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UBC Theses and Dissertations

Thermal rearrangements of cis-2-alklcyclopropanecarboxylates and methyl 2-and 3-pentenoates Chiu, Norman Wing Kwai 1967

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T H E R M A L R E A R R A N G E M E N T S O F c i s -2 - A L K Y L C Y C L O P R Q P A N E C A R B O X Y L A T E S A N D M E T H Y L Z~ A N D 3 - P E N T E N O A T E S b y N O R M A N W I N G K W A I C H I U B . S c . (Honors C h e m , ) , D a l h o u s i e U n i v e r s i t y , 1962 M . S c , U n i v e r s i t y of B r i t i s h C o l u m b i a , 1964 A T H E S I S S U B M I T T E D IN 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 T H E D E G R E E O F D O C T O R O F P H I L O S O P H Y i n the D e p a r t m e n t of C H E M I S T R Y We accept this thes i s as c o n f o r m i n g to the r e q u i r e d s t a n d a r d 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 L A u g u s t , 1967" ' i n 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 of the requirements f o r an advanced degree at the U n i v e r s i t y of B r i t i s h Columbia, I agree t h a t the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e and Study. I f u r t h e r agree 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 copying of t h i s t h e s i s f o r s c h o l a r l y purposes may be granted by the Head of my Department or by h.i-s r e p r e s e n t a t i v e s . It i s understood t h a t copying or p u b l i c a t i o n of t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l not be a l l o w e d w i t h o u t my w r i t t e n p e r m i s s i o n . Department of CHEMISTRY The U n i v e r s i t y of B r i t i s h Columbia Vancouver 8, Canada Date September 12, I967 A B S T R A C T Seven a l k y l subs t i tu ted m e t h y l c y c l o p r o p a n e c a r b o x y l a t e s having an a l k y l g r o u p on C - 2 c i s to the e s t e r g r o u p have been found to r e a r r a n g e t h e r m a l l y to t h e i r c o r r e s p o n d i n g if, - u n s a t u -r a t e d e s t e r s at t e m p e r a t u r e s r a n g i n g f r o m 2 4 0 ° to 3 0 0 ° . The c o r -r e s p o n d i n g t r a n s i s o m e r s a r e unaf fec ted under i d e n t i c a l r e a c t i o n c o n d i t i o n s . It i s p r o p o s e d that the r e a r r a n g e m e n t takes p lace b y an i n t r a m o l e c u l a r 1 , 5 - h y d r o g e n t r a n s f e r v i a a s i x - m e m b e r e d c y c l i c t r a n s i t i o n state . The k i n e t i c s f o r these r e a c t i o n s have b e e n s t u d i e d and show f i r s t - o r d e r p lo ts w h i c h a r e l i n e a r to 70% r e a c t i o n . The heat of a c t i v a t i o n ( A H ) w a s found to be between 25 to 38 k c a l / mole and the e n t r o p y of a c t i v a t i o n ( A S ) w a s found to be between - 8 and - 3 7 eu. f r o m m e a s u r e m e n t s made o v e r a 2 0 ° range . T h i s and other i n f o r m a t i o n f u l l y s u p p o r t a c y c l i c h y d r o g e n t r a n s f e r m e c h a n i s m . F o u r m e t h y l c i s - 2 - p e n t e n o a t e s have been found to undergo both g e o m e t r i c and p o s i t i o n a l t h e r m a l i s o m e r i z a t i o n s to y i e l d e q u i -l i b r i u m m i x t u r e s of 2 - and 3-pentenoates at t e m p e r a t u r e s r a n g i n g f r o m 2 4 0 ° to 3 0 0 ° . The 3-pentenoates p r o d u c e d f r o m the c o r r e s -ponding t r a n s - 2 - p e n t e n o a t e s w e r e found to be f o r m e d v i a the c i s -2-pentenoate3. Studies u s i n g ^ - i s o p r o p y l a c r y l a t e and m e t h a c r y -late showed that the ra te of p o s i t i o n a l i s o m e r i z a t i o n w a s m u c h - i i i -f a s t e r than that of g e o m e t r i c i s o m e r i z a t i o n . F o r these s y s t e m s i t w a s t h e r e f o r e p o s s i b l e to s tudy the k i n e t i c s of the p o s i t i o n a l i s o m e r i s m i n the absence of compet ing g e o m e t r i c i s o m e r i z a t i o n , The k i n e t i c data p r o v i d e d f i r s t - o r d e r p l o t s . The heat of a c t i v a t i o n (AH**") w a s found to be between 18 and 38 k c a l / m o l e and the e n t r o p y of a c t i v a t i o n ( A S ) w a s found to be between - 8 to - 5 0 eu. A n i n t r a m o l e c u l a r 1 ,5 -hydrogen t r a n s f e r m e c h a n i s m i n v o l v i n g a s i x - m e m b e r e d c y c l i c t r a n s i t i o n state s i m i l a r to that f o r the c y c l o p r o p a n e s e r i e s i s i n d i c a t e d and i s suggested to be the g e n e r -a l m e c h a n i s m f o r c o n v e r s i o n of o ( ,p -unsaturated e s t e r s to |3,]f-u n s a t u r a t e d e s t e r s . The s e r i e s of 2 - a l k y l c y c l o p r o p a n e s have been p r e p a r e d b y the d e c o m p o s i t i o n of the c o r r e s p o n d i n g p y r a z o l i n e 3 . Some of these p y r a z o l i n e s have been n e w l y s y n t h e s i z e d f o r this w o r k and inc lude 1 m e t h y l 3 , 5 , 5 - t r i m e t h y l ~ 3 - c a r b o m e t h o x y - A - p y r a z o l o n e , m e t h y l 5 , 5 -d i m e t h y I - 3 - c a r b o m e t h o x y - A ^ - p y r a z o l i n e and 3, 5 - d i m e t b y l - 3 - c y a n o -A^ -pyrazolone . The d e c o m p o s i t i o n of p y r a z o l i n e s a l so y i e l d e d some of the ok.,fi> - u n s a t u r a t e d e s t e r s r e q u i r e d for this r e s e a r c h . S e v e r a l , h o w e v e r , have a l s o b e e n s y n t h e s i z e d b y the m o d i f i e d W i t t i g r e a c t -i o n . - i v -T A B L E O F C O N T E N T S I. I N T R O D U C T I O N 1 II. D I S C U S S I O N 1. P R E P A R A T I O N W O R K 13 Compounds s y n t h e s i z e d 13 P y r a z o l i n e method 13 M o d i f i e d W i t t i g r e a c t i o n 22 2. T H E R M A L R E A R R A N G E M E N T O F C Y C L O P R O P A N E S 26 T h e r m a l r e a r r a n g e m e n t of c y c l o p r o p a n es and i d e n t i f i c a t i o n of p r o d u c t s 26 K i n e t i c s tudies 32 D i s c u s s i o n of r e s u l t s 41 3. T H E R M A L I S O M E R I Z A T I O N O F O L E F I N S 52 T h e r m a l i s o m e r i z a t i o n of o le f ins and i d e n t i f i c a t i o n of p r o -ducts 52 K i n e t i c s tudies 64 D i s c u s s i o n of r e s u l t s 70 III. E X P E R I M E N T A L G e n e r a l s tatement 76 P r e p a r a t i o n of m e t h y l 1 , 2 , 2 - t r i m e t h y l - l - c y c l o p r o p a n e c a r b o x y -late 77 P r e p a r a t i o n of m e t h y l 2 , 2 - d i m e t h y l - l - c y c l o p r o p a n e c a r b o x y l a t e 80 P r e p a r a t i o n of c i s - and t rans -1.2 - d i m e t h y l -1 - c y a n o c y c l o p r o p a n e 82 P r e p a r a t i o n of m e t h y l c i s - and t r a n s - 2 , 4 - d i m e t h y l - 2 -pentenoate 84 P r e p a r a t i o n of m e t h y l c i s - and t r a n s - 4 - m e t h y l - 2 - p e n t e n o a t e 86 P r e p a r a t i o n of m e t h y l c i s - and £ranj>-2 - m e t h y l - 2 -pentenoate 88 P r e p a r a t i o n of m e t h y l jcis.- and t rana -2-pentenoate 89 T h e r m a l r e a r r a n g e m e n t of m e t h y l 1 , 2 , 2 - t r i m e t h y l - 1 - c y c l o p r o -p a n e c a r b o x y l a t e at 2 8 0 ° 90 T h e r m a l r e a r r a n g e m e n t of m e t h y l t rans -1 - m e t h y l - 2 - e t h y l -1 -c y c l o p r o p a n e c a r b o x y l a t e at 2 8 0 ° 91 T h e r m a l r e a r r a n g e m e n t of m e t h y l 2 , 2 - d i m e t h y l - 1 - c y c l o p r o -p a n e c a r b o x y l a t e at 2 5 8 ° 92 T h e r m a l r e a r r a n g e m e n t of t r a n s - 1 , 2 - d i m e t h y l - 1 - c y c l o p r o p a n e -c a r b o x y l a t e at 300 93 T h e r m a l r e a r r a n g e m e n t of t rans - 2 , 3 - d i m e t h y l - 1 - c y c l o p r o p a n e -c a r b o x y l a t e at 2 5 8 ° 93 T h e r m a l r e a r r a n g e m e n t of m e t h y l c i s -2 - m e t h y l - 1 - c y c l o p r o p a n e c a r b o x y l a t e at 2 9 4 ° 94 T h e r m a l r e a r r a n g e m e n t of m e t h y l c i s . t rans - 1 , 2,3 - t r i m e t h y l - 1 -c y c l o p r o p a n e c a r b o x y l a t e at 280 96 A t t e m p t e d t h e r m a l r e a r r a n g e m e n t of m e t h y l t r a n s - 2 - a l k y l - 1 -c y c l o p r o p a n e c a r b o x y l a t e s 96 A t t e m p t e d t h e r m a l r e a r r a n g e m e n t of c i s - and t r a n s - 1 , 2 - d i m e t h y l -1 - c y a n o c y c l o p r o p a n e at 258 97 K i n e t i c s tudies of the t h e r m a l r e a r r a n g e m e n t of c y c l o p r o p a n e s 97 P r e p a r a t i o n of m e t h y l 2, 4 - d i m e t h y l - 3 -pentenoate 99 P r e p a r a t i o n of m e t h y l 4 - m e t h y l - 3 - p e n t e n o a t e 100 P r e p a r a t i o n of m e t h y l t rans - 2 - m e t h y l - 3 - p e n t e n o a t e 100 P r e p a r a t i o n of m e t h y l _trans-3-pentenoate 101 T h e r m a l i s o m e r i z a t i o n , e q u i l i b r a t i o n and k i n e t i c s tudies of o le f ins 101 B I B L I O G R A P H Y 102 A P P E N D I X 108 - v i -L I S T O F T A B L E S Table Page I . 2 - A l k y I c y c l o p r o p a n . e s 1 4 II. &(, , J -Unsatura ted e s t e r s 1 4 I I I . P r o d u c t c o m p o s i t i o n f o r the m o d i f i e d W i t t i g r e a c t i o n 2 5 I V . N . M . R . data of m e t h y l c i s - and t r a n s - 2 - m e t h y l - 4 - h e x e n o a t e 2 9 V . K i n e t i c r e s u l t s of the t h e r m a l r e a r r a n g e m e n t of 2 - a l k y l -c y c l o p r o p a n e s 3 4 V I . T h e r m a l i s o m e r i z a t i o n of m e t h y l 2 , 4 - d i m e t h y l - 2 - and 3-pentenoate 5 7 V I I . T h e r m a l i s o m e r i z a t i o n of m e t h y l 4 - m e t i i y l - 2 ~ and 3-pentenoate 5 8 VII I . T h e r m a l i s o m e r i z a t i o n of m e t h y l 2 - m e t h y l - 2 - and 3 - pentenoate 5 9 IX . T h e r m a l i s o m e r i z a t i o n of m e t h y l 2 - and 3-pentenoate 6 0 X . K i n e t i c data of the t h e r m a l i s o m e r i z a t i o n of m e t h y l c i s -2 , 4 - d i m e t h y l - 2 - p e n t e n o a t e 6 9 X I . K i n e t i c data of the t h e r m a l i s o m e r i z a t i o n of m e t h y l c i s -4 - m e t h y l - 2 - p e n t e n o a t e 6 9 - V l l -L I S T O F F I G U R E S F i g u r e Page 1. N. M . R . s p e c t r u m of 3 , 5 - d i m e t h y l - 3 - c y a n o - Z l " - p y r a z o l i n e 21 2. P r o d u c t s of-the t h e r m a l r e a r r a n g e m e n t of c i s - 2 - a l k y l c y c l o -propanes 28 3. F i r s t - o r d e r rate plots for the t h e r m a l r e a r r a n g e m e n t of 32 35 4. F i r s t - o r d e r rate plots f o r the t h e r m a l r e a r r a n g e m e n t of 18, 33 and 35 36 5. F i r s t - o r d e r rate .p lo ts , far the t h e r m a l r e a r r a n g e m e n t of 36, 37_and38_ 37 6. A c t i v a t i o n plot f o r the t h e r m a l r e a r r a n ement of 32 38 7. A c t i v a t i o n plots f o r the t h e r m a l r e a r r a n g e m e n t of 18, 33 and 35 39 8. A c t i v a t i o n plots f o r the t h e r m a l r e a r r a n g e m e n t of 36, 37 and 38 40 9. P r o d u c t s f r o m the t h e r m a l i s o m e r i z a t i o n of c i s - 2 - p e n t e n o a t e s 55 10. E q u i l i b r a t i o n of m e t h y l 2 - and 3-pentenoates 61 11. F i r s t - o r d e r p l o t s ' f o r the t h e r m a l i s o m e r i z a t i o n of 42 65 12. F i r s t - o r d e r rate plots f o r the t h e r m a l i s o m e r i z a t i o n of 44 66 13. A c t i v a t i o n plot f o r the t h e r m a l i s o m e r i z a t i o n of 42 67 14. A c t i v a t i o n plot f o r the t h e r m a l i s o m e r i z a t i o n of 44 68 15. Double resonance N . M , R . s p e c t r u m of 43 79 1.6A. 100 M c . N . M . R . s p e c t r u m of m i x t u r e of 37 and 16 95 l o B . 100 M c . N . M . R . s p e c t r u m of 16 - V l l l A C K N O V / L E D G E M E N T The author w i s h e s to e x p r e s s h i s s i n c e r e a p p r e c i a t i o n to D r . D . E . M c G r e e r f o r h i s constant i n t e r e s t and e n c o u r a g e m e n t d u r i n g the c o u r s e of this r e s e a r c h and the p r e p a r a t i o n of th is t h e s i s . Thanks are extended to D r . R . E . P i n c o c k who r e a d and c o m m e n t e d on th is t h e s i s . The author i s indebted to M r s . A . B r e w s t e r , M i s s C . B u r f i t t and M r . R. . B u r t o n f o r the N . M . R . s p e c t r a , to D r . A B e r n h a r d t , M r s , C . J e n k i n s and M r . P . B o r d a f o r the m i c r o -a n a l y s e s . F i n a n c i a l a s s i s t a n c e f r o m the N a t i o n a l R e s e a r c h C o u n c i l and the U n i v e r s i t y of B r i t i s h C o l u m b i a i s g r a t e f u l l y a c k n o w l e d g e d . - 1 -I. I N T R O D U C T I O N R e c e n t l y a c o n s i d e r a b l e amount of w o r k has been done i n this l a b o r a t o r y c o n c e r n i n g the p y r o l y s i s of A ^ - p y r a z o l i n e s (1-7). T h i s r e -ac t ion has long been c o n s i d e r e d as a convenient synthet ic method for the p r e p a r a t i o n of c y c l o p r o p a n e d e r i v a t i v e s , and of o(,A- a n - d 0,Y~ unsatura ted o l e f i n s (8). H o w e v e r , our m a i n i n t e r e s t i n the p y r o l y s i s of c y c l o p r o p a n e s + o l e f i n s R = H , a l k y l . Y = C 0 2 R , C O R , C N A ^ - p y r a z o l i n e s has been to inves t igate the m e c h a n i s m of r i n g opening ' and p r o d u c t f o r m a t i o n . In,order to a c c o m p l i s h t h i s , the exact s t e r e o -c h e m i s t r y of not o n l y A ^ - p y r a z o l i n e s but a l so the p r o d u c t s of p y r o l y s i s has had to be d e t e r m i n e d . D u r i n g the c o u r s e of this i n v e s t i g a t i o n , d i f f i c u l t i e s w e r e encountered i n the a s s i g n m e n t of s t e r e o c h e m i s t r y to the c y c l o p r o p a n e d e r i v a t i v e s and <A,fi-unsaturated o l e f i n s . F o r e x a m p l e , n u c l e a r magnet i c resonance and i n f r a r e d data indicate the p r e s e n c e of a c y c l o p r o p a n e r i n g i n both c i s - and t r a n s - 1 , 2 - d i m e t h y l - 1 - a c e t y l c y c l o -propane (1 and 2)* but t h e i r s t e r e o c h e m i s t r y cannot be d e t e r m i n e d w i t h c e r t a i n t y (9). M o s t methods that have s u c c e s s f u l l y i d e n t i f i e d the s t e r e o -* A l l the d r a w n s t r u c t u r e s show c a r b o n - c a r b o n bonds ; each c o r n e r r e -p r e s e n t i n g a c a r b o n and the r e q u i r e d h y d r o g e n or hydrogens attached to it . are i m p l i e d . ' ' " " ^ C O M e 1 2 c h e m i s t r y of i s o m e r i c p a i r s make use of c o m p a r i s i o n s of the p r o p e r t i e s of the two i s o m e r s . It i s thus m o r e d i f f i c u l t i f o n l y one of the two i s o m e r s i s a v a i l a b l e ; f o r e x a m p l e , the exact s t e r e o c h e m i s t r y of one i s o m e r of m e t h y l 2, 3 - d i m e t b y l - 2 - p e n t e n o a t e (3) obta ined f r o m the p y r o l y s i s of 3, 4, 5 - t r i m e t h y l - 3 - c a r b o m e t h o x y - A ^ - p y r a z o l i n e (4) c o u l d not be d e t e r -m i n e d on the b a s i s of the data a v a i l a b l e (6) but w a s d e t e r m i n e d b y c o m -p a r i s o n w h e n the second i s o m e r w a s l a t e r obta ined (7). for the d e t e r m i n a t i o n of the s t e r e o c h e m i s t r y of c y c l o p r o p a n e s and oL unsatura ted o l e f i n s . These methods w i l l be d i s c u s s e d f i r s t , f o r the c y c l o p r o p a n e s and l a t e r for the c<,Q-unsaturated o l e f i n s . C 2 H 5 ( C H 3 ) C = C ( C H 3 ) C 0 2 M e + etc . 