r k e . J . Amer. Chem. S o c . 6j9_, 2657 (1947) . 9 6 . H. B r i n t z i n g e r a n d A. S c h o l z . Chem. B e r . 8 J , 141 ( 1950) . 9 7 . V . S . W a t t s a n d J . H . G o l d s t e i n . J . Chem. P h y s . 4 2 , 228 ( 1965) . 9 8 . N.W.K. C h i u . M.Sc. T h e s i s . U n i v e r s i t y o f B r i t i s h C o l u m b i a , V a n c o u v e r , B.C., 1964. 9 9 . K. A n d e r s . A c t a . Chem. S c a n d . 2» 8 8 9 (1953) . 1 0 0 . R e f . 9 0 . V o l . 5» 3187 (1965) . 1 0 1 . C P . S m y t h . D i e l e c t r i c B e h a v i o r a n d S t r u c t u r e . M c G r a w - H i l l , New Y o r k , 1955. p . 233. - 148 -APPENDIX I D i s c c h a r t i n t e g r a t i o n m e t h o d t o c a l c u l a t e t h e p e r c e n t a g e s o f t h e i s o m e r s i n v . p . c . c h r o m a t o g r a m i s "both p r e c i s e a n d r a p i d . A nd t h e r e l a t i v e s t a n d a r d d e v i -a t i o n o f t h i s method f o r a g i v e n s a m p l e i s a p p r o x i m a t e l y 1.29$ a s r e p o r t e d b y M c N a i r a n d B o n e l l i (77). The d a t a i n T a b l e s 12 a n d 13 was e x p r e s s e d a s t h e a v e r a g e v a l u e arid one " i n s t a n t " s t a n d a r d d e v i a t i o n . The I.S.D. was c a l c u l a t e d b y m u l t i p l y i n g t h e r a n g e ( d i f -f e r e n c e b e t w e e n t h e l a r g e s t a n d t h e s m a l l e s t m e a s u r e -m e n t s ) b y a f a c t o r d e t e r m i n e d b y t h e number o f m e a s u r e -m e n t s made (77). The I.S.D.'s o f o l e f i n s c a l c u l a t e d b y t h i s m e t hod a r e i n c l u d e d i n T a b l e 17» a l o n g w i t h t h e r a n g e a n d number o f d e t e r m i n a t i o n s made f o r e a c h o l e f i n . A l t h o u g h v . p . c . was t h e m e t h o d m o s t u s e d f o r a n a l y s i s , i n s e p a r a t i o n o f i s o m e r s i n two o f t h e com-p o u n d s n e c e s s i t a t e d t h e u s e o f n.m.r. s p e c t r a l i n t e g r a -t i o n m e t h o d . T h i s m e t h o d i s l e s s p r e c i s e t h a n t h a t o f v . p . c . The b a s i c d i f f i c u l t y l i e s i n t h e i n t e r p r e t a t i o n o f t h e i n t e g r a l s o f p e a k s o f p a r t i c u l a r i n t e r e s t . The e q u i l i b r i u m v a l u e s o b t a i n e d b y t h i s m e thod w e r e g e n e r a l l y b a s e d on t r i p l i c a t e i n t e g r a l s o f t h e p e a k s . - 149 -T a b l e 17 " I n s t a n t " S t a n d a r d D e v i a t i o n s S u b s t i t u e n t s No. o f D e t e r m i n - Range O l e