4 3 V a r i o u s c h e m i c a l and p h y s i c a l methods have been r e p o r t e d In 1890, B u c h n e r (10) a s s i g n e d the s t e r e o c h e m i s t r y to the two - 3 -c y c l o p r o p a n e - 1 - 2 - d i c a r b o x y l i c a c i d s on the b a s i s that on heat ing o r b y t rea tment w i t h a c e t y l c h l o r i d e , the c i s - i s o m e r (5) gave c y c l o p r o p a n e -anhydr ide (7) w h e r e a s the t r a n s i s o m e r (6) r e m a i n e d unchanged. C H 3 C O C l T h i s method w a s a lso u s e d for the a s s i g n m e n t of s t r u c t u r e for the t rans i s o m e r (8) of 3 - m e t h y l c y c l o p r o p a n e - 1 , 2 - d i c a r b o x y l i c a c i d o (11-1-3). The two c i s i s o m e r s (9 and 10) w i t h m e l t i n g points of 132 o and 108 both f o r m e d a n h y d r i d e s . O n l y one of these two c i s a c i d s , the ^CG2 H H 0 2 C -10 one m e l t i n g at 108 , w a s f o r m e d together w i t h the t rans i s o m e r (8) i n the r e a c t i o n of e thy l 2, 3 -d ibromobutanoate w i t h d i e t h y l malonate f o l -l o w e d b y comple te h y d r o l y s i s (11). W i t h the a s s u m p t i o n s that the d i -b r o m i d e w a s f o r m e d b y t rans addi t ion to m e t h y l t r a n s - c r o t o n a t e and that Sj^ 2 d i s p l a c e m e n t of both b r o m i n e s takes place on r i n g c l o s u r e , then 11 w o u l d be the i n t e r m e d i a t e (14) and o n l y ac ids w i t h t rans and _ 4 -CH_CHBrCHBrC0 0Et CHJCO,Et) NaOF.t 11 hydrolysis ^ C Q 2 H + cis acid,' (m.p. 108° H 0 2 C ' 8 (cis)-cis -configurati on would result (11). Thus the cis isomer with melting point 108° was assigned the structure (cis)-cis-3-methylcyclo -propane-1, 2-dicarboxylic acid (9) and the other with melting point 132° was assigned the structure (trans)-cis-3-methylcyclopropane-1, 2-di-carboxylic acid (10). cyclopropane -1-carboxylates (12 and 13) obtained by stereospecific ad-dition of carbomethoxycarbene to cis-butehe (15) was accomplished by the application of the principle of surface hindrance in catalytic hydro-genation (16). Addition of hydrogen being from the catalyst surface to the underside of the absorbed olefin in cis addition, the geometry of adsorption controls the stereochemistry of the product. In the case of methyl 1, 2-dimethylcyclopropene-3-carboxylate the favored con-figuration of adsorption leaves the methyl carboxylate group trans to the catalyst surface and leads to an all cis product, i . e. , methyl cis-Structural distinction between the two methyl cis-2, 3-dimetbyl-- 5 -i C H C Q 7 M e H 2 / P t 0 2 M e 14 12 2, 3 - d i m e t h y l c y c l o p r o p a n e - c i s -1 - c a r b o x y l a t e (12), thus 12 w a s d i f f e r -ent iated f r o m 13. A n o t h e r w a y to d i s t i n g u i s h i s o m e r i c c y c l o p r o p a n e c a r b o x y l i c ac ids i s to a p p l y c e r t a i n c h e m i c a l r e a c t i o n s to c o n v e r t the c i s i s o m e r to the m o r e stable t rans i s o m e r . T h e r e a r e two methods f o r the i n -v e r s i o n , one i s b y t r e a t i n g the c i s a c i d w i t h t h i o n y l c h l o r i d e (17) and the other i s to h y d r o l y z e the n i t r i l e o r a m i d e of the c i s a c i d w i t h e thanol i c p o t a s s i u m h y d r o x i d e (18). F o r e x a m p l e , c i s - 2 - m e t h y l c y c l o p r o p a n e c a r b o x -amide (15) w a s c o n v e r t e d b y h y d r o l y s i s to the t r a n s - 2 - m e t h y l c y c l o p r o p a n e -15 16 - 6 -c a r b o x y l i c a c i d (16) (19). U n d e r the base condi t ions the anion at the o{-C i s p r e s u m a b l y f o r m e d p e r m i t t i n g i n v e r s i o n w h i c h on e q u i l i b r a t i o n g i v e s the m o r e stable t r a n s f o r m . C o m p e t i t i v e s a p o n i f i c a t i o n of i s o m e r i c e s t e r s of c y c l o p r o p a n e -c a r b o x y l i c a c i d s has a lso been u s e f u l for s t r u c t u r a l d i s t i n c t i o n . The rate of s a p o n i f i c a t i o n of m e t h y l c i s - 1 , 2 - d i m e t h y l c y c l o p r o p a n e - 1 - c a r b o x y l a t e (17) i s found to be f a s t e r than i ts t rans i s o m e r (18) p r e s u m a b l y due to the fact that the es ter m o i e t y of c i s i s o m e r (17) i s l e s s h i n d e r e d s t e r i c a l l y (20). The use of s p e c t r o s c o p i c methods for the d e t e r m i n a t i o n of I s t e r e o c h e m i s t r y o f c y c l o p r o p a n e d e r i v a t i v e s has been l i m i t e d to n u c l e a r magnet i c r e s o n a n c e . T h i s i s m a i n l y due to the l a c k of u s e f u l I | i n f o r m a t i o n f r o m i n f r a r e d and u l t r a v i o l e t a d s o r p t i o n s of c y c l o p r o p a n e I d e r i v a t i v e s . R e c e n t l y , a c o n s i d e r a b l e attention has been devoted to | the i n f r a r e d study of c y c l o p r o p a n e compounds (21 and r e f e r e n c e s j there in) but the purpose w a s l i m i t e d to the detect ion of the c y c l o p r o -l pane r i n g i n m o l e c u l e s . F a r k a s and c o w o r k e r s (22) and V e l d s t r a (23) I | at tempted to a s s i g n g e o m e t r i c c o n f i g u r a t i o n to 2 - p h e n y l c y c l o p r o p a n e -- 7 -c a r b o x y l i c ac id s and t h e i r 3 - a l k y l subst i tuted analogues w i t h l i t t l e s u c -c e s s . The d i f f e r e n c e s i n u l t r a v i o l e t c u r v e s f o r these i s o m e r i c p a i r s of ac ids have been found to be r e l a t i v e l y s m a l l , e . g . , t rans -2 - p h e n y l c y c l o -p r o p a n e c a r b o x y l i c a c i d (19) a b s o r b s - a t l o n g e r w a v e l e n g t h (by 6. 5 laryU) then i ts c i s i s o m e r (20). These s p e c t r a l m e a s u r e m e n t m a y b e r e g a r d e d 1_9_ , • 20 l o g & = 2. 56 log £ =2 . 33 X m a x = 266.5 mjl X m a x = 260 rajx as u s e f u l o n l y i f s p e c t r a of both i s o m e r s a r e a v a i l a b l e . N u c l e a r magnet i c resonance spec t ro scopy has . been u s e d w i d e l y i n r e c e n t y e a r s f o r the s t r u c t u r a l d e t e r m i n a t i o n of subst i tuted c y c l o p r o -panes . The c o u p l i n g constants and c h e m i c a l shi f ts of a l a r g e n u m b e r s of subst i tuted c y c l o p r o p a n e s have been d e t e r m i n e d r e c e n t l y (24-27). T h e r e are s e v e r a l i m p o r t a n t f indings w h i c h can be used to d e t e r m i n e the g e o m e t r y of subst i tuted c y c l o p r o p a n e s . The f i r s t of these i s that the c i s v i c i n a l p r o t o n - p r o t o n c o u p l i n g constant i s g r e a t e r than the t r a n s i n c y c l o p r o p a n e s (23-24). The second i s that both c i s and t r a n s c o u p l i n g constants are r e l a t i v e l y i n s e n s i t i v e to the nature of subst i tuents , t h e i r values are between +8.0 to +11.2 c .p . s . " and +5.2 to +8.0 c . p . s . for c i s and t r a n s protons r e s p e c t i v e l y . A n d the t h i r d i s that the c h e m i c a l - 8 -shifts are strongly influenced by the nature of the substituents on the ring, especially, magnetically anisotropic species, such as a phenyl or a carbonyl group. The spectrum of cyclopropane -1, 1,2-tricarboxylic acid (21) showed a large cis (H -H ) coupling " A -A. constant of 9.33 c.p.s. and a smaller trans (H - H v ) of 6.55 c.p.s. The Chemical shifts of H A and are 7.70 T and 7.58 • respec-tively. The reason that H_ appears at lower field than H is because B A there are two carboxvlic group cis to whereas there is only one cis to HL^  and consequently, is more deshielded by the anisotropy of the carboxyl group. Recently, McGreer and coworkers (6) assigned configuration to methyl cis,cis- and cis,trans -1,2,3-trimethylr 1-cyclo-propanecarboxvlate (22 and 23) based on symmetry consideration and the anisotropic influence on chemical shifts. In 22, there is a plane of 21 22 23 - 9 -symmetry with respect to C-2 and C-3, thus the C-2 and C-3 methyls are equivalent and appear as a doublet at 9.07 f which is split by a ring proton at 8.5 9 T. On the other hand, the C-2 and C-3 methyls in 23 are non-equivalent because the former is cis to the carbomethoxy group whereas:the latter is trans to the same and as a result, the C-2 methyl-shows a doublet at 8.91 T and the C-3 methyl shows a doublet at 8.94 X-The 8.91 'T peak is split by a ring hydrogen trans to the carbomethoxy group at 9.37 T. The 8.94 X peak is split by the hydrogen cis to the carbomethoxy group at 8.61 T . Clearly this chemical shift is markedly affected by the anisotropy of the carbomethoxy group but that of the cis ring methyl is not. This is in contrast to observations on the c(>y3~ unsaturated carbonyl derivatives described below. Methods for the structural determination of {^,^3-unsaturated olefins have rarely been studied. Sudborougb and Davies (28) studied the rates of esterification of angelic (24) and tiglic (25) acids and V _ _ / / C 0 2 H ^Z00^ \ r~\ 24 25 found that the former is esterified slower due to the steric effect of the methyl cis to the carboxylic group. Infrared spectroscopy is very useful for configurational analysis of a(,fi>-unsaturated olefins. For the isomeric disubstituted - 10 -o l e f i n s (29), 26 shows two bands , one at 1415 c m " ^ due to C ^ H i n -plane bending and the other at 730-675 c m ~ ^ due to C - H o u t - o f - p l a n e bending. On the other hand 27 shows o n l y one band at 965 cm"^ due to C - H o u t - o f - p l a n e b e n d i n g . F o r s y s t e m s that are t r i - o r t e t r a - s u b s t i -\ = / * / R = a l k y l , a r y l g Y = C 0 2 H : C O z R 26 27 C O R > C N tuted, the use of i n f r a r e d s p e c t r o s c o p y i s l i m i t e d because there a r e no i n f r a r e d bands w h i c h can be r e l i a b l y c o r r e l a t e d w i t h c o n f i g u r a t i o n s . D u r i n g the past few y e a r s the a p p l i c a t i o n of n u c l e a r magnet i c resonance s p e c t r o s c o p y to the a s s i g n m e n t of c o n f i g u r a t i o n s of c\,^-un-sa tura ted o l e f i n s has ; p r o v e n v e r y s u c c e s s f u l . T h i s method can d e t e r m i n e the c o n f i g u r a t i o n of not o n l y m o n o - and d i - but a l so t r i - and t e t r a -subst i tuted o l e f i n s . The m o s t i m p o r t a n t i n f o r m a t i o n i s that anyci ' s ^>-vinyl proton or pro ton on the f i r s t c a r b o n of an a l k y l group attached to the ^3-carbon c i s to a d i a m a g n e t i c a n i s o t r o p i c g r o u p , such as a c a r b o n y l group, w i l l be de s h i e l d e d w i t h r e s p e c t t o the trans' a r r a n g e m e n t (30):. The p r o t o n - p r o t o n c o u p l i n g constants for v i n y l protons a c r o s s the double bond are e s p e c i a l l y v a l u a b l e f o r the i s o m e r i c v i c i n a l d i subs t i tu ted o le f ins because the c i s c o u p l i n g constant has been found to be s m a l l e r than the t r a n s coupl ing constant (31-33). F o r e x a m p l e , the c o u p l i n g constants ( H C = C H ) for m e t h y l c i s - and t r a n s - c r o t o n a t e (28 and £ 9 ) - 11 -\ y C C ^ M e y C 0 2 M e 28 29 are 11.4 c . p . s . and 15.5 c . p . s . r e s p e c t i v e l y , as d e t e r m i n e d b y the A B X ^ t r e a t m e n t of Wau-gh and F e s s e n d e n (33) and b y f i r s t - o r d e r p e r t u r b a t i o n t h e o r y a n a l y s i s (31). The C - 3 m e t h y l appears at l o w e r f i e l d b y 0.26 TT units f o r the c i s i s o m e r w h e r e a s i ts C - 3 h y d r o g e n appears at h i g h e r f i e l d b y 0.62 <-( uni ts than those of the t r a n s i s o m e r . These ef fects a r e due to the a n i s o t r o p i c ef fect of the c a r b o m e t h o x y g r o u p . J u d g i n g f r o m the e x a m p l e d e s c r i b e d above, i t i s p o s s i b l e but s o m e t i m e s r i s k y to d e t e r m i n e the s t r u c t u r e w i t h c e r t a i n t y i f o n l y one of the i s o m e r s i s p r e s e n t . B o t h i s o m e r s are r e q u i r e d f o r c o m p a r i s o n p u r -poses. The p r e s e n c e of both i s o m e r s w i l l then r e n d e r i t p o s s i b l e f o r the d e t e r m i n a t i o n of the s t r u c t u r e w i t h c e r t a i n t y . H o w e v e r , i t i s of value to s e a r c h f o r another method w h i c h can serve the same p u r p o s e w h e n o n l y one of the i s o m e r s i s p r e s e n t . R e c e n t l y , we have o b s e r v e d (34) a n o v e l r e a c t i o n i n w h i c h a c i s - 2 - a l k y l c y c l o p r o p a n e c a r b o x y l a t e , e . g . 18, r e a r r a n g e s t h e r m a l l y to g ive e x c l u s i v e l y a Y, ©"-unsaturated es ter (31) w h e r e a s the t r a n s i s o m e r (17) r e m a i n s unchanged under i d e n t i c a l r e a c t i o n c o n d i t i o n s . A m e c h a n i s m p r o p o s e d for this t h e r m a l r e a r r a n g e m e n t w a s that i t i n v o l v e s an a l l y l i c - 12 -M e enol i n t e r m e d i a t e 30. T h i s p r o p o s e d i n t e r m e d i a t e i s analogous to the a l l y l i c enol i n t e r m e d i a t e p r o p o s e d f o r the p h o t o i s o m e r i z a t i o n of c r o t o n -aldehyde to 3 - b u t e n - l - a l (35) and of o(,^>-unsaturated ketones to 0,H-u n s a t u r a t e d ketones (36b- D u r i n g the c o u r s e of th is r e s e a r c h , o ther l a b o r a t o r i e s have i n v e s t i g a t e d v a r i a t i o n s of this r e a c t i o n and these a r e p r e s e n t e d i n the d i s c u s s i o n . T h i s t h e r m a l r e a r r a n g e m e n t of c i s - 2 - a l k y l c y c l o p r o p a n e -c a r b o x y l a t e s is. p o t e n t i a l l y va luable f o r s t r u c t u r a l d e t e r m i n a t i o n not o n l y of c y c l o p r o p a n e d e r i v a t i v e s but a lso of cK,^3-unsaturated o l e f i n s . It i s the p u r p o s e of this r e s e a r c h to inves t igate the s t e r e o c h e m i c a l aspect of this r e a r r a n g e m e n t r e a c t i o n and to extend i t to the oC/3-un-sa tura ted e s t e r s i n the hope that a convenient and accura te method of c o n f i g u r a t i o n a l a n a l y s i s can be found f o r these c o m p o u n d s . - 13 -II. D I S C U S S I O N II-I P R E P A R A T I O N W O R K Com pou nds s y n t h e s i z e d F o r the p r e s e n t study, a s e r i e s of 2 - a l k y l c y c l o p r o p a n e s w i t h an e l e c t r o n w i t h d r a w i n g group s u c h as c a r b o m e t h o x y , a c e t y l o r cyano at C - l and a s e r i e s of subst i tuted c i s - and . i r a n s - u n s a t u r a t e d e s t e r s w e r e r e q u i r e d . These c y c l o p r o p a n e s can be p r e p a r e d b y the d e c o m p o s i -t ion of the c o r r e s p o n d i n g p y r a z o l i n e s . The u n s a t u r a t e d e s t e r s c a n a l s o be p r e p a r e d b y this method, h o w e v e r , the y i e l d s of some of t h e m a r e low and another synthet ic method w a s found n e c e s s a r y . We have adapted the m o d i f i e d W i t t i g r e a c t i o n f o r this p u r p o s e . These synthetic methods w i l l be d i s c u s s e d b e l o w . In Tab le I and Table II a r e l i s t e d the 2 - a l k y l -c y c l o p r o p a n e s and c^. jS-u^saturated e s t e r s r e s p e c t i v e l y , p r e p a r e d f o r the p r e s e n t study. P y r a z o l o n e method The use of p y r a z o l i n e s as the s t a r t i n g m a t e r i a l f o r the p r e -p a r a t i o n of 2 - a l k y l c y c l o p r o p a n e s and 0 ( , / 3 - u n s a t u r a t e d e s t e r s w a s b a s e d on the e x p e r i e n c e encountered i n our l a b o r a t o r y w i t h such c o m -pounds. It has been s.hown (37-39) that p y r a z o l i n e s can e a s i l y be p r e -p a r e d b y the addi t ion of a d i a z o a l k a n e to an o l e f i n w h i c h i s a c t i v a t e d b y an e l e c t r o n w i t h d r a w i n g group such as c a r b o m e t h o x y , a c e t y l o r cyano. The addi t ion p r o d u c t i s a A ^ -pyrazolone w h i c h u s u a l l y r e a r r a n g e s to - 14 -T A B L E I 2 - A l k y l c y c l o p r o p a n e s C y c l o p r o p a n e X ' 32 C0 2 M e 3^3, C O z M e 34 C0 2 M e 35 C0 2 M e 18 C0 2 M e 17 C O z M e 36 ' C0 2 M e 2LL C0 2 M e 16 C O z M e 38 C O z M e _39_ C0 2 M e _2_ C O M e J-0. C N 41 C N R 2 R 3 R 4 R 5 R e f e r e n c e M e M e M e H H t h i s w o r k M e H E t H H 7 M e E t H H H 7 H M e M e H H :this w o r k M e H M e H H 3 M e M e H H H 3 Ti H M e M e H 3 H H M e H H 2 H M e H H H 2 M e H M e M e H 6 M e M e H M e H M e H M e H H 5 M e H M e H H this w o r k M e M e H H H th is w o r k T A B L E II ojj, ^ - U n s a t u r a t e d e s t e r s R v XOoMe o( . ^ - U n s a t u r a t e d es ter R 1 R 2 " R 3 m e t h o d * o r r e f e r e n c e 42 M e i - P r H W . 43 M e H i - P r W . and P . 44. H i - P r H W . A£ H H i - P r W . and P . 4.4 M e E t H W . i l M e H E t w. I.S. H E t H p . ( 2 ) 42- H H E t w. W = m o d i f i e d W i t t i g r e a c t i o n , P = p y r a z o l i n e m e t h o d . - 1 5 -R ! R 2 C N 2 + >==< , ^ R~|- I o r H - ( H R = H , a l k y l X = C 0 2 R , C O R , C N 2 3 the m o r e stable f o r m , A -pyrazo lone i f R i s a h y d r o g e n . These p y r a z o l o n e s , when d e c o m p o s e d , g ive a p r o d u c t m i x t u r e c o n s i s t i n g of c y c l o p r o p a n e s and o l e f i n s f o l l o w i n g the l o s s of n i t r o g e n ( 1 - 7 , 4 0 - 4 6 ) R -—rx A A. ~ =s- c y c l o p r o p a n e s + o l e f i n s IN - IN ? A l l of the 2 - a l k y l c y c l o p r o p a n e s l i s t e d i n Tab le I have been , 1 7 p r e p a r e d f r o m t h e i r c o r r e s p o n d i n g A - o r A -pyrazo lone b y e i t h e r t h e r m a l o r p h o t o c h e m i c a l d e c o m p o s i t i o n . A l l of the r e q u i r e d p y r a z o l i n e s have been p r e p a r e d p r e v i o u s l y i n th is l a b o r a t o r y except the fo l lowing , 3 , 5 , 5 - t r i m e t h y l - 3 - c a r b o m e t h o x y — A ^ - p y r a z o l i n e ( 5 0 ) , 5 , 5 - d i m e t h y l -1 2 3 - c a r b o m e t h o x y — A - and A - p y r a z o l i n e ( 5 3 and 5 4 ) and 3 , 5 - d i m e t h y l -3 - c y a n o — A * - p y r a z o l i n e ( 5 5 ) , and t h e i r p r e p a r a t i o n and d e c o m p o s i t i o n are d i s c u s s e d b e l o w . 3 , 5 , 5 - T r i m e t h y l - 3 - c a r b o m e t h o x y — A ^ - P y r a z o l i n e (5 0 ) w a s p r e p a r e d b y the addi t ion of m e t h y l m e t h a c r y l a t e to an e t h e r e a l so lu t ion o f d i a z o - i s o p r o p a n e at - 2 5 w h i c h was p r e p a r e d , i n s i t u , b y o x i d i z i n g - 16 -acetone h y d r a z o n e w i t h s i l v e r oxide (47). The p y r a z o l i n e s t r u c t u r e w a s / 2 5 ° l "\ A 2 ^ C O z M e C O , M e " / " N " 50 r e a d i l y c h a r a c t e r i z e d b y N . M . R . w h i c h shows the e s t e r m e t h y l at 6.27 X and the n o n - e q u i v a l e n t C - 5 methyls at &.60 X and 8.64 X- h y d r o -gens at C - 4 show an A B s y s t e m (48) w i t h a p a i r of doublets at 8.03 X a^d 8.79 X > ^ g e m ~ ^ ' ^ c . p . s . T h i s A ' ' ' - p y r a z o l i n e when d e c o m p o s e d b y heat ing on a s t e a m bath gave a p r o d u c t m i x t u r e c o n s i s t i n g of m e t h y l 1, 2, 2 - t r i m e t h y l c y c l o p r o p a n e - 1 - carboxyla te (32) and m e t h y l t r a n s - 2 , 4 -d i m e t h y l - 2 - p e n t e n o a t e (43) i n the r a t i o of 84:16. The e x c l u s i v e f o r m a -t ion of the t r a n s o l e f i n (43) suggests that o n l y one h y d r o g e n on C - 4 i s i n | ^ C 0 2 M e / ! ' 2 O z M e 50 32 43 a p o s i t i o n to m i g r a t e and b y ana logy w i t h the m e c h a n i s m suggested b y M c G r e e r , et. a l . (6, 7) i t w o u l d be the h y d r o g e n t r a n s to the es ter group as i n the c o n f o r m a t i o n 51 . It i s n o t c l e a r at this t i m e w h y that h y d r o g e n should be i n the p r e f e r r e d p o s i t i o n f o r m i g r a t i o n s ince a m e t h y l group w o u l d be expected to be l a r g e r than a c a r b o m e t h o x y group and thus the - 17 -a l t e r n a t i v e c o n f o r m a t i o n 52 w o u l d be expected to be f a v o r e d . C O o M e YY z 51 52 The s t r u c t u r e of m e t h y l 1, 2, 2 - t r i m e t h y l c y c l o p r o p a n e - 1 - c a r -boxyla te (32) w a s d e t e r m i n e d b y i ts N . M . R . s p e c t r u m w h i c h shows three s ingle ts at 9.01 f j , 8.87 hC and 8.74 ^ for the r i n g m e t h y l s . The two g e m i n a l h y d r o g e n s on C - 3 f o r m an A B s y s t e m (48) and show a p a i r The s t e r e o c h e m i s t r y of m e t h y l t r a n s - 2 , 4 - d i m e t h y l - 2 - p e n t e n o a t e (43) can be d i s t i n g u i s h e d f r o m i t s c i s , i s o m e r (42) p r e p a r e d b y the method of m o d i f i e d W i t t i g r e a c t i o n ( d i s c u s s e d l a t e r ) on the b a s i s of t h e i r N . M . R . s p e c t r a . The C - 3 h y d r o g e n of the c i s i s o m e r appears at h i g h e r f i e l d (0.87 T") than that of t r a n s i s o m e r because the l a t t e r i s d e s h i e l d e d (49) b y the a n i s o t r o p i c c a r b o m e t h o x y group, w h i c h i s c i s to i t . On the other hand, the C - 4 methine h y d r o g e n of the c i s i s o m e r is at l o w e r f i e l d (0.61 ^) than that of the t r a n s i s o m e r as i t i s d e s h i e l d e d b y the c a r b o -methoxy group. 5 , . 5 - D i m e t h y l - 3 - c a r b o m e t h o x y - A - P y r a z o l i n e (53) 'was p r e p a r e d of doublet at 9.74 X and 8.58 \ w i t h J g e m C^.4.6 c . p . s . b y r e a c t i n g m e t h y l a c r y l a t e w i t h d i a z o - i s o p r o p a n e , i n s i t u , at -25 . T h i s A h - p y r a z o l i n e i s capable of r e a r r a n g i n g to the m o r e stable conjugated - l i / C ° 2 M e 2 5 o J j { ( C H 3 ) 2 C N 2 + - = / ^ ^ ^ 53_ 5_4 A - p y r a z o l i n e (54) as s tated e a r l i e r and it w a s found that r e a r r a n g e m e n t o c c u r r e d p a r t i a l l y b e f o r e the p r o d u c t was i s o l a t e d f r o m the r e a c t i o n m i x t u r e . A t t e m p t e d s e p a r a t i o n of these i s o m e r s b y d i s t i l l a t i o n gave a l o w e r b o i l i n g f r a c t i o n c o n s i s t i n g of both i s o m e r s and a h i g h e r b o i l i n g f r a c t i o n of pure A - p y r a z o l i n e (54) as i n d i c a t e d b y N . M . R . a n a l y s e s . The N . M . R . s p e c t r a of the two i s o m e r s are quite d i f f e r e n t because the Lt- i s o m e r i s s y m m e t r i c w i t h r e s p e c t to the plane of the r i n g w h i l e the £\ i s o m e r i s not . The p r e f e r r e d c o n f o r m a t i o n of the A * i s o m e r i s an envelope w i t h the c a r b o m e t h o x y g r o u p at C - 3 i n a pseudo e q u a t o r i a l p o s i t i o n (6). A s a r e s u l t the m e t h y l s on C - 5 and the h y d r o g e n s on C - 4 are n o n - e q u i v a l e n t , the f o r m e r appear at 8.15 X and 8.33 X and the l a t t e r at 6.71 X and 7.49 X- On the other hand, the C - 5 m e t h y l s as w e l l as the C - 4 hydrogens on the A i s o m e r are equiva lent due to s y m m e t r y and as a r e s u l t , the m e t h y l s show a s ingle t at 8.72 X and the hydrogens show a s ing le t at 7.36 X- F u r t h e r m o r e , the A i s o m e r has a h y d r o g e n attached to the N - l w h i c h appears at 3.16 X- -A. m i x t u r e c o n s i s t i n g of both A and A i s o m e r s (53 and 54) was p y r o l y z e d at 1 0 0 - 1 7 0 ° and gave a p r o d u c t mixture of m e t h y l 2, 2 - d i m e t h y l c y c l o p r o p a n e -1 - c a r b o x y -- 19 -0 2 M e C O z M e •1ST 53 C 0 2 M e ^4 C 0 2 M e /NNT H N 35 0 2 M e 54 45 la te (35), m e t h y l c i s - and t r a n s - 4 - m e t h y l - 2 - p e n t e n o a t e (44 and 45) i n a ra t io of 26:4:70. The s t r u c t u r e of m e t h y l 2, 2 - d i m e t h y l c y c l o p r o p a n e - 1 - c a r b o x y -late (35) is i n d i c a t e d p a r t l y b y i ts N . M . R . s p e c t r u m and p a r t l y due to the fact that i t i s the o n l y l o g i c a l c y c l o p r o p a n e p r o d u c t d e r i v e d f r o m the pyrazolone . Its N . M . R . s p e c t r u m shows two s ingle ts at 8.81 ^ and 8.86 X f o r the m e t h y l s on C - 2 . The three hydrogens on C - l and C - 2 f o r m an A B X s y s t e m (48) and show three p a i r s of doublets at 8.50 'X (bh^), 9.0 X ( H A , r e s o l v e d at 100 M c i n benzene) and 9.21 X ( H g ) . The H A „ JTi. <c X H B H - C O z M e X 35 p r o t o n - p r o t o n coupl ing constants are J g e m ' ~ ^ 4 - 0 c - P - s - » J c i s — 8 - 1 C - P - S -and T ^ 5 1 c . p . s . These values are i n good a g r e e m e n t w i t h that t r a n s r _ 20 -of 2, 2 - d i m e t h y l c y c l o p r o pane -1 - c a r b o x y l i c a c i d (the a c i d f o r m of 35) as d e t e r m i n e d b y P a t e l , et. a l . (24). Th<s s t & r e o c h e m i e t r y of m e t h y l cis - and t rans -4-methyl-2 -pentenoate (44 and 45) are a s s i g n e d on the b a s i s of N . M . R . and I. R . a n a l y s e s . The t rans i s o m e r shows an I. R . band at 990 c m " ^ t y p i c a l of • t rans v i c i n a l v i n y l i c hydrogens w h e r e a s the c i s i s o m e r shows a v i n y l C - H i n - p l a n e bending band at 1417 c m " ^ (29). The c i s i s o m e r shows a s m a l l e r p r o t o n - p r o t o n c o u p l i n g constant f o r the v i n y l protons a c r o s s the double bond than the t r a n s i s o m e r (31, 32), e . g . , 11.4 c . p . s . f o r the c i s i s o m e r and 15.8 c . p . s . f o r the t rans i s o m e r . N u c l e a r magnet i c resonance a n a l y s e s a l so show that the C - 3 h y d r o g e n of the t r a n s i s o m e r is at l o w e r f i e l d (3.14 •*() than that of the c i s i s o m e r (4.03 q^) due to d e s b i e l d i n g b y the a n i s o t r o p y of the es ter group (49). 3, 5 - D i m e t h y l - 3 - c y a n o - A ' ' " - p y r a z o l o n e (55) w a s p r e p a r e d b y the a d d i t i o n of m e t b a c r y l o n i t r i l e to diazoethane i n ether at 0°. The N . M . R . s p e c t r u m ( F i g u r e 1) of the product shows i t has .the same g e n e r a l f e a -tures as that of the analogous 3, 5 - d i m e t h y l - 3 - c a r b o m e t h o x y - A - p y r a z o -lone (56) (3) and that i t i s a m i x t u r e of cis_ and t rans i s o m e r s ( C - 3 and - 22 -C - 5 m e t h y l s ) i n the ra t io of 6:7 as e s t i m a t e d b y the i n t e g r a l s of the C - 3 m e t h y l at 8.21 hC and 8.51 *X. r e s p e c t i v e l y . No at tempt w a s made to separate these two i s o m e r s and the m i x t u r e w a s d e c o m p o s e d at 100° to give cis-c...! and t r a n s - 1 , 2 - d i m e t h y l - 1 - c y a n o c y c l o p r o p a n e (41 and 40) and 2 - m e t h y l - 2 - p e n t e n o n i t r i l e (5 7) i n the ra t io of 44:5 3:3. | C N N C N / ^ < ; N - N 2 4i_ (43%) 40_ (5 3%) 55_ E t C H = C ( M e ) C N 5_7 (3%) The p r e s e n c e of a c y c l o p r o p a n e r i n g i n both c i s - and t rans -1, 2 - d i m e t h y l - 1 - c y a n o c y c l o p r o p a n e (41 and 40) i s i n d i c a t e d by t h e i r N . M . R . s p e c t r a w h i c h show no a b s o r p t i o n s below 8.0 'X'. The g e o m e -t r i c a l a s s i g n m e n t to 41 and 40 w e r e made b y c o m p a r i s o n of t h e i r N . M . R . s p e c t r a w i t h those of the analogous c i s and t rans i s o m e r s of m e t h y l 1, 2 - d i m e t h y l c y c l o p r o p a n e - 1 - c a r b o x y l a t e (17 and 18) (3). M o d i f i e d W i t t i g r e a c t i o n A new method has been developed d u r i n g the past 15 y e a r s for the syntheses of o le f ins w h i c h i n v o l v e s a c o n d e n s a t i o n - e l i m i n a t i o n between a phosphonium y l i d (5 8) and an aldehyde o r ketone to f o r m an o l e f i n and a phosphine o x i d e . T h i s r e a c t i o n has been n a m e d the W i t t i g - 23 -R^P = CB!2 + R ^ C O 3=- R l C = C R - + R 3 P O 58 r e a c t i o n (50-62) a f ter P r o f e s s o r G . W i t t i g f o r h i s o b s e r v a t i o n that methylene t r i p h e n y l phosphorane reactecbwith benzophenone to give d i -pbenyl ethylene (59) and t r i p h e n y l phospbine ox ide , and b i s subsequent c o n t r i b u t i o n s to this o l e f i n synthes is (51;52). R e c e n t l y , a m o d i f i e d ether (fr^P^CR^ + 0 2 G O — = » 0 2 C = C H 2 + 0 3 P O 59 W i t t i g r e a c t i o n has been deve loped i n w h i c h a c a r b o n y l c o m p o u n d i s r e -ac ted w i t h a phosphinoxy c a r b a n i o n (60, Z = R) (63-65) o r a pbospbonate c a r b a n i o n (61, Z = O R ) (40) i n s t e a d of a pbospboriium yl id to a f f o r d an o l e f i n . 9 z i - C R o + R ; C O R ? C = C R ' + Z ?P-6 _60 (Z = R) 6l_ ( Z = O R ) The r e a c t i o n of phosphorous y l i d s w i t h c a r b o n y l compounds can give r i s e to c i s and t r a n s o l e f i n s and u s u a l l y the t rans o l e f i n s p r e -dominate . The f i r s t o b s e r v a t i o n of th is p o s s i b i l i t y w a s the f o r m a t i o n of s t i l b e n e s . f r o m the r e a c t i o n of b e n z y l i d e n e t r i p h e n y l phosphorane (62) and benzaldehyde w h i c h gave a c i s : t r a n s ra t io of 3:7 (51). O c c a s i o n a l l y , 0-P = C H 0 + 0 C H O 3 \ 0 62 - 24 -the c i s i s o m e r s p r e d o m i n a t e (67-69), e . g . , the r e a c t i o n of t r i e t h y l 0{-phosphonopropionate c a r b a n i o n (63) and e thy Lb u tyr aldehyde gave ra t io of 75:25 (69). In g e n e r a l , the o l e f i n f o r m a t i o n b y the W i t t i g r e a c t i o n o r i ts m o d i f i e d r e a c t i o n i s i n t r i n s i c a l l y a s t e r e o - n o n s e l e c t i v e r e a c t i o n . T h e r e a r e v a r i o u s f a c t o r s such as the s t r u c t u r e of the r e a c t a n t s , the effects of the sa l ts present, . , na ture of so lvent , t e m p e r a t u r e of r e a c t i o n and the s o l u b i l i t y of the y l i d and r e a c t i o n i n t e r m e d i a t e , w h i c h c o u l d affect the s t e r i c c o u r s e of the r e a c t i o n and thus the ra t io of c i s and t r a n s o l e f i n s . These f a c t o r s w i l l not be d i s c u s s e d h e r e s ince they have been r e v i e w e d r e c e n t l y (60-62,70) ' and they are out of the scope of this t h e s i s . R e c e n t l y K i n s t l e (69) p r e p a r e d a s e r i e s of o(,^-unsaturated e s t e r s by the r e a c t i o n of a ldehydes w i t h phosphonate c a r b a n i o n s and the r e s u l t s showed p r e d o m i n a n t l y the c i s i s o m e r s . T h i s l e d us to a p p l y this m o d i f i e d W i t t i g r e a c t i o n to synthes ize a s e r i e s of m e t h y l 2 - p e n t -enoates ( l i s ted i n Table II, p. 14) that are r e q u i r e d for the present r e s e a r c h . The r e s u l t s (Table III) d i f fe r f r o m that of K i n s t l e (69) i n two aspects , f i r s t l y , the o le f ins obtained under s i m i l a r r e a c t i o n c o n -et t h y l c i s - and t r a n s - 2 - m e t h y l - 4 - e t h y l - 2 - h e x e n o a t e (64 and 65) i n the H - 25 -T A B L E III P r o d u c t c o m p o s i t i o n s for the m o d i f i e d W i t t i g r e a c t i o n O ( R O ) 2 P C R ' C 0 2 M e + R ' C H O R''cH = CR^CO- jMe 66 R' RU R ^-unsaturated e s t e r s c i s t rans C H 3 i - C 3 H y C 2 H 5 72 28 C H 3 i - C 3 H ? C H 3 70 3 0 * H i - G 3 H C 2 H 5 . 4 96 H i - C 3 H ? C H 3 31 69 C H 3 C 2 H 5 C 2 H 5 13 87 C H 3 C 2 H 5 C H 3 38 62 H C 2 H 5 C 2 H 5 4 96 * K i n s t l e 's r e s u l t , see ref . 69. d i t ions to those u s e d b y K i n s t l e w e r e p r e d o m i n a n t l y t rans i s o m e r s except f o r 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 i n w h i c h case the c i s i s o m e r (42) p r e d o m i n a n t e d . Secondly , when d i m e t h y l phosphonate (66, R = M e ) w a s used i n s t e a d of diethylphosphonate anion (66, R = E t ) , the y i e l d of c i s o l e f i n s i n c r e a s e d g r e a t l y . F o r e x a m p l e , the y i e l d of m e t h y l c i s - 4 - m e t h y l - 2 -pentenoate (44) i n c r e a s e d f r o m 4% to 31%. F u r t h e r study of this r e a c t i o n m i g h t f i n d an i n t e r e s t i n g r e l a t i o n between the s t r u c t u r e of the phosphonate and the s t e r e o c h e m i s t r y of the product . - 26 -II-2 T H E R M A L R E A R R A N G E M E N T O F C Y C L O P R O P A N E S T h e r m a l r e a r r a n g e m e n t of c y c l o p r o p a n e s and i d e n t i f i c a t i o n of products A s e r i e s of c y c l o p r o p a n e s w i t h a C - l c a r b o m e t h o x y , a c e t y l o r cyano g r o u p and a C - 2 a l k y l g r o u p bad been p r e p a r e d as d e s c r i b e d e a r l i e r and are l i s t e d i n Tab le I (p. 14). Some of these are g e o m e t r i c a l i s o m e r s having the C - 2 a l k y l g r o u p and the C - l func t iona l g r o u p i n e i t h e r the c i s o r t rans r e l a t i o n s h i p . A l l of these c y c l o p r o p a n e s w e r e sub jec ted to t h e r m a l r e a r r a n g e m e n t r e a c t i o n condi t ions at t e m p e r a t u r e s r a n g i n g f r o m 240° to 300°. A ha l f g r a m s a m p l e of the c y c l o p r o p a n e s i n a s t a n d a r d N . M . R . s a m p l e tube w a s s e a l e d at a p r e s s u r e of 1 m m . H g . o r l e s s and heated i n a tube furnace at the d e s i r e d t e m p e r a t u r e . The t h e r m a l r e -a r r a n g e m e n t r e a c t i o n s w e r e f o l l o w e d b y N . M . R . a n a l y s e s to o b s e r v e any changes as they o c c u r r e d . The p r o d u c t m i x t u r e w a s then a n a l y s e d b y v a p o r phase c h r o m a t o g r a p h y and the components s e p a r a t e d and i d e n t i f i e d as d i s c u s s e d l a t e r . Two facts w e r e o b s e r v e d f r o m the t h e r m a l r e a r r a n g e m e n t r e -act ions of the c y c l o p r o p a n e s , The f i r s t i s that c y c l o p r o p a n e s w i t h a C - 2 a l k y l g r o u p c i s to the C - l c a r b o n y l group r e a r r a n g e d to ^ ^ - u n s a t u