f i n C-1 C-2 S o l v e n t a t i o n s i n % E I.S.D. C C l ^ 6 0.6 0.2 22 CN,CH 3 C l P e n t a n e 6 1.8 0.7 N e a t 5 0.6 0.3 C C l ^ 5 1 .3 0.6 2 2 CN,CH 3 B r P e n t a n e 5 0.7 0.2 N e a t 4 2.3 0.9 C C l ^ 7 1.2 0.4 2 4 CN,CH 3 OCH^ P e n t a n e 4 0.5 0.2 N e a t 3 1.2 0.7 C C l ^ 5 1.7 0.7 21 CN,CH 3 CH^ P e n t a n e 6 1.0 0.4 N e a t 6 2.4 0.9 C C l ^ 7 0.6 0.2 36 B r CH^ P e n t a n e 5 1.4 0.6 N e a t 10 0.5 0.2 C C l ^ 7 1.3 0.5 2 7 C l CH P e n t a n e 6 0.8 0.3 3 N e a t 7 0.6 0.2 - 1 5 0 -T a b l e 1 ? ( c o n t i n u e d ) S u b s t i t u e n t s No. o f D e t e r m i n - Range O l e f i n C-1 C-2 S o l v e n t a t i o n s i n % E I.S.D. C C l ^ 4 0.8 0.4 J 8 B r B r . C H ^ P e n t a n e 4 0.8 0.4 N e a t 4 1.1 0.5 22 C l C 1 , C H 3 P e n t a n e 6 0.6 0.3 N e a t 4 1.0 0 . 5 C C l ^ 6 0.8 0.3 4 0 B r , C H 3 CH^ P e n t a n e 6 0.8 0.3 N e a t 8 0 . 5 0.2 4 1 C 1 , C H 3 CH^ P e n t a n e 6 0 . 5 0.2 N e a t 6 0 . 6 0.2 C C l ^ 3 0.4 0 . 3 4 2 C l B r P e n t a n e 5 0.5 0.2 N e a t 4 0 . 6 0 . 3 C C l ^ 4 1.1 0 . 5 4 4 CN C l P e n t a n e 6 1.1 0 .5 N e a t 6 0 . 6 0.2 - 1 5 1 -T a b l e 1 7 ( c o n t i n u e d ) S u b s t i t u e n t s No. o f D e t e r m i n - Range O l e f i n C - 1 C - 2 S o l v e n t a t i o n s i n % E I.S.D. C C l ^ 4 i . i 0 . 5 4£ CN B r . C H ^ P e n t a n e 4 1 .8 0 . 4 N e a t 4 1 . 3 0 . 6 C C l ^ 6 0 . 9 0 . 4 46 CN C l . C H ^ P e n t a n e 4 2 . 1 1 . 0 N e a t 4 2 . 0 1 . 0 C C l ^ 4 2.6 1 . 3 48 CN OCH^ P e n t a n e N e a t 6 1 . 8 1 . 5 C C l ^ 4 1 . 0 0 . 5 4_2 CN 0 C 2 H 5 P e n t a n e N e a t 4 2 . 0 1 . 0 C C l ^ 5 0 . 7 0 . 3 £ 0 CN,CH 3 0 C 2 H 5 P e n t a n e 5 1 . 9 0 . 8 N e a t 6 1 . 1 0 . 4 C C l ^ 5 0 . 8 0 . 3 5 1 CN,CH 3 O P r - i P e n t a n e 6 0 . 8 0 . 3 N e a t 4 0 . 3 0 . 1 - 1 5 2 -T a b l e 1 7 ( c o n t i n u e d ) S u b s t i t u e n t s No. o f D e t e r m i n - Range O l e f i n C - 1 C - 2 S o l v e n t a t i o n s i n % E I.S.D. C C l ^ 3 0 . 0 0 . 0 5 2 CN,CH 3 OBu-t P e n t a n e 4 0 . 7 0 . 3 N e a t 4 1 . 0 0 . 5 C C l ^ 5 0 . 4 0 . 2 2J. CN S C 2 H 5 P e n t a n e N e a t 4 0 . 5 0 . 2 CC1, 5 0 . 4 0 . 2 4 5 4 CN,CH_ SC H P e n t a n e 6 1 . 0 0 . 4 - A - 3 2 5 N e a t 6 1 . 3 0 . 