r a t e d e s t e r s or ketones e x c l u s i v e l y w h e r e a s the i r c o r r e s p o n d i n g t rans i s o m e r s r e m a i n e d unchanged under i d e n t i c a l r e a c t i o n c o n d i t i o n s . The second i s that i f the C - l c a r b o n y l g r o u p i n the c y c l o p r o p a n e s w a s r e p l a c e d b y a cyano group, no change w a s o b s e r v e d to the m o l e c u l e even w h e r e i t w a s c i s to the C - 2 a l k y l group . - 27 -The ~i, 6-unsaturated e s t e r s and ketone obta ined f r o m the t h e r m a l r e a r r a n g e m e n t of c y c l o p r o p a n e s ( F i g u r e 2) have been i d e n t i -f i e d and t h e i r p h y s i c a l data d e t e r m i n e d . The i d e n t i f i c a t i o n s a r e b a s e d on e l e m e n t a l m i c r o - a n a l y s e s and s p e c t r o s c o p i c ana lyses ( N . M . R , and I. R . ). The l a t t e r w i l l be d i s c u s s e d as f o l l o w s . T h e r m a l r e a r r a n g e m e n t of m e t h y l 1, 2, 2 - t r i m e t h y l c y c l o p r o p a n e -1 - carboxy la te (32) at 2 8 0 ° f o r 10 hours y i e l d e d m e t h y l 2, 4 - d i m e t h y l - 4 -pentenoate (67) w i t h l e s s than 2% 32 r e m a i n i n g . The N . M . R . s p e c t r u m of 67 shows two s i n g l e t s at 8.31 -f and 6.41 'X due to the m e t h y l on C - 4 and the e s t e r m e t h y l r e s p e c t i v e l y . The C - 2 m e t h y l showed a doublet at 8.91 X (J —6.5 c .p . s . ) s ince i t w a s s p l i t b y the h y d r o g e n on C - 2 w h i c h a p p e a r e d , together w i t h the C - 2 methylene h y d r o g e n s , as a set of m u l t i -plet jat the r e g i o n 7.20 'X to 8.10 X- The t e r m i n a l methylene h y d r o g e n s showed a b r o a d s ing le t at 5.31 X-Two - u n s a t u r a t e d e s t e r s together w i t h t r a c e amount of m e t h y l t rans - 1 - m e t h y l - 2 - e t h y l c y c l o p r o p a n e - 1 - c a r b o x y l a t e (33) (methyl and e thy l groups t rans) w e r e obta ined w h e n 33 w a s heated at 2 8 0 ° for 18 h o u r s . T h e y are m e t h y l c i s - and t r a n s - 2 - m e t h y l - 4 - h e x e n o a t e (68 and 69). V a p o r phase c h r o m a t o g r a p h i c a n a l y s i s shows that 68 and 69 w e r e f o r m e d i n the ra t io of 1:4.7. T h e i r N . M . R . s p e c t r a (60 M c and 100 M c ) show the s k e l e t a l s t r u c t u r e of m e t h y l 2 - m e t h y l - 4 - h e x e n o a t e but cannot d e t e r -mine t h e i r c i s - t r a n s g e o m e t r y due to the s i m i l a r i t y and c o m p l e x i t y of the m u l t i p l e t s for the v i n y l hydrogens (Table IV) . H o w e v e r , the g e o m e t r y F I G U R E -2 — P r o d u c t s of the t h e r m a l r e a r r a n g e m e n t of c i s -2 - a l k y l c y c l o p r o p a n e s - 29 -T A B L E IV N . M . R . data of m e t h y l c i s - and t rans -2 - m e t h y l - 4 - h e x e n o a t e (68 and 69) CIS >8) t rans (69) e s te r m e t h y l C -2 m e t h y l v i n y l m e t h y l C -2 and C - 3 h y d r o g e n s v i n y l h y d r o g e n s 6.40 "T, s ingle t 8.88 doublet J i i i 6.3 c . p . s . 8.39 T , doublet J 5.7 c . p . s . 7.35 - 8.05 < m u l t i p l e t 4.25 - 4.95 "T m u l t i p l e t 6.41 T , s i n g l e t 8.96 T , doublet J ^£6 .5 c . p . s . 8.36 X, doublet 4.7 c.p.s..' 7.50 - 8.10 X m u l t i p l e t 4.50 - 5.00 t m u l t i p l e t of 68 and 69 c a n be d i s t i n g u i s h e d b y I. R . ana lyses on the b a s i s that the t rans i s o m e r (69) showed a C - H o u t - o f - plane bending band at 973 c m " ^ (29). F u r t h e r m o r e , a c o n s i d e r a t i o n of the s t e r e o c h e m i s t r y of the t h e r m a l r e a r r a n g e m e n t r e a c t i o n indica tes that the t rans i s o m e r w o u l d be f o r m e d p r e d o m i n a n t l y (this w i l l be d i s c u s s e d l a t e r ) . M e t h y l 2, 2 - d i m e t h y l c y c l o p r o p a n e - 1 - c a r b o x y l a t e (35) r e a r r a n g e d on heat ing at 2 5 8 ° f o r 50 h o u r s (95% completed) to m e t h y l 4 - m e t h y l - 4 -pentenoate (70) w h i c h w a s r e a d i l y i d e n t i f i e d b y i ts N . M . R . s p e c t r u m . It shows four peaks , a l l s i n g l e t s , at 8.25 X, 7.64 X, 6.35 X and 5.26 X w i t h i n t e g r a l s c o r r e s p o n d i n g to 3, 4, 3 and 2 hydrogens r e s p e c t i v e l y . The peaks at 8.25 X and 6.35 X a re due to the v i n y l m e t h y l and e s t e r m e t h y l r e s p e c t i v e l y . The low f i e l d s ingle t at 5.26 X 1 S due t o the t e r m i -n a l methylene h y d r o g e n s . The C - 2 and C - 3 methylene h y d r o g e n s showed - 30 -a s ing le t at 7.64 X w h i c h ind ica tes that these hydrogens are equiva lent . M e t h y l Z - m e t h y l - 4 - p e n t e n o a t e (31) w a s obta ined i n 99% y i e l d when m e t h y l t r a n s - 1 , 2 - d i m e t h y l c y c l q p r o p a n e -1 - c a r b o x y l a t e (18) w a s heated at 300° for 18 h o u r s . Its N . M . R . s p e c t r u m shows a s i n g l e t at 6.49 *T due to the es ter m e t h y l . The C - 2 m e t h y l showed a doublet at 8.97 X (J £H 6.5 c . p . s . ) as i t w a s s p l i t b y the C - 2 methine h y d r o g e n w h i c h a p p e a r e d w i t h the C - 3 methylene hydrogens as a set of m u l t i p l e t s i n the r e g i o n of 7.35 X to 8.10 X. The t e r m i n a l methylene h y d r o g e n s showed two sets of m u l t i p l e t s c e n t r e d at 5.05 X and 5.26 X w h e r e a s the C - 4 v i n y l h y d r o g e n showed another m u l t i p l e t at 4.15 X to 4.85 X-M e t h y l t r a n s - 2 , 3 - d i m e t h y l c y c l o p r o p a n e - 1 - c a r b o x y l a t e (36) r e a r r a n g e d t h e r m a l l y to m e t h y l 3 - m e t h y l - 4 - p e n t e n o a t e (71) . A f t e r heat ing 36' at 2 5 8 ° f o r 50 h o u r s , the r e a c t i o n m i x t u r e conta ined 10% of unchanged 36 and 90% of 71. The N . M . R . s p e c t r u m of 71 shows a s i n g l e t at 6.41 X due to the e s t e r m e t h y l , a doublet at 8.79 X ( J ^ -6 .3 c . p . s . ) due to the C - 3 m e t h y l w h i c h was s p l i t b y the C - 3 methine h y d r o -gen at 7.35 X ( complex m u l t i p l e t ) . The two n o n - e q u i v a l e n t C - 2 m e t h y l -ene hydrogens w e r e both s p l i t by the C - 3 methine h y d r o g e n into d o u -b le t s at 7.79 T (J ^ 8.6 c . p . s . ) and 7.76 -f ( J ^ 5 . 8 c . p . s . ), the l o w e r f i e l d l i n e of: each doublet c o i n c i d e and thus a total of three l i n e s r e s u l t -ed. T h e r e w e r e a l so three sets of m u l t i p l e t s c e n t r e d at 5.18 X> 4.95 X and 4.22 X due to the two t e r m i n a l methylene hydrogens and the C - 4 v i n y l hydrogen r e s p e c t i v e l y . - 31 -M e t h y l 4-pentenoate (72) was obta ined f r o m the t h e r m a l r e -a r r a n g e m e n t of m e t h y l c i s - 2 - m e t h y l c y c l o p r o p a n e - 1 - c a r b o x y l a t e (37) . Its N . M . R . s p e c t r u m shows three s ingle ts at 7.67 ''(, 7.62 X a n d 6.45 X a t t r ibuted to the C - 2 methylene h y d r o g e n s , the C - 3 methylene hydrogens and the e s t e r m e t h y l . The two t e r m i n a l hydrogens showed two sets of m u l t i p l e t s at 5.08 X and 4.84 X w h e r e a s the v i n y l h y d r o g e n at C - 4 showed a m u l t i p l e t at 4.09 "T. M e t h y l c is , ' , t rans - 1, 2, 3 - t r i m e t h y l c y c l o p r o p a n e - 1 - c a r b o x y l a t e (38) r e a r r a n g e d t h e r m a l l y to m e t h y l 2, 3 - d i m e t h y l - 4 - p e n t e n o a t e (73). . The r e a c t i o n m i x t u r e conta ined 95% of 73 and 5% of 38 a f ter 12 h o u r s at 280° . Its N . M . R . s p e c t r u m shows a s ingle t at 6.38 X due to the e s t e r m e t h y l . The C - 2 and C - 3 methine hydrogens showed a m u l t i p l e t c e n t r e d at 7.64 X- The C - 2 m e t h y l w h i c h w a s s p l i t b y the C - 2 h y d r o g e n showed a doublet at 9.01 X (J ^ 6.6 c . p . s . ) and the C - 3 m e t h y l w h i c h w a s s p l i t b y the C -3 h y d r o g e n a lso showed a doublet at 8. 94 X (J — 6.7 c . p . s . ). 5.14 T , T h r e e sets of m u l t i p l e t s at j 4.92 X a n d 4.31 X w e r e a s s i g n e d to the two t e r m i n a l hydrogens and the C - 4 v i n y l hydrogens r e s p e c t i v e l y . 3 - M e t h y l - 5 - h e x e n - 2 - o n e (74) w a s obta ined f r o m the t h e r m a l r e a r r a n g e m e n t of t rans - 1, 2 - d i m e t b y l - 1 - a c e t y l c y c l o p r o p a n e (2) . The s t r u c t u r e of 74 bad been r e p o r t e d e a r l i e r (5). - 32 -K i n e t i c s tudies The rates of t h e r m a l r e a r r a n g e m e n t of the c y c l o p r o p a n e s to t h e i r c o r r e s p o n d i n g ^ . ^ - u n s a t u r a t e d compounds havei been s t u d i e d . The g e n e r a l method of rate d e t e r m i n a t i o n w a s to p r e p a r e a n u m b e r of s a m p l e s sea led i n 4 m m x l 2 0 m m tubes . These w e r e p l a c e d i n the f u r n a c e and came to t h e r m a l e q u i l i b r i u m i n l e s s than 15 m i n u t e s . The t e m p e r a t u r e of the f u r n a c e w a s m a i n t a i n e d to ± 0 . 5 ° C . S a m p l e s w e r e r e m o v e d at v a r y i n g i n t e r v a l s c o o l e d and a n a l y s e d b y V . P . C . f o r the - u n s a t u r a t e d product i n r e l a t i o n to the u n r e a c t e d c y c l o p r o p a n e c o m p o u n d . Th-flfC w a s no evidence f o r p o l y 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 of the reac tants o r products and thus the m o l e f r a c t i o n as d e t e r m i n e d b y i n t e g r a t i o n of the peak areas c o u l d be used i n the rate equat ion. The a c c u r a c y of these m e a s u r e m e n t s depends on the a c c u r a c y of the i n t e g r a t i o n (disc i n t e g r a t i o n w a s used) and the r e l a t i v e r e s p o n s e b y the detector to the i s o m e r i c s a m p l e s . These r e s u l t s gave e x c e l l e n t f i r s t o r d e r k i n e t i c s w i t h no i n d u c t i o n p e r i o d . The rate e x p r e s s i o n u s e d w a s the f o l l o w i n g , 2.303 a n k = l o g _ 9 _ t. a Q - x w h e r e a Q i s the i n i t i a l m o l e f r a c t i o n of the s t a r t i n g c y c l o p r o p a n e , and x i s the m o l e f r a c t i o n of the i,ci-unsaturated compound f o r m e d i n t i m e i n t e r v a l t. A plot of the quant i ty log ( a 0 / a Q - x ) v e r s u s t w i l l r e s u l t i n a s t r a i g h t l i n e for a f i r s t - o r d e r r e a c t i o n . The slope m of the l i n e obtained m u l t i p l i e d b y 2.303 w i l l be equal to the rate constant k, - 33 -k = 2.303 X m The h a l f - l i f e of the r e a c t i o n was c a l c u l a t e d b y the f o l l o w i n g equation (71), 2.303 l o g 2 l o g 2 h/z k The r e s u l t s of the k i n e t i c s tudies are tabulated i n Table V , and some t y p i c a l f i r s t - o r d e r rate plots are shown i n F i g u r e s 3, 4 and 5. The heats of a c t i v a t i o n A H and the e n t r o p i e s of a c t i v a t i o n AS"*" w e r e c a l c u l a t e d b y the f o l l o w i n g f o r m u l a (72), k B T - A H * / R T A S * / R k = e e h w h e r e k_, i s the B o l t z m a n n constant , and h is P l a n c k ' s constant . The B l o g a r i t h m f o r m of this equat ion i s k 1 / A H " | A S * l o g = 10.319 j j 4-T T \ 4.574 / ' 4.574 and a plot of l o g ( k / T ) v s . 1/T gave a s t ra ight l i n e whose slope m u l -t i p l i e d b y 4.574 gave A H . Subst i tut ing this A H b a c k to the above equation gave A S * . Some of these plots (log k / T v s . 1/T) are shown i n F i g u r e s 6, 7 and 8. A w o r d should be s a i d c o n c e r n i n g the a c c u r a c y of the rate constants obta ined. The e r r o r s of m e a s u r e m e n t of t i m e , the m o l e f r a c t i o n of the s t a r t i n g c y c l o p r o p a n e and of the Y , & - u n s a t u r a t e d o l e f i n - 34 -T A B L E V i l r e a r r a n g e m e n t of c y c l o p r o p a n e s - 25.4 22.0 25.2 _ 36.7 * F o r the f o r m a t i o n of the t r a n s o l e f i n (69) , the r a t e constant and the h a l f - l i f e w e r e 1.26 and 15.31 r e s p e c t i v e l y . ' i The e s t i m a t e d - m a x i m u m e r r o r s i n A H . a n d A S are ± 1 0 % . - 36 -t (hr) F I G U R E 4 - F i r s t - o r d e r rate plots f o r the t h e r m a l r e a r r a n g e m e n t of 18, 33 and 35 - 37 -0.6 L t (hr) F I G U R E 5 - F i r s t - o r d e r rate plots f o r the t h e r m a l r e a r r a n g e m e n t of 36, 37 :and- 38 - 40 -F I G U R E 8 - A c t i v a t i o n plots f o r the t h e r m a l r e a r r a n g e m e n t , o £ 36,.- 37 and 38 - 41 -a r e v e r y s m a l l ( <^  1%). The b iggest e r r o r i s the t e m p e r a t u r e of the r e -a c t i o n . The t e m p e r a t u r e of the r e a c t i o n furnace w a s kept to w i t h i n ± 0 . 5 ° o r be t te r . F r o m the A r r h e n i u s equat ion this t e m p e r a t u r e v a r i a t i o n c o r -responds to an e r r o r of a p p r o x i m a t e l y ±5 % i n the rate constant (100). D i s c u s s i o n of r e s u l t s The r e s u l t s of the t h e r m a l r e a r r a n g e m e n t r e a c t i o n s on the s e r i e s of 2 - a l k y l - 1 - c y a n o - , 1 - a c e t y l - and 1 - c a r b o m e t h o x y c y c l o p r o p a n e s show two s i g n i f i c a n t fac t s . F i r s t l y , a l l c i s - 2 - a l k y l - 1 - a c e t y l and 1 - c a r b o m e t h -o x y c y c l o p r o p a n e s r e a r r a n g e d e x c l u s i v e l y to t h e i r c o r r e s p o n d i n g 6-unsatura ted ketones and e s t e r s ( F i g u r e 2) i n quant i tat ive y i e l d , w h e r e a s t h e i r t r a n s i s o m e r s r e m a i n e d unchanged under i d e n t i c a l r e a c t i o n c o n -d i t i o n s . F o r e x a m p l e , m e t h y l c i s - 2 - m e t h y l - 1 - c y c l o p r o p a n e c a r b o x y l a t e (37) y i e l d e d m e t h y l 4-pentenoate (72) w h e n heated at 2 7 0 ° w h i l e the t r a n s i s o m e r (16) showed no s i g n of change. Secondly , w h e n the C - l ^0* ^ C 0 2 M e 72 37 no change 16 - 42 -c a r b o n y l g r o u p i n . the c y c l o p r o p a n e m o l e c u l e w a s r e p l a c e d by a cyano g r o u p , no o b s e r v a b l e change o c c u r r e d even if i t was c i s to the C - 2 a l k y l g r o u p . Thus both c i s - and t rans - 1, 2 - d i m e t h y l - 1 - c y a n o c y c l o p r o -pane (41 and 40) r e m a i n e d unchanged after be ing heated at 2 6 0 ° for 17 h o u r s . o r - ' ' ^ ~ C N 2 6 0 ° no change 40 41 The m e c h a n i s m for the t h e r m a l r e a r r a n g e m e n t of c i s - 2 - a l k y l -1 - a c e t y l and 1 - c a r b o m e t h o x y c y c l o p r o p a n e s to the - u n s a t u r a t e d ketones and e s t e r s had been p r o p o s e d b y M c G r e e r , et a l . (34) to i n v o l v e an a l l y i c enol i n t e r m e d i a t e 76. The r e s u l t s of the p r e s e n t s tudies of the H R . 75 C R 2 / O H 76 o l e f i n R = H , a l k y l X = R , O R t h e r m a l r e a r r a n g e m e n t . react ions suggest that this i n t e r m e d i a t e a r i s e s v i a a s i x - m e m b e r e d c y c l i c t r a n s i t i o n state 77 by an i n t r a m o l e c u l a r 1, 5 - h y d r o g e n t r a n s f e r of a h y d r o g e n f r o m the C - 2 a l k y l to the oxygen i n the C - l c a r b o n y l c o n c e r t e d w i t h opening of the c y c l o p r o p a n e r i n g at - 43 -C - l and C - 2 . T h i s i s p o s s i b l e o n l y if the C - 2 a l k y l and the C - l c a r b o n y l 75 ^ G R 2 i i 77 x~—- \ x^ 76 are c i s to each o ther ; w h e r e a s i t would not be p o s s i b l e w i t h the two groups i n t r a n s g e o m e t r y . The c y c l i c t r a n s i t i o n state i s a l s o suggested b y the fact that the n i t r i l e s do not r e a c t . The C — C S . N group i s l i n e a r and not able to b r i n g the n u c l e o p b i l i c n i t r o g e n into c l o s e p r o x i m i t y to the h y d r o g e n of the C - 2 m e t h y l . D u r i n g the c o u r s e of this r e s e a r c h , R o b e r t s , et a l . (73-75) have r e p o r t e d a f o u r - s t e p r e v e r s i b l e t h e r m a l i s o m e r i z a t i o n of one h o m o a l l y l i c c a r b o n y l compound 79 to another 83 v i a the a l l y l i c enols 80 and 82 and the c y c l o p r o p y l c a r b o n y l compound 81. T h e y a l s o demon-s t r a t e d the whole r e v e r s i b l e sequence, 79 83, by d e u t e r i u m t r a c e r e x p e r i m e n t s and thus showed that r e v e r s i b l e i n t r a m o l e c u l a r h y d r o g e n t r a n s f e r s are t h e r m a l l y induced between a l iphat i c a l l y l i c enols and the - 44 -A = H , R , A r , O R '83 82_ B = H , R , A R , C O R , C O A r , C O z R c y c l o p r o p y l c a r b o n y l s y s t e m . T h e r e a r e s e v e r a l other r e a c t i o n s that p r o b a b l y o c c u r v i a s i m i l a r i n t r a m o l e c u l a r 1, 5 - h y d r o g e n shi f ts that have been r e p o r t e d i n the recent l i t e r a t u r e . The t h e r m a l r e a r r a n g e m e n t of 2, 2 - d i m e t h y l c y c l o pro pane aldehyde (84) to 4 - m e t h y l - 4 - p e n t e n a l (86) has been r e p o r t e d b y Ohlof f (77) to o c c u r v i a t r a n s i t i o n state 85, F a n t a and 84 85_ 86_ c o - w o r k e r s r e p o r t e d the t r a n s i t i o n state 88 for the t h e r m a l i s o m e r i z a -t ion of a c y l a z i r i d i n e s (87) to give unsaturated a m i d e s (89_) A n o t h e r c l o s e l y r e l a t e d r e a c t i d n is the t h e r m a l r e a r r a n g e m e n t of c i s - 1 - m e t h y l -- 45 -R R 87 88 89 2 - v i n y l c y c l o pro pane (90) to c i s - 1, 4 -hexadiene (91) f o r which an i n t r a -m o l e c u l a r 1, 5 - h y d r o g e n t r a n s f e r has also been p r o p o s e d (80). T h i s d i f f e r s f r o m the o thers i n that 'a c a r b o n - c a r b o n double bond i s i n v o l v e d 21 11 i n the h y d r o g e n t r a n s f e r i n s t e a d of a c a r b o n - o x y g e n double bond. The p r o p o s e d t r a n s i t i o n states for these r e a c t i o n s a r e s i m i l a r to the s i x -m e m b e r e d c y c l i c t r a n s i t i o n state 77 suggested e a r l i e r for the t h e r m a l r e a r r a n g e m e n t of c y c l o p r o p a n e s . i i X 77 - 46 -A c y c l i c t r a n s i t i o n state, such as 77, w o u l d have s i g n i f i c a n t l y l e s s f r e e d o m of m o t i o n than the i n i t i a l state. A r e a c t i o n w h i c h i n v o l v e s such a c y c l i c t r a n s i t i o n state w o u l d be expected to show a v e r y l a r g e negat ive entropy- of a c t i v a t i o n (76). T h i s i s indeed the case f o r o u r k i n e t i c s tudies of the t h e r m a l r e a r r a n g e m e n t r e a c t i o n s of c i s - 2 - a l k y l -c y c l o p r o p a n e - 1 - c a r b o x y l a t e s (Table V ) gave v e r y l a r g e negat ive e n t r o p i e s of a c t i v a t i o n , e . g . , - 8 e. u . to - 3 7 e . u . These va lues a r e i n good a g r e e m e n t w i t h those r e p o r t e d b y E l l i s and F r e y (80) f o r the t h e r m a l r e a r r a n g e m e n t of JK) to 91 (<-^  - 11.6 e. u.)/wbeie<.a c y c l i c t r a n s i -t ion state i s proposed, and by R o b e r t s et a l . (75) f o r the t h e r m a l r e a r -rangement of 2, 2 - d i m e t h y l - 1 - a c e t y l c y c l o p r o p a n e (95) to 5 - m e t h y l - 5 -h e x e n - 2 - o n e (96) (/V - 10 e . u . ) w h e r e an a l l y l i c enol i n t e r m e d i a t e i s i n -dicated. E l l i s and F r e y a lso suggested that there i s c o n s i d e r a b l e c o n t r i -but ion to the s t a b i l i z a t i o n of the t r a n s i t i o n state by a l l y l i c d e l o c a l i s a t i o n energy . T h i s is i n d i c a t e d b y the low a c t i v a t i o n e n e r g y , i . e. , 31 k c a l / m o l e , obta ined f o r the r e a c t i o n 90 -3*91 • h i c o m p a r i s o n , .the a c t i v a t i o n e n e r g y for the t h e r m a l r e a r r a n g e m e n t of v i n y l c y c l o pro pane to cyc lopentene , w h e r e a c y c l i c t r a n s i t i o n state i s p r o b a b l y not i n v o l v e d , w a s found to be about 50 k c a l / m o l e (97). In the present w o r k we have found heats of 95 96 - 47 -act ivat ion, f o r the t h e r m a l r e a r r a n g e m e n t of c i s - 2 - a l k y l c y c l o p r o p a n e - l -c a r b o x y j a t e s to be 25 to 38 k c a l / m o l e as a n t i c i p a t e d if the r e a r r a n g e -ment p r o c e e d s v i a a c y c l i c t r a n s i t i o n state. A n a d d i t i o n a l o b s e r v a t i o n i s apparent f r o m the k i n e t i c s tudies of the t h e r m a l r e a r r a n g e m e n t of the c i s - 2 - a l k y l c y c l o p r o p a n e s to t h e i r c o r r e s p o n d i n g " ^ ^ - u n s a t u r a t e d o l e f i n s . The ra tes of r e a r r a n g e m e n t have been found to be a f fec ted b y the n u m b e r of subst i tuents on the three r i n g c a r b o n a t o m s . S ince the bond breakage a l w a y s o c c u r e d on the C ( l ) C(2) b o n d , hence , i t i s p o s s i b l e to e x p l a i n the d i f f e r e n c e s i n r a t e s of re a r r a n g e m e n t i n t e r m s of s t e r i c ef fect upon the bond d i s s o c i a t i o n e n e r g y . It i s known that the d i s s o c i a t i o n of the c a r b o n - c a r b o n s ing le bond i n ethane d e c r e a s e s with ' the a d d i t i o n of a l i p h a t i c as w e l l as a r y l s u b s t i -tuents (95, 96). Suppose we c o n s i d e r the unsubst i tuted c y c l o p r o p a n e as a 1, 2 - d i s u b s t i t u t e d ethane, then the addi t ion of subst i tuents to the C - l anc C - 2 of the c y c l o p r o p a n e w o u l d reduce the bond d i s s o c i a t i o n e n e r g y of th C ( l ) - C ( 2 ) bond and thus i n c r e a s e the rate of r e a r r a n g e m e n t . F o r e x a m -p l e , the rate of t h e r m a l r e a r r a n g e m e n t i n c r e a s e s i n the o r d e r of 1, 2 - d i subst i tuted (37), 1 , 1 , 2 - and 1,2, 2 - t r i s u b s t i t u t e d (L8, 33_and35) and the 1, 1, 2, 2 - t e t r a s u b s t i t u t e d (32) c y c l o p r o p a n e s . 37 18 35 - 48 -O n the other hand, when subst i tuent i s then added to C - 3 , i t i s p o s s i b l e that the effect of subst i tuents on C - l and C - 2 i n r e d u c i n g the bond s t rength i s r e d u c e d due to bond w e a k e n i n g i n the C ( l ) - C ( 3 ) and C(2) -C(3) bonds . T h i s w o u l d account for the s l o w e r ra tes of t h e r m a l r e -a r r a n g e m e n t f o r the 1, 2, 3 - t r i s u b s t i t u t e d (36} and 1, 1, 2, 3 - t e t r a s u b s t i -tuted (38) c y c l o p r o p a n e s . A l t e r n a t i v e l y , the subst i tuent on C - 3 m i g h t affect the ease w i t h w h i c h the c a r b o n y l group on C - l and the m e t h y l group on C - 2 a p p r o a c h the t r a n s i t i o n state, g e o m e t r y . 36 38 One of the c i s - 2 - a l k y l c y c l o pro panes s tudied has a C - 2 e thy l c i s to the C - l c a r b o n y l , and this is m e t h y l t r a n s - 1 - m e t h y l - 2 - e t h y l c y c l o p r o -pane - 1 - c a r b o x y l a t e (33). T h e r e are two hydrogens w h i c h can t r a n s f e r to the c a r b o n y l oxygen to f o r m two i s o m e r i c Y,d - u n s a t u r a t e d o l e f i n s , n a m e l y , m e t h y l c i s - 2 - m e t h y l - 4 - p e n t e n o a t e (68) and m e t h y l t r a n s - 2 -m e t h y l - 4 - p e n t e n o a t e (69). H o w e v e r , they are not f o r m e d i n equal amounts - 49 -but i n the ra t io of 1:4.7 i n f a v o r of 69- A c o n s i d e r a t i o n of D r e i d i n g m o d e l s of the t r a n s i t i o n states 92 and 93 shows that 93 i s f a v o r e d , s ince 92 r e q u i r e s e c l i p s i n g of the m e t h y l group (on the C - 2 ethyl) and the C - 3 r i n g hydrogens w h e r e a s 93 does not. H M e / " " " C C ^ M e 33 H H M e Q r \ } 93 M e O 92 69 V 68 ; 0 2 M e : O z M e It i s of i n t e r e s t to c o m p a r e the rate of f o r m a t i o n of the t r a n s product (69) f r o m 33 w i t h that f o r the f o r m a t i o n of 31 f r o m 18. The X 11 s t e r e o c h e m i s t r y of 33 is quite s i m i l a r to that of 18 except that the h y -drogen for m i g r a t i o n is s e c o n d a r y i n the case of 33, and is p r i m a r y i n the case of 18. The rate of f o r m a t i o n of 69_ (tij2 a t 2 5 9 . 4 ° is 15.31 hrs . - 5 0 -i s about three t i m e s f a s t e r than the rate of f o r m a t i o n of 31 (tij2 a t 2 5 9 . 4 ° is 48.9 b r s . per h y d r o g e n * ). Thus a f a s t e r rate of r e a c t i o n i s obta ined f o r m i g r a t i o n of a s e c o n d a r y h y d r o g e n than a p r i m a r y h y d r o g e n as w o u l d be expec ted if bond b r e a k i n g of the C - H bond w e r e i m p o r t a n t i n the t r a n s i t i o n state, s u c h as 77 , as p r o p o s e d . To s u m up, a s e r i e s of 2 - a l k y l c y c l o p r o p a n e s have been p r e p a r e d . Those w i t h a C - l c a r b o n y l group c i s to a C - 2 a l k y l group w e r e found to r e a r r a n g e to t h e i r c o r r e s p o n d i n g Y,^-unsaturated o le f ins w h e n heated at t e m p e r a t u r e s r a n g i n g f r o m 2 4 0 ° to 3 0 0 ° . A l l o thers w e r e found t h e r m a l l y s tab le . The t h e r m a l r e a r r a n g e m e n t r e a c t i o n s w e r e c l e a r l y u n i m o l e c u l a r . These r e s u l t s suggest that the r e a r r a n g e m e n t r e a c t i o n s p r o c e e d b y an i n t r a m o l e c u l a r 1 ,5 -hydrogen t r a n s f e r v i a a s i x - m e m b e r e d t r a n s i t i o n state 77. T h i s i s suppor ted by the l a r g e negat ive e n t r o p i e s of a c t i v a t i o n and l o w beats of a c t i v a t i o n obta ined f r o m the k i n e t i c s t u d i e s . B y w a y of c o n c l u s i o n , this t h e r m a l r e a r r a n g e m e n t r e a c t i o n of a c i s - 2 - a l k y l c y c l o p r o p a n e to a % £ - u n s a t u r a t e d o l e f i n s h o u l d be of value i n s o l v i n g the s t e r e o c h e m i s t r y of i s o m e r i c c y c l o p r o p a n e s . In c o n t r a s t to those methods d e s c r i b e d i n the i n t r o d u c t i o n s e c t i o n of .this thes is , . the above method does not r e q u i r e the p r e s e n c e of both i s o m e r s . M c G r e e r et a l . , has e m p l o y e d this method s u c c e s s f u l l y i n d i s t i n g u i s h i n g the s t e r e o c h e m i s t r y of a n u m b e r of c y c l o p r o p a n e s . One example is that the C o r r e c t e d f o r the s t a t i s t i c a l l y fas ter rate due to the three a v a i l a b l e h y d r o g e n s . - 51 -s t e r e o c h e m i c a l a s s i g n m e n t to c i s - and t rans - 1 , 2 - d i m e t h y l - 1 - a c e t y l -c y c l o p r o p a n e (1 and 2) is made on the b a s i s that 2 r e a r r a n g e s t h e r m a l -l y to 3 - r n e t h y l - 5 - b e x e n - 2 - o n e ( 7 4 ) w h e r e a s 1 does not (5). S i m i l a r l y , the s t r u c t u r e of m e t h y l t r a n s - 1 , 2 - d i m e t h y l c y c l o p r o p a n e - 1 - c a r b o x y l a t e (18) i s c o n f i r m e d b y the fac t that i t r e a r r a n g e s t h e r m a l l y to g ive m e t h y l 2 - m e t b y l - 4 - b e x e n o a t e (31) (34). II-3: T H E R M A L , I S O M E R I Z A T I O N O F O L E F I N S T h e r m a l i s o m e r i z a t i o n of o le f ins and i d e n t i f i c a t i o n of products The i s o m e r i z a t i o n of u n s a t u r a t e d a c i d s , e s t e r s , ketones and n i t r i l e s to y i e l d e q u i l i b r i u m m i x t u r e s has been s tudied under a v a r i e t y of c o n d i t i o n s . R i n e h a r t et a l . (69, 81) have used s o d i u m g l y c o l a t e i n ethylene g l y c o l as c a t a l y s t , and L i n s t e a d et a l . (98) s i m p l y heated the ac ids i n " p u r e " state at t h e i r b o i l i n g p o i n t s . T h i s i s o m e r i z a t i o n is a l so p o s s i b l e -t h e r m a l l y at t e m p e r a t u r e s n e a r 300° w i t h or wi thout iodine c a t a l y s t , and y i e l d s a m i x t u r e of c(,/}- and - u n s a t u r a t e d e s t e r s . M c G r e e r et a l . (2) r e p o r t e d the t h e r m a l i s o m e r i z a t i o n of m e t h y l c i s -2-pentenoate (48) i n a s e a l e d tube at 25 0° for two weeks to give a m i x t u r e c o n s i s t i n g of 7% of 48, 48% of m e t h y l t r a n s - 2 - p e n t e n o a t e (49) and 45% of m e t h y l t r a n s - 3 - p e n t e n o a t e (94). H a v i n g d e m o n s t r a t e d a s i x - m e m b e r e d c y c l i c - \ _ / C ° 2 M e 2 5 0 ° _ — V _ / G Q 2 M e . _ _ _ / : C 2 M e _ / ~ C ° 2 M e 14 days '—^ ' / 48_ ! i l ( 7 % } 49(48%) _94 (45%) t r a n s i t i o n state f o r the i n t r a m o l e c u l a r 1 , 5 - h y d r o g e n t r a n s f e r i n the t h e r m a l r e a r r a n g e m e n t of the c y c l o p r o p a n e s e r i e s , we now w i s h e d to test w h e t h e r the f o r m a t i o n of (o,(( products m i g h t be a r e s u l t of a s i m i l a r c y c l i c h y d r o g e n t r a n s f e r p o s s i b l e f r o m the c i s ^ , _j - u n s a t u r a t e d es ter but not f r o m the t r a n s . T h e r e is come precedent f o r there are m a n y r e -act ions w h i c h have analogies i n the c y c l o p r o p a n e and o l e f i n s e r i e s w h e r e - 53 -the c y c l o p r o p a n e r i n g is p l a c e d i n a p o s i t i o n equivalent to the double bons , S a r e l and B r e u e r (82) showed that (^ - cyc lopropyls tyrene (97) u n -dergoes D i a l s A l d e r r e a c t i o n w i t h m a l e i c anhydr ide to give 4-phenylcy-c l o b e p t - 4 - e n e - l , 2 - d i c a r b o x y l i c anhydr ide (98). T h i s is an i l l u s t r a t i o n of \ 6 0 6 _97 98 the type of b e h a v i o r w h i c h suggests that cyclopropanes have some s i m i -l a r i t y to double bond i n t h e i r c h e m i s t r y . S i m i l a r l y , the r e a c t i o n of a c e t y l c y c l o p r o p a n e (99) and phosphorous p e n t a c b l o r i d e to y i e l d 2 , 5 - d i -c h l o r o - 2 - p e n t e n e (100) i n d ica tes that the c y c l o p r o p a n e r i n g acts l i k e a C O M e + P C 1 5 ) C I 99 100 double bond i n a s t r a i g h t c h a i n compound so that a n o r m a l d i c b l o r i d e is i n i t i a l l y f o r m e d w h i c h then r e a r r a n g e s to give 100 (83). A c l o c e l y r e l a t e d i s o m e r i z a t i o n r e a c t i o n is the t h e r m a l i n t e r -c o n v e r s i o n o£_c_ is -4 -methyl - l , 3-pentadiene (104) to p i s -2 - m e t h y l - 1 , 3 -pentadiene (106) (99). The r e a c t i o n i n v o l v e s the o v e r a l l 1 , 5 - h y d r o g e n t r a n s f e r w i t h concomitant m i g r a t i o n of both c a r b o n - c a r b o n double bonds v i a a s i x - m e m b e r e d c y c l i c t r a n s i t i o n state, 105. T h i s shows that 1 , 5 -- 54 -104 105 106 h y d r o g e n t r a n s f e r is p o s s i b l e i n analogous compounds such as ck,p-u n s a t u r a t e d e s t e r s provided that they have the c o r r e c t g e o m e t r y . B u t l e r et a l . (94) i n a s tudy of the t h e r m a l i s o m e r i z a t i o n of m e t h y l c i s - c r o t o n a t e to m e t h y l t r a n s - c r o t o n a t e has a l r e a d y noted no evidence that the s m a l l amout of i s o m e r f o r m e d was f o r m e d p r e f e r e n t i a l l y f r o m the c i s than the t r a n s . T h i s s y s t e m i s not h o w e v e r i d e a l due to the l o w e q u i l i -b r i u m value of the i s o m e r and s tudies w e r e t h e r e f o r e d i r e c t e d t o w a r d s the e s t e r s w i t h e t h y l and i s o p r o p y l groups on the ^ - c a r b o n w h i c h at e q u i l i b r i a - give m o r e of the ^6,Q i s o m e r (2, 69, 81). F r o m the p r e v i o u s s tudy f o u r i s o m e r i c p a i r s of e(,|3-unsaturat-ed e s t e r s w e r e a v a i l a b l e as has been d e s c r i b e d e a r l i e r and these are l i s t e d i n Tab le II (p. 14 ). These e s t e r 3 w e r e i s o m e r i z e d t h e r m a l l y at t e m p e r a t u r e s r a n g i n g f r o m 2 4 0 ° to 300° R e s u l t s show that a f ter each of these o ( ,p -unsa tura ted e s t e r s was i s o m e r i z e d , the p r o d u c t m i x t u r e u s u a l l y c o n s i s t e d of, the i n i t i a l e s t e r , i ts g e o m e t r i c i s o m e r and the c o r -r e s p o n d i n g i s o m e r . These |G J\ - u n s a t u r a t e d esters were p r e p a r e d and i s o l a t e d f r o m the t h e r m a l i s o m e r i z a t i o n of t h e i r c i s i s o m e r s . ( F i g u r e 9). T h e y w e r e c h a r a c t e r i z e d b y e l e m e n t a l ' m i c r o a n a l y s e s and s p e c t r a l (N. M . R . and I. R . ) ana lyses and the l a t t e r a r e d i s c u s s e d b e l o w . - 55 -C O z M e , C 0 2 M e 42 + yr=r< + \ / \ ' \ / x C O z M e 42 '43 101 J , C 0 2 M e C 0 2 M e s* . 