4 - 153 -APPENDIX I I C a l c u l a t i o n o f D i p o l e Moments C a l c u l a t i o n s o f d i p o l e moments o f E and Z o l e f i n s a r e b a s e d o n t h e r u l e s o f v e c t o r a l g e b r a . The c a l c u l a t e d v a l u e s o f d i p o l e moments g i v e n i n T a b l e 14 w e r e o b t a i n e d b y t h e v e c t o r i a l a d d i t i v e m e t h o d f r o m g r o u p moments ( 8 ) . The m e t h o d o f c a l c u l a t i o n b y p r o j e c t i n g t h e v e c t o r o f a d i p o l e moment on a r b i t r a r i l y c h o s e n c o o r d i n a t e a x e s i s q u i t e c o n v e n i e n t . The d i p o l e moment i s o b t a i n e d a s t h e s q u a r e r o o t o f t h e sum o f t h e s q u a r e s o f t h e c o m p o n e n t sums m x, m y, a n d m z a l o n g e a c h a x i s , t h a t i s jJL = ( m x 2 + m y 2 + m z 2 ) * The p r o j e c t i o n o f a v e c t o r o f a d i p o l e moment o n t h e a p p r o p r i a t e a x i s i s composed o f t h e sum o f t h e p r o j e c t i o n s on t h i s a x i s o f t h e v e c t o r s o f a l l t h e g r o u p m o ments. The g r o u p moments u s e d i n t h e c a l c u l a t i o n s a r e f o r t h e g r o u p b o n d e d t o a n s p c a r b o n ( B e n z e n e , 2 5°C). The v a l u e s o f g r o u p moments a r e l i s t e d i n T a b l e 1 8 . I n t h e s e c a l c u l a t i o n s o f d i p o l e moments, b o n d a n g l e s o f 1 2 0 a r e a s s u m e d f o r t h e p l a n a r o l e f i n m o l e c u l e s . - 154 -T a b l e 18 G r o u p Moments G r o u p / ^ ( D ) b =C-CH 3 +0.37 = C-GN - 4 . 0 5 = G-G1 -1 .59 = C - B r - 1 . 5 7 = C-H 0.00 =C-OCH 3 +1.28 a The p o s i t i v e s i g n i s t a k e n f o r g r o u p s t h a t a r e p o s i t i v e p o l e s o f t h e d i p o l e . b I n Debye u n i t s . The m e t h o d o f c a l c u l a t i o n o f d i p o l e moments b y u s i n g g r o u p moments i s i l l u s t r a t e d on t h e n e x t p a g e . The d i s c r e p a n c i e s f o u n d b e t w e e n t h e c a l c u l a t e d a n d o b s e r v e d d i p o l e moments f o r t h e o l e f i n s o f T a b l e 14 c a n b e e x p l a i n e d b y t h e i n d u c t i v e a n d c o n j u g a t i v e e f f e c t s o f t h e d i p o l e s u p o n t h e g r o u p s ( 1 0 1 ) . - 1 5 5 -C a l c u l a t i o n of dipole moments of E - 3 3 and Z - 3 3 f o r E-jQ f o r Z-21 X X =c. -CH3 m x = - 0 . 3 7 C o s 6 0 my = + 0 . 3 7 S i n 6 0 =c--CN mx = - 4 . 0 5 my = 0 =c--Br mx = + 1 . 5 7 m y= 0 Cmx = - 2 . 6 6 5 Jm = +0 .32042 = [ ( - 2 . 6 6 5 ) 2 + (0 . 3 2 0 4 2 ) 2 1 1 / 2 2.684 D J =C' -CH3 -O . 3 7 C o s 6 0 m v = + 0 * 3 7 S i n 6 0 =c--CN m x = - 4 . 0 5 m y= 0 =C' -Br mx = - 1 . 5 7 C o s 6 0 m = + 1 . 5 7 S i n 6 0 ^mx = - 5 . 0 2 £ m y = +1.68 = [ ( - 5 . 0 2 ) 2 + ( 1 . 6 8 ) 2 ] 1 / 2 fJ. = 5 . 2 9 ^ D 

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