44 + = / + x C 0 0 M e ' 2 J 44 45 102 C O z M e C 0 2 M e C O , M e =( e - 4 6 + _ y = ^ + V - / 46 47 103 C O M e f 2 i V i e 2 - 48 + + ~ \ / C O . M e _ , / 2 , —;v f 0 2 M e 48 ._49 _94 F I G U R E 9 P r o d u c t s f r o m the t h e r m a l i s o m e r i z a t i o n of c i s - 2 -pentenoates M e t h y l 2, 4 - d i m e t h y l - 3 - p e n t e n o a t e (101) w a s c h a r a c t e r i z e d b y i ts N . M . R . s p e c t r u m . It shows a s ing le t at 6.38 X due to the e s t e r m e t h y l , a doublet at 8.84 X (J^-7.1 c .p .s . ) due to the C - 2 m e t h y l w h i c h be ing s p l i t b y the C - 2 methine h y d r o g e n w h i c h i n turn-; a p p e a r e d as a m u l t i p l e t at 6.76 X- The C - 4 m e t h y l s showed two doublets at 8.34 X and 8.28 X ( J— 1.4 c . p . s . f o r both) p r o b a b l y s p l i t b y the C - 3 o l e f i n i c h y d r o -gen w h i c h a p p e a r e d as a m u l t i p l e t at 4.89 X. M e t h y l 4 - m e t h y l - 3 - p e n t e n o a t e (102) showed a N . M . R . peak at 6 . 4 0 X due to the es ter m e t h y l . Two s l i g h t l y b r o a d e n e d s ing le t s at 8.26 X - 56 -and 8.37 T are a s s i g n e d to the C - 4 m e t h y l s . The C - 2 methylene h y d r o -gens showed a b r o a d doublet at 7.08 X (J^-7.2. c .p . s . ) and the C - 3 o l e f i n i c h y d r o g e n showed a m u l t i p l e t at 4.75 T . M e t h y l t r a n s - 2 - m e t h y l - 3 - p e n t e n o a t e (103) was a s s i g n e d the t r a n s g e o m e t r y on the b a s i s that i t showed an I. R . band at 971 c m ~ ^ due to the two o l e f i n i c hydrogens v i b r a t e i n opposite d i r e c t i o n (29). The N . M . R. s p e c t r u m of 103 shows two doublets one at 8.81 X ( J — 7 . i c .p .s . ) due to the C - 2 m e t h y l w h i c h w a s s p l i t b y the C - 2 me thine h y d r o g e n at 7.0 X ( m u l t i p l e t ) , the other at 8.31 T ( J ^ 4 . 6 c .p .s . ) due to the C - 4 m e t h y l w h i c h w a s s p l i t b y the C - 4 v i n y l h y d r o g e n . The l a t t e r and the C - 3 v i n y l h y d r o g e n showed a m u l t i p l e t c e n t r e d at 4.5 1 X. The c o m p o u n d m e t h y l 3-pentenoate (94) had been c h a r a c t e r i z e d p r e v i o u s l y (2). The data f o r the t h e r m a l i s o m e r i z a t i o n r e a c t i o n s of the m e t h y l 2 - and 3-pentenoates at v a r i o u s t e m p e r a t u r e s and d u r a t i o n s are l i s t e d i n T a b l e s V I , V I I , V H I and LX. In these tab les , the data f o r the e q u i l i b r i u m studies are al3o i n c l u d e d . T h e y show the f o l l o w i n g r e s u l t s w h i c h a r e c o m m o n to a l l e s t e r s s tudied . The c i s o(,6 i s o m e r s t h e r m a l l y i s o m e r i z e d to give the t rans C\,f6 i s o m e r s and the 8,% i s o m e r s . The r e l a t i v e ' r a t e s of f o r m a t i o n w e r e f a s t e r f o r the i%b i s o m e r s than the trang o{',->' i s o m e r s . A s a r e s u l t , the r e l a t i v e amounts of the p . iT i s o m e r s b u i l t up to m a x i u m values - 57 -T A B L E V I . T h e r m a l r e a r r a n g e m e n t of m e t h y l 2, 4 - d i m e t h y l - 2 - and 3-pentenoates — ^ C O z M e / C ° 2 M e € 0 2 M e 42 43 101 I n i t i a l o l e f i n r u n no. t i m e (hr. ) temo. (°C) . c i s t r a n s i / c i s - 35 30 2 8 3 . 7 ° 28.3 2.0 69.7 51 17 2 9 7 . 4 ° 17.3 1.5 81.2 59 83 2 9 7 . 4 ° 9.6 4.2 86.2 c i s - ^ . / s i 59 151 297. 4° 8.6 6.7 84.7 77% cis.-o()/3 & 64 290 297 .4° 7.7 28.7 63.6 23% t r a n s ,6 64 35 3* 2 9 7 . 4 ° 7.9 28.6 63.5 t r a n s - ^, /j 59 83 297 .4° 2.8 74.8 22.4 t r a n s trans-,->',/•! 59 151 2 9 7 . 4 ° 2.4 69.6 27.0 59 174 2 9 7 . 4 ° 3.7 68.0 28.3 36 36 283 .7° 2.3 -- 97.7 36 86 283 .7° 5.1 -- 94. 9 36 155 283 .7° 6.5 -- 93.5 59 83 297 .4° 6.7 -- 93.3 I 59 151 297 .4° 7.7 0.5 91-8 E q u i l i b r i u m at ta ined - - 7.9% i _cis_- >>., b s , 28.6%) t r a n i i - Ob •:> and 63.5% b - 58 -T A B L E V I I T h e r m a l r e a r r a n g e m e n t of m e t h y l 4 - m e t h y l - 2 - and 3-pentenoates ? M e -{ yCOzMe 2 M e 44 45 102 I n i t i a l o l e f i n r u n no. t i m e (hr. ) t e m p . (°C) c i s -d,p t rans -d,fb £ Y c i s ;-g<,|3 56 7 2 5 9 . 4 ° 15.7 4.8 79.5 63 4 2 9 7 . 4 ° 1.9 Z..3 95.8 c i g /3 63 6 2 9 7 . 4 ° 1.7 4.0 94.3 ci_s-c{,^ 63 24 2 9 7 . 4 ° 1.8 4.7 93.5 cis-^,/3 63 40 2 9 7 . 4 ° 1.7 7.3 91. 4 75% c i s - 5 ^ & 65 211* 2 9 7 . 4 ° 1.5 17.9 80.6 25% trans -sk,p 65 290* 2 9 7 . 4 ° 1. 5 17.7 80.8 cis-^,/3 66 259* 2 9 7 . 4 ° 1. 5 17. 7 80.8 c i ? 66 336* 2 9 7 . 4 ° 1. 5 17.6 80.9 t r a n s - r A $ 66 25 9* 2 9 7 . 4 ° 1.5 17.8 80.7 t rans —A A 66 336* 2 9 7 . 4 ° 1.5 . 17.8 80.7 t r i m s - 4 , <3 63 4 2 9 7 . 4 ° - - 91.6 8.4 trans-^,,3 63 6 2 9 7 . 4 ° — 90.0 10.0 Lrans-4-^ 63 24 2 9 7 . 4 ° - - 82.1 17.9 t r a n s 63 40 2 9 7 . 4 ° t race 78.1 21.9 63 4 2 9 7 . 4 ° 1.8 2,1 96.1 63 40 2 9 7 . 4 ° 1.5 9.3 89.2 ( io% Q ) 63 4 2 9 7 . 4 ° 1.7 2.6 95.7 * E q u i l i b r i u m at ta ined — 1.5% cis-<?(,,6 , 17.7% trans - ^ ,8 and 80.8% - 59 -T A B L E VII I T h e r m a l r e a r r a n g e m e n t of m e t h y l 2 - m e t h y l - 2 - and 3-pentenoates _ . , C 0 0 M e \ / £• — \ 2 M e / — x c o 2 M e 46 47 103 I n i t i a l o l e f i n r u n no. t i m e (hr. ) t e m p . (°C) c i s - / , ^ t rans -50 4 2 9 7 . 4 ° 81.9 7.7 10.4 50 6 2 9 7 . 4 ° 73.1 10.5 16.4 50 10 2 9 7 . 4 ° 62. 0 14.8 23.2 50 21 2 9 7 . 4 ° 41.8 21.7 36.5 Q i s - ^ , / 5 58 83 2 9 7 . 4 ° 18.5 39.7 41.8 58 174* 2 9 7 . 4 ° 16.2 45.9 37 .9 c i s - ^ , ^ 58 200* 2 9 7 . 4 ° 16.3 45.8 37.9 t r a n s 58 83 2 9 7 . 4 ° 10.3 67.4 22.3 t r a n s , '3 58 151 2 9 7 . 4 ° 11.6 61.8 26.6 t r a n s . - J , / ^ 58 174 2 9 7 . 4 ° 12.6 58.8 28.6 E q u i l i b r i u m at ta ined - - 16.2% cis-o( 6 , 45.9% trans-c(,$ and 37.9% /3,t - 60 -T A B L E IX T h e r m a l re.arran^ jement of m e t h y l 2 - and 3-pentenoates M e y C 0 2 M e _ _ / \ / C O £ M e 48 49 94 I n i t i a l o l e f i n r u n n o . t i m e (hr. ) t emp. , o „ . . c i s - o i f l I C) [ t r a n s -J ,f\ c i s - ^ , / ^ 8 5 25 9 .4° 86.4 1.8 11.8 8 22 25 9 .4° 46.4 6.0 47.4 8 61 2 5 9 - 4 ° 13.7 12.4 73.9 c±s_-d M >;< 336 25 0° 7 48 45 t r a n s - d 336 25 0° 7 47 46 trans-d ,{i 10 17 2 5 9 . 4 ° 1. 5 89.5 9.0 10 26 2 5 9 . 4 ° 2.2 81.1 16.7 t r a n s - J ,/3 10 64 2 5 9 . 4 ° 3.9 61.3 34.8 10 17 25 9 .4° 9.2 11.7 79.0 t 10 26 2 5 9 . 4 ° 8.6 16.0 75.4 h y 10 41 2 5 9 . 4 ° 8.0 26.8 65.2 I 10 64 25 9 .4° 7.7 31. 1 61.2 * See r e f e r e n c e 2:, e q u i l i b r i u m at ta ined - - 7% c is - o(, ,6, 48% t rans -c(,S> and 45% /3,<{ - DI -100,. % 9 0 L | 8 0p-.; 1 70: \ 60L I 501 40L 30\ O A I i o ! j 3m. ye*0* 0. e q u i l i b r i u m va lues / — 7 C C ^ M e C O , M e C G ^ M e 20 40 60 80 100 120 140 160 180 340 t (hr) T G U R E 10 - E q u i l i b r a t i o n of m e t h y l 2- and 3 -pentenoates - 62 -( F i g u r e 10) w h i c h w e r e above t h e i r e q u i l i b r i u m values w h e r e a s the r e l a t i v e amounts of the t rans oi,£ i s o m e r s w e r e a l w a y s be low t h e i r e q u i l i b r i u m v a l u e s . A f t e r r e a c h i n g a m a x i u m , the /SX i s o m e r s w o u l d d e c r e a s e and the t r a n s cl,fe i s o m e r s w o u l d i n c r e a s e t o w a r d the e q u i l i -b r i u m . F o r e x a m p l e , m e t h y l c i s - 4 - m e t h y l - 2 - p e n t e n o a t e (44) y i e l d e d (run no . 63, Table VII) , a f ter heat ing at 2 9 7 . 4 ° f o r 4 h o u r s , 2. 3% of the t rans c(>f' i s o m e r (45) and 95.8% of the i s o m e r (102) c o m p a r e d to t h e i r e q u i l i b r i u m va lues of 17.8% and 80.7% r e s p e c t i v e l y . The t rans o(,j3 i s o m e r s r s . o m e r i z e d to give the c i s ci,ji> A y i s o m e r s and the p , u i s o m e r s , s u c h that i n m o s t c a s e s these two i s o m e r s w e r e f o r m e d i n a ra t io c l o s e to t h e i r e q u i l i b r i u m r a t i o . F o r e x a m p l e , the m e t h y l t r a n s - 2 - m e t h y l - 2 - p e n t e n o a t e (47) y i e l d e d • m i x -ture a -o f "the ji,"^ i s o m e r (103) and the c i s ;j\J) i s o m e r (46) i n the r a t i o ( run 58, Tab le VIII) of 2.16, 2.30 and 2.27 at 83, 151 and 174 h o u r s r e s p e c t i v e l y . The ft>,$ i s o m e r s i s o m e r i z e d to give the c i s c/,(/3 and t rans t>J,|5) i s o m e r s i n u n p r e d i c t a b l e p r o p o r t i o n i n i t i a l l y . A s the heat ing w a s p r o l o n g e d , the c i s i s o m e r s r e a c h e d the e q u i l i b r i u m p r o p o r t i o n r e l a t i v e to the i s o m e r s f i r s t . In the case of m e t h y l 2, 4 - d i m e t h y l -3-pentenoate (101), o n l y the c i s C\,p i s o m e r (42) w a s f o r m e d i n the i n i t i a l stages of the r e a c t i o n (run no. 36 & 59, Table VI) and the ra t io of 42/101 had a l m o s t r e a c h e d i ts e q u i l i b r i u m value be fore t r a c e s of the t rans o<\B i s o m e r (43) began to f o r m . - 63 -F r o m the data shown i n the tab les , i t can be seen that the r e l a -t ive ra tes of i s o m e r i z a t i o n r e a c t i o n s of the c i s i s o m e r s w e r e m u c h f a s t e r than the t r a n s c( ,^ i s o m e r s and the i s o m e r s . F o r e x a m p l e , a f t e r 4 h o u r s at 2 9 7 . 4 ° (run n o . 63, Table VII) o v e r 99% of m e t h y l c i s -4 - m e t h y l - 2 - p e n t e n o a t e (44) h a d i s o m e r i z e d , w h e r e a s o n l y 10% and 20% of the t r a n s 0?,ji i s o m e r (45) and the p>X i s o m e r (102) r e s p e c t i v e l y had i s o m e r i z e d (the f i g u r e s of percentage quoted h e r e h a d been c o r r e c t -ed a f te r t ak ing into account the e q u i l i b r i u m va lues of the three i s o m e r s ) . S tudies w e r e c a r r i e d out to d e t e r m i n e the d i s t r i b u t i o n of the three i s o m e r s at e q u i l i b r i u m . F o r each o l e f i n s y s t e m , a l l three i s o m e r s h a d b e e n u s e d i n d i v i d u a l l y as the i n i t i a l o l e f i n f r o m w h i c h the point of e q u i l i b r i u m w a s r e a c h e d . In s o m e cases w h e n e i t h e r the t r a n s d,p i s o m e r o r the jS,"^ i s o m e r w a s u s e d , e q u i l i b r i u m c o u l d not be r e a c h e d due to the s l o w rate of i s o m e r i z a t i o n . H i g h e r t e m p e r a t u r e s c o u l d not . b e u s e d to o v e r c o m e this as ex tens ive p y r o l y s i s of the compounds into l o w e r f r a g m e n t s took p lace at t e m p e r a t u r e s above 3 2 5 ° . To o v e r c o m e this d i f f i c u l t y , m i x t u r e s of the i s o m e r s at c l o s e to e q u i l i b r i u m c o m p o s i t i o n w e r e u s e d and e q u i l i b r i u m w a s c o n s i d e r e d r e a c h e d w h e n two o r m o r e runs of d i f f e r e n t t i m e i n t e r v a l s gave e s s e n t i a l l y the same p r o p o r t i o n of i s o m e r s . - 64 -K i n e t i c s tudies R e s u l t s of the t h e r m a l i s o m e r i z a t i o n r e a c t i o n s d i s c u s s e d i n the previous . ' . sect ion indica te that the c i s o/,/3 i s o m e r s i s o m e r i z e d to the /3,Q i s o m e r s f a s t e r than to the t r a n s C*j,p i s o m e r s , i n the case of m e t h y l c i s - 2 , 4 - d i m e t h y l - 2 - p e n t e n o a t e (42), the r e l a t i v e ra tes of f o r m a -t i o n f o r the i s o m e r w a s so m u c h f a s t e r than that f o r the t r a n s d,p i s o m e r that the r a t i o of |o,l> / t r a n s <^,|3 w a s 54:1 a f ter 90%v;of 42 h a d i s o m e r i z e d " (run no . 51, T a b l e V I ) . T h i s i s a l so t rue f o r m e t h y l c i s - 4 -m e t h y l - 2 - p e n t e n o a t e (44) w h i c h i s o m e r i z e d to the fi>,\ i s o m e r and the t r a n s Q^o i s o m e r i n the ratio, of 41:1 a f te r 99%^ of 44 had i s o m e r i z e d data ( run no. 63, Tab le VI I ) . T h e s e j i n d i c a t e i n a q u a l i t a t i v e w a y that the i s o m e r i z a t i o n of the c i s d i s o m e r to the |3-,^  i s o m e r m i g h t be f o l l o w e d k i n e t i c a l l y independent : of the c i s ()\ to t rans o r t rans 0^,B to jS,^  i s o m e r i z a t i o n paths.. Consequent ly , the k i n e t i c s of t h e r m a l i s o m e r i z a t i o n r e a c t i o n s of these two c i s - 2 - p e n t e n o a t e s (42 and 44) to t h e i r c o r r e s p o n d i n g 3-pentenoates (101 and 102) w e r e s tudied at v a r i o u s t e m p e r a t u r e s . The k i n e t i c data obta ined gave good s t r a i g h t l i n e s w h e n plot ted us ing the f i r s t - o r d e r rate l a w . The rate constants (k) and h a l f - l i v e s ( t ^ ^ °^ these t h e r m a l i s o m e r i z a t i o n r e a c t i o n s w e r e c a l c u l a t e d f r o m f i r s t - o r d e r rate plots of l o g a Q / ( a 0 - x ) v e r s u s t i m e t ( F i g u r e s 11 and 12). T h e i r heat of a c t i v a -te C o r r e c t e d a f ter taking into account the e q u i l i b r i u m value of the c i s 0^  ,p i s o m e r . - 66 -0 4 8 12 16 20 24 t (hr) F I G U R E 12 - F i r s t - o r d e r rate plots f o r the t h e r m a l i s o m e r i z a t i o n of 44 - 67 -- 69 -T A B L E X K i n e t i c data of the t h e r m a l i s o m e r i z a t i o n of m e t h y l c i s - 2 , 4 - d i m e t h y l -2-pentenoate (42) —<^  , C 0 2 M e 42 R u n n o . t e m p . ( °C) k x I O " 5 (sec ) tl/2 A H * ( k c a l ) i m o l e ( h r " 1 ) A S * ( e . u . ) at 2 7 2 . 2 ° 32 2 7 2 . 2 ° 0.91 21.1 33 2 7 2 . 2 ° 0.90 21.3 1 - 4 9 . 9 34 2 8 3 . 7 ° 1.26- 15.3 17.9 35 2 8 3 . 7 ° 1:28 15.1 51 2 9 7 . 4 ° * 2.98 6.5 V A f t e r t a k i n g into account the e q u i l i b r i u m values of the three i s o m e r s , th i s k b e c o m e s 3.021 (1.4% di f f . ). See A p p e n d i x f o r c a l c u l a t i o n . T A B L E X I K i n e t i c data of the t h e r m a l i s o m e r i z a t i o n of m e t h y l c i s - 4 - m e t h y l -2-pentenoate (44) 44 M e R u n n o . t e m p . ( °C) k x 10-( s e c -• 5 t l / 2 (hr~ 55 2 4 0 . 4 ° 1.86 10.4 .5 7 2 5 2 . 0 ° 4 .28 * 4.5 56 2 5 9 . 4 ° 7.06- 2.7 m o l e at 25 9 . 4 ° 1 1 37.5 - 8 . 2 A f t e r tak ing into account the e q u i l i b r i u m values of the three i s o m e r s , th i s k b e c o m e s 7.222 (2.2% dif f . ). See A p p e n d i x f o r c a l c u l a t i o n . 1 • * The e s t i m a t e d •maxitvxum. e r r o r s i n A H and A S a r e ± 1 0 % - 70 -t i o n ( A H t ) arid entropies of a c t i v a t i o n ( A S V ) w e r e c a l c u l a t e d f r o m plots of l o g k / T v e r s u s 1 / T ( F i g u r e s 1 3 and 1 4 ) . These k i n e t i c r e s u l t s are l i s t e d ha Tables X and X I . D i s c u s s i o n of r e s u l t s L e t us now c o n s i d e r the m e c h a n i s m f o r the t h e r m a l i s o m e r i z a -t i o n of the u n s a t u r a t e d e s t e r s . T h e r e are s i x d i f f e r e n t steps to be c o n -s i d e r e d as shown b e l o w . R e s u l t s of the t h e r m a l i s o m e r i z a t i o n and k i n e t i c ci_s_ i,fs ;====b=^ t rans ^ ,(p 6 A s tudies i n d i c a t e ' that the c i s '^,'3 i s o m e r s i s o m e r i z e d to the (6,0' i s o m e r s (k-,) Tas ter than to the t r a n s <X ,,5 i s o m e r s (k^) f o r the s y s t e m s w i t h a /5 - i sopropyl g r o u p and that a l l o ther steps a r e v e r y s l o w . We can c o n s i d e r three m e c h a n i s m s i n w h i c h a c i s (X - u n s a t u -r a t e d e s t e r can i s o m e r i z e to i t s c o r r e s p o n d i n g |3,o* i s o m e r . These a r e 'the base c a t a l y s e d i s o m e r i z a t i o n , the f ree r a d i c a l r e a r r a n g e m e n t and 'die i n t r a m o l e c u l a r 1, 5 - h y d r o g e n t r a n s f e r v i a a s i x - m e m b e r e d c y c l i c t r a n s i -t i o n state. The base c a t a l y s e d i s o m e r i z a t i o n ( 8 4 ) i n v o l v e s the f o r m a t i o n of an enolate i o n of the c i s 0\,j>-unsaturated es ter , 1 0 8 , b y proton a b s -t r a c t i o n b y the b a s e . T h i s enolate i o n ( 1 0 3 ) w o u l d then r e a r r a n g e to give - 71 -2 x- i iy - ° M e ~~^ R z \ // ° M e — ^ /3»o 107 108 the y ^ , ^ i s o m e r . S ince a base i s d i r e c t l y i n v o l v e d i n the i s o m e r i z a t i o n , i t s p r e s e n c e w o u l d be expec ted to s t r o n g l y af fect the ra te of i s o m e r i z a -t i o n . T h i s w a s not o b s e r v e d on o u r k i n e t i c s tudies f o r w i t h the a d d i t i o n of 10% p y r i d i n e into a s a m p l e , there w a s no s i g n i f i c a n t change i n the rate of i s o m e r i z a t i o n of the i s o m e r (Table V I I , r u n no . 63) . We f u r t h e r note that K i n s t ie r e p o r t e d (69) a 0,c? i s o m e r , 113 , as a m a j o r : p r o d u c t at e q u i l i b r i u m f o r the base c a t a l y s e d i s o m e r i z a t i o n of e thy l c i s -2 , 4 - d i r n e t h y l - 2 - p e n t e n o a t e u s i n g s o d i u m g lyco la te i n ethylene g l y c o l at 1 9 5 ° and suggested that 113 i s f o r m e d f r o m the i s o m e r (109) . The I ILL \ 109 110 113 112 m e c h a n i s m p r o p o s e d i n v o l v e s the f o r m a t i o n of an enolate i o n of the , i s o m e r , 110, f o l l o w e d b y p r o t o n a b s t r a c t i o n by oxygen to f o r m an a l l y l i c c a r b a n i o n 111 , w h i c h then g ives the X<£ i s o m e r (113) . T h e r e i s no i n -- 72 -d i c a t i o n of the f o r m a t i o n of \,Q. i s o m e r s i n the p r e s e n t s tudies a l though these w e r e l o o k e d f o r even at long r e a c t i o n t i m e s . We thus conc lude that base c a t a l y s i s m e c h a n i s m i s not i m p o r t a n t i n o u r s y s t e m . If the i s o m e r i z a t i o n took place b y a f ree r a d i c a l m e c h a n i s m , one w o u l d expect the f o l l o w i n g r e s u l t s . F i r s t l y , the rate of i s o m e r i z a t i o n w o u l d be a f fec ted b y the p r e s e n c e of oxygen s ince i t i s a f r e e r a d i c a l i n h i -b i t o r ( 9 3 ) . Secondly , both the c i s and the t rans C\,p i s o m e r s w o u l d g ive the i s o m e r at c o m p a r a b l e ra tes and the i s o m e r w o u l d g ive both the c i s and the t r a n s i s o m e r s at c o m p a r a b l e ra tes s i n c e the mecha: -"t n i s m to e i t h e r w o u l d be expec ted to r e q u i r e s i m i l a r a c t i v a t i o n e n e r g i e s . A l l these points a r e i n c o n s t r a s t w i t h o u r o b s e r v a t i o n s w h i c h have found the rate independent of the p r e s e n c e of oxygen, the c o n v e r s i o n of the c i s i s o m e r to the p , 0 i s o m e r f a s t e r than that of the t r a n s 0 ,^0 to the i s o m e r (runs 3 5 and 5 9 , Tab le V I ) and the c o n v e r s i o n of the p>,ty i s o m e r to the c i s o(,^ i s o m e r f a s t e r than the i s o m e r to the t r a n s QI,^, i s o m e r ( run 3 6 , T a b l e V I ) . We therefore•. conclude that a f ree r a d i c a l m e c h a n i s m i s not i m p o r t a n t . A c y c l i c m e c h a n i s m s i m i l a r to that d i s c u s s e d e a r l i e r f o r the t h e r m a l r e a r r a n g e m e n t of m e t h y l c i s - 2 - a l k y l c y c l o p r o p a n e - 1 - c a r b o x y -late s does s e e m to s a t i s f a c t o r i l y e x p l a i n the r e s u l t s of the t h e r m a l i s o m e r i z a t i o n of - u n s a t u r a t e d e s t e r s . The s i x - m e m b e r e d c y c l i c t r a n s i t i o n state, 114, i s shown be low, and w o u l d l e a d to the enol 115. such a h y d r o g e n t r a n s f e r can o n l y take place if the a l k y l group b e a r i n g - 73 -R 2 q y^-OMe ^ R 2 C N i - O M e 107 114 9 H R 2 C = / X C 0 2 M e «- R 2 ^ // O M e 116 • 115 the h y d r o g e n to be t r a n s f e r r e d and the c a r b o x y l a t e g r o u p a r e c i s to each o ther . T h e r e f o r e , o n l y the c i s o ( ,^ -unsaturated e s t e r s can i s o m e r i z e to the i s o m e r s , and v ice v e r s a . The enolene type i n t e r m e d i a t e a l though not expected to be stable w o u l d be expected to be a c c e s s a b l e i n a p r e - e q u i l i b r i u m steps f o r the .6,5 to c i s C>V,Q i s o m e r i z a t i o n (75). In our data the c i s o r i e n t a t i o n is c l e a r l y n e c e s s a r y f o r the /3 - i sopropyl a c r y l a t e s and is i n d i c a t e d i n the )3-ethyl a c r y l a t e s . T h i s data i s , i l l u s -t r a t e d g r a p h i c a l l y i n F i g u r e 10 (p. 61) to show the fast b u i l t up of i s o m e r f r o m the c i s d\,B i s o m e r . No such d i s t i n c t i o n w a s found for the / J - m e t h y l s e r i e s (94) i n the gas phase. It i s s i g n i f i c a n t however that for a l l of these s y s t e m s p,o i s o m e r s appear i n the f i n a l e q u i l i b r i u m m i x t u r e . I s o m e r i z a t i o n of a 6,0 o l e f i n at 297 shows c i s to t rans i n t e r c o n v e r s i o n but no chain i s o m e r i z a t i o n . F i n a l l y the l a r g e negative entropies of a c t i v a t i o n i n the (5 - isopropyl s e r i e s is f u l l y i n l ine w i t h the p r o p o s a l of a c y c l i c t r a n s i t i o n state for the i s o m e r i z a t i o n r e a c t i o n s . The 1 ,5 -hydrogen t r a n s f e r m e c h a n i s m d i s c u s s e d above p r o v i d e s - 74 -f o r the f o r m a t i o n of />X i s o m e r s but not f o r i s o m e r s , i n at l e a s t one case noted above i f a path f o r f o r m a t i o n of the i s o m e r w e r e a v a i l a b l e then i t should appear i n a p p r e c i a b l e quant i t ies at e q u i l i b r i u m . T h i s w a s not o b s e r v e d . It has been d i s c u s s e d above that the 1, 5 - h y d r o g e n t r a n s f e r r e -a c t i o n i n the 0(,^ - u n s a t u r a t e d e s t e r s r e q u i r e s a c i s r e l a t i o n s h i p between the j3>-alkyl subst i tuent and the e s t e r c a r b o n y l group . The nature of the f>-alkyl subst i tuent affects the r e l a t i v e i m p o r t a n c e of the 1 , 5 - h y d r o g e n t r a n s f e r r e a c t i o n , i . e . , the i s o m e r i z a t i o n c o f c i s QJ,J8 to p,^ and the c i s ,(J to t rans o^,|J. The rate of the i s o m e r i z a t i o n of the c i s o(,3 to a ppears to i n c r e a s e w i t h the change i n ^5-alkyl subst i tuent f r o m m e t h y l to e t h y l to i s o p r o p y l . F o r the c y c l i c 1, 5 - h y d r o g e n t r a n s f e r , a t e r t i a r y h y d r o g e n m i g h t be expected to be m o s t r e a d i l y t r a n s f e r r e d s ince a s e c o n d a r y h y d r o g e n has been o b s e r v e d i n the f i r s t s e c t i o n of this thes i s to be m o r e r e a d i l y t r a n s f e r r e d than a p r i m a r y h y d r o g e n . A t the -same t ime the c i s t o t rans £)j,p i s o m e r i z a t i o n appears to become s l o w e r as the |>'-alkyl subst i tuent i s changed f r o m m e t h y l to e thyl to i s o p r o p y l . It i s p o s s i b l e that i n the c i s <j\,p to t rans 2 o(,,i3 i s o m e r i z a t i o n the h y b r i d i z a t i o n of the carbons changed f r o m sp to s u 3 , and as the s i z e of f>-alkyl is i n c r e a s e d , this r e a c t i o n is s t e r i c a l l y i n h i b i t e d . Thus the rate of the c i s d$ to t rans d,k i s o m e r i z a t i o n is f . I r e d u c e d and as a r e s u l t , the i s o m e r i z a t i o n of c i s c{,^ > to i s o b s e r v e d as an i s o l a t e d step. - 75 -To conc lude , it has been shown that c i s Q( , ft - u n s a t u r a t e d e s t e r s c a n be i s o m e r i z e d t h e r m a l l y to t h e i r {% ,Y i s o m e r s . The i s o m e r i z a t i o n r e a c t i o n proceeds b y an i n t r a m o l e c u l a r 1, 5 - h y d r o g e n t r a n s f e r v i a a s i x -m e m b e r e d c y c l i c t r a n s i t i o n state, 114. A l t h o u g h this step has been 114 d e m o n s t r a t e d i n d e t a i l o n l y f o r compounds w i t h a p - i s o p r o p y l group, i t i s a n t i c i p a t e d to be i m p o r t a n t f o r the t h e r m a l e q u i l i b r a t i o n of u n s a t u -r a t e d e s t e r s , ketones and a l d e h y d e s . - 76 -i n . E X P E R I M E N T A L , G e n e r a l s tatement A l l b o i l i n g points are u n c o r r e c t e d and m o s t of them w e r e d e -t e r m i n e d b y the m i c r o i n v e r t e d c a p i l l a r y method. R e f r a c t i v e i n d i c e s w e r e d e t e r m i n e d at t e m p e r a t u r e s ranging f r o m 2 0 ° to 2 7 ° us ing an Abbe R e f r a c t o m e t e r . I n f r a r e d s p e c t r a w e r e m e a s u r e d w i t h a P e r k i n - E l m e r M o d e l 2 1 D B s p e c t r o m e t e r f i t t ed w i t h s o d i u m c h l o r i d e o p t i c s . S a m p l e s w e r e d i s s o l v e d i n c a r b o n t e t r a c h l o r i d e i n 5 - 10% s o l u t i o n . M o s t i n f r a r e d bands a r e c a l i b r a t e d us ing the 1603 c m " * band of the polyethylene f i l m as s t a n d a r d . N u c l e a r magnet i c resonance 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 A - 6 0 s p e c t r o m e t e r a n d / o r on a V a r i a n A s s o c i a t e s H A - 1 0 0 s p e c t r o m e t e r b y M r s . A . B r e w s t e r , M i s s C . B u r f i t t and M r . R. B u r t o n of this depar tment . The double resonance s p e c t r a w e r e m e a s u r e d on the H A - 1 0 0 . S a m p l e s w e r e d i s s o l v e d i n c a r b o n t e t r a c h l o r i d e to 20% s o l u t i o n b y vo lume unless o t h e r w i s e s ta ted. T e t r a m e t h y l s i l a n e w a s used as i n -t e r n a l s t a n d a r d . The v a p o r phase c h r o m a t o g r a p h y unit used w a s an A e r o g r a p h M o d e l A - 9 0 - P equipped w i t h a t h e r m a l c o n d u c t i v i t y detec tor . 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 D r . A . B e r n -h a r d t and b y M r s . C . J e n k i n s and M r . P . B o r d a of this depar tment . - 77 -P r e p a r a t i o n of m e t h y l 1, 2, 2 - t r i m e t h y l - 1 - c y c l o p r o p a n e c a r b o x y l a t e (32) A c e t o n e a z i n e : 75 g (1.5 m o l e s ) of h y d r a z i n e hydrate (99-100%) w a s added s l o w l y to 176 g (3 m o l e s ) of acetone at 0 ° . The m i x t u r e w a s then heated i n a s t e a m bath f o r 5 h r s , c o o l e d to r o o m t e m p e r a t u r e , 50 g of anhydrous p o t a s s i u m carbonate w a s added to a i d s e p a r a t i o n of w a t e r . T h i s t r e a t m e n t w a s repeated w i t h 20 g p o r t i o n s u n t i l the p r o d u c t w a s d r y . The o r g a n i c f r a c t i o n w a s f r a c t i o n a l l y d i s t i l l e d to g ive 135 g (80%) of a c o l o r l e s s l i q u i d , b. p . 1 3 2 - 3 ° , n ^ 5 1.4514 ( l i t . (85), b . p. o 20 129-32 , n D 1.4533). A c e t o n e h y d r a z o n e : a m i x t u r e of 135 g (1.2 m o l e s ) of acetone az ine and 60 g (1.2 m o l e s ) of h y d r a z i n e hydra te w a s heated at 110° f o r 17 h r s . It w a s then r e p e a t e d l y t r e a t e d w i t h 20 g p o r t i o n s of anhydrous p o t a s s i u m carbonate i rnt i l d r y . F r a c t i o n a l d i s t i l l a t i o n gave 145 g (84%) of a c o l o r l e s s l i q u i d , b . p. 1 2 0 - 2 ° ( l i t . (86), b . p. 1 1 5 - 2 0 ° ) . 3, 5, 5 - T r i m e t h y l - 3 - c a r b o m e t h o x y — A * - P y r a z o l i n e (50): a m i x -ture of 58 g (0.25 mole) of s i l v e r oxide and 300 m l of anhydrous ether w a s c o o l e d to - 6 0 ° , to this w e r e added s i m u l t a n e o u s l y 18 g (0.25 mole) of acetone h y d r a z o n e and 15 g (0.15 mole) of m e t h y l m e t h a c r y l a t e w i t h s t i r r i n g o v e r a p e r i o d of 10 minutes (2 -d iazopropane p r e p a r e d i n s i t u (47)). . The r e s u l t i n g m i x t u r e w a s f i r s t a l l o w e d to w a r m up to - 2 5 ° and was kept s t i r r i n g at that t e m p e r a t u r e f o r 60 m i n u t e s , then w a r m e d to r o o m t e m p e r a t u r e . The b l a c k p r e c i p i t a t e was f i l t e r e d , the ether f l a s h evapora ted . The r e s i d u e w a s f r a c t i o n a l l y d i s t i l l e d to g ive 15 g of 5 0 , - 78 -b . p . 5 5 - 6 ° at 0.1 m m . A n a l . C a l c d . f o r C ^ H ^ O ^ N : C , 56.47; H , 8.23; N , 16.47. F o u n d : C , 56.30; H , 8.13; N , 16.35. The N . M . R . s p e c t r u m of 50 shows the f o l l o w i n g peaks , the C - 5 m e t h y l s at 8.64 X and 8.60 X (both s ingle t ) , the C - 4 hydrogens at 8.79 T and 8.03 X (both doublet , J ^ 1 3 . 1 c . p . s . ) , the C - 3 m e t h y l at 8.46 T (singlet) and the e s t e r m e t h y l at 6.27 'T ( s ingle t ) . L i q u i d phase p y r o l y s i s of 12.5 g of 3, 5, 5 - t r i m e t h y l - 3 - c a r b o -m e t h o x y - £\ - p y r a z o l i n e (50) at 9 0 - 1 0 0 ° gave 9.5 g (91%) of a c o l o r l e s s l i q u i d b o i l i n g up to 1 6 5 ° . V a p o r phase c h r o m a t o g r a p h i c s e p a r a t i o n u s i n g a 20' x 3 / 8 " d inonylphthalate c o l u m n at 15 8° w i t h h e l i u m f low rate of 85 m l per m i n gave two components , A and B i n the ra t io of 83.8% to 16.2%, r e t e n t i o n t i m e of 14.6 and 22.3 m i n r e s p e c t i v e l y . 2 5 Component A : b . p . 1 4 8 . 5 ° , n 1.4280, w a s a s s i g n e d the s t r u c -ture of m e t h y l 1, 2, 2 - t r i m e t h y l - 1 - c y c l o p r o p a n e c a r b o x y l a t e (32) on the b a s i s of i t s N . M . R . s p e c t r u m (20% b y v o l u m e i n benzene) w h i c h shows three s ingle ts at 9.01 X, 8.87 X and 8.74 ^ f o r the three r i n g m e t h y l s , another s i n g l e t at 6.57 X f o r the es ter m e t h y l , two doublets at 9.74 X. and 8.58 ' C (J —4.6 c .p .s . ) f o r the A B s y s t e m f o r the C - 3 h y d r o g e n s . g e m When c a r b o n t e t r a c h l o r i d e w a s used as so lvent f o r the N . M . R . s p e c t r u m , the low f i e l d doublet a p p e a r e d h idden under the low f i e l d s i n g l e t w h i c h now appeared at 8.71 /l. A n a l . C a l c d . f o r C r l ^ i C , 67.57; H , 9-93. F o u n d : C , 67.69; K , 9.38. - 79 -A . s p l i t t i n g s of methyls on C - 4 and hydrogen on C-,4 B . the m u l t i p l e t due to the h y d r o g e n on C - 4 i s r e d u c e d to a doublet w i t h some f u r t h e r long range s p l i t t i n g when the m e t h y l s on C - 4 a r e i r r a d i a t e d ! F I G U R E 15 - Double resonance N . M . R. s p e c t r u m of 43 - 80 -C o m p o n e n t B : b . p. 1 6 4 . 5 ° , 1.4366 ( l i t . (90), b . p . 4 9 - 5 0 u at 10 m m , n 1.4384), i t showed I. R . and N . M . R . bands c h a r a c t e r i s -t i c of m e t h y l t r a n s - 2 , 4 - d i m e t h y l - 2 - p e n t e n o a t e (43). The I. R . s p e c t r u m shows bands at 1714 c m " * and 1649 c m " * for the conjugated c a r b o n y l and double bond s t r e t c h i n g v i b r a t i o n s r e s p e c t i v e l y . The N . M . R . s p e c -t r u m shows peaks at 8.98 X (doublet, c .p .s . ) f o r the C - 4 m e t h y l s , 8.20 X (doublet, ^ 3— 1 . 4 c .p .s . ) f o r the C - 2 m e t h y l , 6.33^C (singlet) f o r the e s t e r m e t h y l , 3.51 X (2 q u a r t e t s , J £ii9,6 c . p . s . , 1 > ^ J-j_ 3—1 . 4 c . p . s . ) f o r the o l e f i n i c h y d r o g e n and 7.36 'X (mult iplet ) f o r the C - 4 h y d r o g e n . The m u l t i p l i c i t y of the 7.36 X m u l t i p l e t w a s r e d u c e d w h e n the 8.98 "iT doublet w a s i r r a d i a t e d e m p l o y i n g the double resonance technique (87) at 100 M c ( F i g u r e 15). A n a l . C a l c d . f o r C H O : C , 67.57; H , 9.93. F o u n d : C , 67.85; H , 9.71. P r e p a r a t i o n of m e t h y l 2, 2 - d i m e t h y l - 1 - c y c l o p r o p a n e c a r b o x y l a t e (35) 1 2 5, 5 - D i m e t h y l - 3 - c a r b o m e t h o x y - A - p y r a z o l i n e (53) and A _ p y r a z o l i n e (54): 116 g (0.5 mole) of s i l v e r oxide i n 500 m l of anhydrous ether w a s r e a c t e d w i t h 36 g (0.5 mole) of acetone h y d r a z o n e and 43 g (0.5 mole) of m e t h y l a c r y l a t e as d e s c r i b e d i n the p r e p a r a t i o n of 5 0 above except that the m i x t u r e w a s kept at - 2 5 ° f o r 30 m i n . F r a c t i o n a l d i s t i l l a t i o n gave 31 g of a c o l o r l e s s l i q u i d , b . p. 8 5 - 9 7 ° at 0.1 m m , 1 2 w h i c h wa3 shown b y N . M . R . to be a m i x t u r e of the A - and A _ o pyrazo lones . Subsequent d i s t i l l a t i o n gave a f r a c t i o n , b . p . 96-7 at 0.1 mrm, - 81 -of pure A - p y r a z o l i n e (54). The N . M . R . s p e c t r u m of 54 shows the C - 5 m e t h y l s at 8.72 "X ( s inglet ) , the C - 4 hydrogens at 7.36 X (s inglet) , the e s t e r m e t h y l at 6.27 X (singlet) and the N - l h y d r o g e n at 3.16 X (broad). 2 T h r o u g h a c o m p a r i s o n of the s p e c t r u m of the pure A - p y r a z o l i n e (54) 1 2 and that of the A _ and A - p y r a z o l i n e m i x t u r e , the f o l l o w i n g peaks w e r e a s s i g n e d to the A * - p y r a z o l i n e (53), the C - 5 m e t h y l s at 8.33 X and 8.15 T (both s ing le t ) , the C - 4 hydrogens at 7.49 X and 6.71 X (both m u l t i p l e t s ) , the e s t e r m e t h y l at 6.37 X (s inglet) and the C - 3 h y d r o g e n at 5.41 X (broad). P y r o l y s i s of 31 g of the m i x e d . : p y r a z o l i n e s (53 and 54) at 1 0 0 - 1 7 0 ° y i e l d e d 24 g (94%) of a c o l o r l e s s l i q u i d b o i l i n g up to 1 5 0 ° . T h i s w a s s e p a r a t e d b y V . P . C . u s i n g a 2 0 ' x 3 / 8 " dinonylphthalate c o l u m n at 165° w i t h h e l i u m f l o w rate of 85 m l p e r m i n to g ive components C and D i n the ra t io of 3:7 w i t h r e t e n t i o n t i m e of 11.0 and 16.2 m i n r e s p e c t i v e l y . C o m p o n e n t C : this w a s found to be a m i x t u r e of m e t h y l 2, 2 - d i -m e t h y l - 1 - c y c l o p r o p a n e c a r b o x y l a t e (35) and m e t h y l c i s - 4 - m e t h y l - 2 - p e n -tenoate (44) i n the ra t io of a p p r o x i m a t e l y 85:15 (or 23% and 4% r e s p e c -t i v e l y of the to ta l p r o d u c t f r o m p y r o l y s i s ) as i n d i c a t e d b y N . M . R . a n a l y -s i s . 35_ showed N . M . R . peaks at 8.86 T and 8.81 t (both s ingle t ) f o r the m e t h y l s on C - 2 , 6.37 T (s inglet) f o r the e s t e r m e t h y l , 8.5 0 X^ (pair of doublet) f o r the C - l h y d r o g e n , 9.0 X (pair of doublet , 100 M c i n b e n -zene) f o r the C - 3 h y d r o g e n t rans to the C - l h y d r o g e n and 9.21 X" ( P a i r of. doublet) f o r the C - 3 h y d r o g e n c i s to the C - l h y d r o g e n . The C - l and C - 2 hydrogens f o r m an A B X coupl ing s y s t e m w i t h J £ ^ 4 . 0 c . p . s . , - 82 -J . £ ^ 8 . 1 c . p . s . and J 5.1 c . p . s . M e t h y l c i s - 4 - m e t h y l - 2 - p e n -CIS L"I*CLX1S tenoate (44) showed N . M . R . peaks at 8.99 'T (doublet, J £ i 6 . 6 c . p . s . ) f o r the C - 4 m e t h y l s , 6.36 X (singlet) for the es ter m e t h y l , 4.43 (doublet, J . — 11.4 c . p . s . ) f o r the C - 2 o l e f i n i c h y d r o g e n and 4.03 cT CIS-(2 double ts , J c i g ££.11.4 c . p . s . , J ^ 2 — 9.2 c . p . s . ) f o r the C - 3 o l e f i n i c h y d r o g e n . A t t e m p t s to separate 35 and 44 w e r e u n s u c c e s s f u l . * C o m p o n e n t D : b . p . 1 5 0 ° , n ^ 1.4298, w a s c h a r a c t e r i z e d b y N . M . R . and I. R . s p e c t r a l anay lses to be m e t h y l t r a n s - 4 - m e t h y l - 2 -pentenoate (45). T h r e e I. R . bands at 1723 c m " 1 , 1657 c m " 1 and 990 c m " 1 a r e c o n s i s t e n t w i t h the s t r u c t u r e a s s i g n e d . Its N . M . R . s p e c t r u m shows peaks at 8.91 ' T (doublet, J—6.7 c . p . s . ) f o r the C - 4 m e t h y l s , 6.34 X (s inglet) f o r the e s t e r m e t h y l , 4.32 ^ (2 doublets , J £115.8 c . p . s . , 3 — c . p . s . ) f o r the C - 2 o l e f i n i c h y d r o g e n , 3.14 X (2 d o u -b l e t s , J , d 15.8 c . p . s . , J . _ £1 6.5 c . p . s . ) f o r the C - 3 o l e f i n i c h y d r o -' t r a n s ^ 1 , 2 ' gen and 7.54 X (mul t ip le t ) f o r the C - 4 h y d r o g e n . A n a l . C a l c d . forC^'^: C , 65.49; H , 9.45. F o u n d : C , 65.39; H , 9.44. P r e p a r a t i o n of c i s - and t r a n s - 1 , 2 - d i m e t h y l - 1 - c y a n o c y c l o p r o p a n e (41 &40) 3, 5 - D i m e t h y l - 3 - c y a n o - / \ - p y r a z o l i n e (55): 12 g of m e t h a c r y -l o n i t r i l e w a s added i n 5 m i n to an e t h e r e a l s o l u t i o n of diazoethane ( f r o m 40 g of N - n i t r o s o e t h y l u r e a ) (88) at 0° and the r e s u l t i n g so lut ion was lef t s t i r r i n g f o r 30 m i n . F l a s h e v a p o r a t i o n of the ether gave 20 g of crude 55. A n a l . C a l c d . f o r C ? H 1 ? 0 2 ( - m i x t u r e of 35 and 44): C , 65 .49 ; H , 9.45. F o u n d : C , 65.37; H , 9.62. - 83 -The N . . M . R . s p e c t r u m ( F i g u r e 1, p. 21) of the c r u d e 55 showed it to be a m i x t u r e of the c i s and trans i s o m e r s (the C - 3 m e t h y l and the C - 5 methyl ) w i t h peaks s i m i l a r to those of an analogous m i x t u r e of c i s - and t r a n s -3, 5 - d i m e t h y l - 3 - c a r b o m e t h o x y - £A-pyrazoline (3). T e n g r a m s of the c rude 55 w a s p y r o l y s e d at a t e m p e r a t u r e of 100° and s e p a r a t i o n by V . P . C . u s i n g a 2 0 ' x 3 / 8 " dinonylphthalate c o l u m n at 145° w i t h h e l i u m f low rate of 85 m l per m i n gave three components , E , F and G i n the r a t i o of 52.6%, 44.4% and 3.0% w i t h re tent ion times of 13.6, 17.5 and 20.0 m i n r e s p e c t i v e l y . o 2 6 Component E : b . p . 137.5 , n 1.4179, i t w a s a s s i g n e d the s t r u c t u r e of t rans - 1 , 2 - d i m e t h y l - 1 - c y a n o c y c l o p r o p a n e (40). It showed an I. R . ( P e r k i n - E l m e r M o d e l 137) band at 2242 c m " ^ c h a r a c t e r i s t i c of the C s N s t r e t c h i n g v i b r a t i o n . The N . M . R . s p e c t r u m of 40 showed the C - l m e t h y l at 8.65 X ( s inglet ) , the C - 2 m e t h y l at 8.70 'b; (doublet, J£d5.(> c . p . s . ) and the three r i n g hydrogens i n the r e g i o n 8.80 X to 9.30 >T ( m u l t i p l e t ) . A n a l . C a l c d . for C ^ N : C , 75.74; H , 9.54; N , 14.72. F o u n d : C , 75.82; H , 9.67; N , 14.92. o 26 Component F : b . p . 149 , n ^ 1.4238, i t w a s a s s i g n e d the s t r u c t u r e c i s - 1, 2 - d i m e t h y l - 1 - c y a n o c y c l o p r o p a n e (4.1). Its N . M . R . s p e c -t r u m shows the C - l m e t h y l at 8.69 X ( 3 m g h e t ) , the C - 2 m e t h y l at 8.75 X (doublet, J jb8.5 c .p . s . ) , one of the r i n g hydrogens at 9.60 'C' (mult iplet ) and the r e m a i n i n g hydrogens at the r e g i o n 8.5 0 ^ to 9.00 ?J (mult iplet ) w h i c h is under the 8.69 X a*1^ 8.75 ^ s ignals and thus not r e s o l v e d . - -84 -A n a l . C a l c d . f o r C ^ H ^ N : C , 75.74; H , 9.54; N , 14.72. F o u n d : C , 75.72; H , 9.80; N , 14.82. 2 6 Component G : b . p. 155° , n ^ 1.4326, it w a s a s s i g n e d the s t r u c t u r e of 2 - m e t h y l - 2 - p e n t e n o n i t r i l e (57).. Its I. R . s p e c t r u m ( P e r k i n E l m e r M o d e l 137) shows C H N s t r e t c h i n g v i b r a t i o n at 2208 c m " . The N . M . R.- s p e c t r u m of 57 shows peaks at 8.95 X ( t r ip le t , J r V 7 . 4 c . p . s . ) f o r the C - 4 m e t h y l , 8.14 X (broad) f o r the C - 2 m e t h y l , 7.80 X (quintet) for the C - 4 methylene hydrogens and 3.74 (mult iplet ) f o r the C - 3 o l e f i n i c h y d r o g e n . A n a l . C a l c d . f o r C ^ H ^ N : C , 75.74; H , 9.54; N , 14.72. F o u n d : C , 75.56; H , 9.71; N , 14.58. P r e p a r a t i o n of m e t h y l c i s - and t rans - 2 , 4 - d i m e t h y l - 2 - p e n t e n o a t e (42 &43) ( C ) - m e t h y l - ( P ) - d i e t h y l - . ^ - p h o s p h o n o p r o p i o n a t e : a m i x t u r e of 66 g (0..4 mole) of t r i e t h y l p h o s p h i t e and 34 g (0.2 mole) of m e t h y l o{-b r o m o p r o p i o n a t e w a s heated i n a 5 00 m l two n e c k e d round bot tom f l a s k equipped w i t h a t h e r m o m e t e r and a condenser w h i c h w a s connected to a d r y i ce -ace tone t r a p . E t h y l b r o m i d e began to f o r m and condensed at the t r a p when the r e a c t i o n t e m p e r a t u r e r e a c h e d 120° and c e a s e d at 1 7 0 ° . The r e s u l t i n g s o l u t i o n w a s d i s t i l l e d to give 42 g (93%) of a c o l o r l e s s l i q u i d , b . p . 6 2 - 5 ° at 0.. 15 m m . Its N . M . R . s p e c t r u m shows the C - 2 m e t h y l at 8.68 X (pair of doublets , 1 ^ 7 . 2 c . p . s . , ^ 17.8 c .p .s . ) , the C - 2 h y d r o g e n at 6.94 (pair of quar te ts , J c i 7 . 2 c . p . s . , 23.5 c . p . s . ), the ( C ) - e s t e r m e t h y l at 6.31 X (s inglet) , the m e t h y l on the ( P ) - e t h y l at - 85 -8.72 'b ( t r ip le t , Jc^-7.1 c . p . s . ) and the methylene hydrogens of the ( P ) -ethyi at 5.89 T. (pair of quar te t s , J i i 7 . 1 c . p . s . , J ^'2h 8.5 c .p .s . ) Two h u n d r e d m i l l i l i t r e s of g lyme ( d i s t i l l e d f r o m s o d i u m h y d r i d e ) i n a 1 - l i t e r three n e c k e d r o u n d bot tom f l a s k equipped w i t h a d r o p p i n g funne l , a s t i r r e r and a t h e r m o m e t e r was coo led to 0 , 11 g (0.19 mole) of s o d i u m h y d r i d e (49% d i s p e r s i o n i n o i l ) was added and s t i r r e d . To o this s u s p e n s i o n m a i n t a i n e d at 15-20 w a s added d r o p w i s e w i t h s t i r r i n g i n one h r 42.5 g (0.19 mole) of ( C ) - m e t h y I - ( P ) - d i e t h y l - o ( - p h o s p h o n o p r o -pionate , a f ter the a d d i t i o n , i t w a s kept s t i r r i n g f o r 1 h r at 15° f o l l o w e d b y 5 m i n at 3 5 ° , then i t w a s c o o l e d to 15° . To this was added i n 15 m i n 14.5 g (0.19 mole) of i s o b u t y r a l d e h y d e w i t h v i g o r o u s s t i r r i n g . The r e -s u l t i n g m i x t u r e was heated to r e f l u x for 20 m i n , c o o l e d to r o o m t e m p e r -a ture , d i l u t e d w i t h 300 g of i c e , e x t r a c t e d w i t h 5 p o r t i o n s of 100 m l of e ther . The c o m b i n e d e t h e r e a l s o l u t i o n w a s w a s h e d three t i m e s w i t h 250 m l of w a t e r , d r i e d w i t h anhydrous s o d i u m sul fa te . F l a s h e v a p o r a t i o n of e ther gave 23 g (83%) of a c o l o r l e s s l i q u i d w h i c h when a n a l y z e d b y V . P . C . us ing a 1 0 ' x 1/4" dinonylphthalate c o l u m n at 166° w i t h h e l i u m f low of 35 m l per rn in gave 55.8% m e t h y l c i s - 2 , 4 - d i m e t h y l - 2 - p e n t e n o a t e (42), 16.2% e thyl es ter of 42, 21.6% of m e t h y l t r a n s - 2 , 4 - d i m e t h y l - 2 - p e n t e n o -are (43) and 6.4% e thyl e s t e r of 43 w i t h re tent ion t i m e s 15.5, 21.2, 24.2 and 32.6 m i n r e s p e c t i v e l y . The e thy l es ters can be c o n v e r t e d to t h e i r r e s p e c t i v e m e t h y l e s t e r s b y the f o l l o w i n g p r o c e d u r e . Three and a hal f g r a m s of the above p r o d u c t i n IQ m l of 30% p o t a s s i u m h y d r o x i d e s o l u t i o n - 86 -w a s heated w i t h constant s t i r r i n g u n t i l o n l y one l a y e r w a s r e s u l t e d (1 hr) , e v a p o r a t e d to d r y n e s s on a s t e a m bath, d i l u t e d w i t h 20 m l of w a t e r , c o o l -o ed to 0 , a c i d i f i e d w i t h concentra ted h y d r o c h l o r i c a c i d on Congo R e d . E x -t r a c t e d 3 t i m e s w i t h 25 m l p o r t i o n s of e ther , the c o m b i n e d e x t r a c t w a s d r i e d w i t h anhydrous s o d i u m sul fa te , and t rea ted w i t h diazomethane i n e ther , f l a s h e v a p o r a t i o n gave 3. 4 g (99%) of a c o l o r l e s s l i q u i d w h i c h c o n s i s t e d of 71.2% of 42 and 28.8% of 43. o 25 M e t h y l c i s - 2 , 4 - d i m e t h y l - 2 - p e n t e n o a t e (42): b . p. 149.5 , 1.4308 ( l i t . (90), b . p . 5 8 - 9 ° at 23 m m , n ^ ° 1.4328). It showed I. R . bands at 1772 c m * and 1646 c m * f o r the conjugated c a r b o n y l and d o u -b le bond s t r e t c h i n g v i b r a t i o n s r e s p e c t i v e l y . The N . M . R . s p e c t r u m shows peaks at 9.04 T (doublet, 3^-i>.l c .p .s . ) f o r the C - 4 m e t h y l s , 8.18 X (doublet, J1 3 Ar-1.4 c .p .s . ) f o r the C - 2 m e t h y l , 6.32 'T (singlet) f o r thees ter m e t h y l , 4.38 X (pair of quar te t s , J ^ 2 ~ 9.6 c . p . s . , 3 — 1.4 c . p . s . ) f o r the C - 3 o l e f i n i c h y d r o g e n and 6.75 *T (mult ip le t ) f o r the C - 4 h y d r o g e n . A n a l . C a l c d for C g H 1 4 0 : C , 67.57; H , 9.93. F o u n d : C , 67.38; H , 10.00. • M e t h y l t r a n s - 2 , 4 - d i m e t h y l - 2 - p e n t e n o a t e (43): the p h y s i c a l data, e l e m e n t a l a n a l y s i s and s p e c t r a l a ss ignments ha vs been g iven e a r l i e r (p. 80) P r e p a r a t i o n of m e t h y l c i s - and t r a n s - 4 - m e t h y l - 2 - p e n t e n o a t e (44 and 4_5) T r i m e t h y l phosphonoacetate : a m i x t u r e of 77 g (0.5 mole) of bromoace ta te and 87 g (0.7 mole) of t r i m e t h y l phosphite was heated f r o m - 87 -80 to loO as d e s c r i b e d e a r l i e r f o r the p r e p a r a t i o n of ( C ) - m e t h y l - ( P ) -d i e t h y l - X ~ p h o s p h o n o p r o p i o n a t e . F r a c t i o n a l d i s t i l l a t i o n y i e l d e d 73 g (80%) of a c o l o r l e s s l i q u i d , b . p. 8 5 - 6 ° at 0.08 m m . A n a l . C a l c d for C 5 K n 0 5 P : C , 32,97; H , 6.09. F o u n d ; C , 32.63; IT, 6.37. The N . M . R . s p e c t r u m o£ t r i m e t h y l phosphonoacetate shows the ( P ) - e s t e r m e t h y l s at 6.25 "T (doublet, p^x .11 .1 c . p . s . ) , the m e t h y l -ene hydrogens at 7.07 "t (doublet, J .hi 21.7 c . p . s . ) and the ( C ) - e s t e r H - P m e t h y l at 6.28 ' X (s inglet) . The l a t t e r showed a doublet (J - o — 0-6 c . p . s . ) on expanded 100 M c N . M . R . s p e c t r u m . T w e n t y - t w o g r a m s (0.3 mole) of i s o b u t y r a l d e h y d e w a s r e a c t e d w i t h 54.6 g (0.3 mole) of t r i m e t h y l phosphonoacetate , 14.4 g (0.3 mole ) of s o d i u m h y d r i d e i n 300 m l of g l y m e a c c o r d i n g to the p r o c e d u r e d e s c r i b e d above f o r the p r e p a r a t i o n of 42 and 43 w i t h m i n o r change. A f t e r the a d -d i t i o n of i s o b u t y r a l d e h y d e , the m i x t u r e w a s kept s t i r r i n g f o r 20 m i n at 2 0 ° i n s t e a d of under r e f l u x . The y i e l d was 17.6 g (46%) c o n s i s t i n g of 30.3% of m e t h y l c i s - 4 - m e t h y l - 2 - p e n t e n o a t e (44) and 69.2% of m e t h y l t r a n s - 4 - m e t h y l - 2 - p e n t e n o a t e (45) as shown b y V . P . C . The m i x t u r e o was d i s t i l l e d w i t h a sp inning band c o l u m n to give 5.2 g 44, b . p. 138-40 and 9.2 g 45, b . p. £48-5 0 ° . o 22 M e t h y l cis_-4-methyl-2-pentenoate (44): p . p . 140 , n_^ 1.4225. It showed I. R . band3 at 1723 c m - 1 and 1650 c m " 1 and 1417 c m " 1 . The N . M . R . s p e c t r a l data have been r e p a r t e d e a r l i e r i n this thes is (p. 82). - 83 -A n a l . C a c l d . f o r C H ^ O . , : C , 65.59; H , 9.44. F o u n d : C , 65.60; H, 9 .56 . M e t h y l t r a n s - 4 - m e t h y l - 2 -pentenoate (45): a l l p h y s i c a l data, e l e m e n t a l a n a l y s i s and s p e c t r a l database been p r e s e n t e d e a r l i e r i n this t h e s i s . (p. 82 }. A s i m i l a r r e a c t i o n u s i n g ( C ) - m e t h y l - ( P ) - d i e t h y l p h o s p h o n o a c e t a t e , whose p r e p a r a t i o n i s . g i v e n b e l o w , i n 0.1 m o l e s c a l e y i e l d e d 7 g (5 3%) of a m i x t u r e c o n s i s t i n g of 4% of c i s i s o m e r s (44 and e thy l e s t e r of 44) and 96% of t rans i s o m e r s (45 and e thyl e s te r of 45). The ra t io of m e t h y l e s t e r s to e thyl e s t e r s w a s a p p r o x i m a t e l y 32:68. ( C ) - m e t h y l ~ ( P ) - d i -ethylphos phono acetate w a s p r e p a r e d a c c o r d i n g to the method u s e d f o r the p r e p a r a t i o n of t r i m e t h y l phosphonoacetate . A m i x t u r e of 5 1 g (0.33 mole) of m e t h y l b r o m o a c e t a t e and 85 g (0.5 mole) of t r i e t h y l phosphite w a s h e a t -ed f r o m 9 5 - 1 7 0 ° and w o r k e d up,.to y i e l d 61 g (88%) of ( C ) - m e t h y l - ( P ) -die thylphosphonoacetate , b . p . 7 1 - 3 ° at 0.1 m m (89). Its N . M . R . s p e c t r u m shows peaks at 6.30 '"C (s inglet) f o r the ( C ) - e s t e r m e t h y l , 6.96 (dou-ble t , J ^si.21.9 c . p . s . ) f o r the C - 2 methylene h y d r o g e n s , 5.88 X (pair . H - P of q u a r t e t s , J -^7 .1 c . p . s . , J £^.8.4 c .p .s . ) f o r the methylene hydrogens H - P of the e s t e r e thy l and 8.71 'X ( t r ip le t , J ^ -7 .1 c .p .s . ) f o r the m e t h y l of the es ter e t h y l . P r e p a r a t i o n of m e t h y l c i s - and trans - 2 - m e t h y l - 2 - p e n t e n o a t e (46 and 47) this was T r i m e t h y l ^ - p h o s p h o n o p r o p i o n a t e ^ p r e p a r e d a c c o r d i n g to the method for the p r e p a r a t i o n of t r i m e t h y l phosphonoacetate. T h u s , f r o m - 89 -75 g (0.6 mole) of t r i m e t h y l phosphite and 67 g (0.4 mole ) of m e t h y l b r o m o p r o p i o n a t e at r e a c t i o n t e m p e r a t u r e 9 5 - 1 5 0 ° , 25 g (53% b a s e d on the m e t h y l c. -bromopropionate used) of t r i m e t h y l • ck -pho sphonopropionate , b . p . 8 2 - 4 ° at 0.1 m m , w a s obta ined. It showed N . M . R . peaks at 8.65 XT (pair of double ts , J —7.2 c . p . s . , J c ^ l 7 . 9 c .p .s . ) f o r the C - 3 m e t h y l , 7.02 r C (mult iple t ) f o r the C - 2 h y d r o g e n , 6.29 '"^  (singlet) f o r the (C}~ e s t e r m e t h y l and 6.28 r'( (doublet, J p — 11.0 c .p . s . ) f o r the ( P ) - e s t e r m e t h y l s . A c c o r d i n g to the p r o c e d u r e d e s c r i b e d above f o r the p r e p a r a t i o n 7.5 g (0.125 mole) of propiona idehyde and of 44 and 45, 24.5 g (0.125 mole) of t r i m e t h y l o{-phosphonopropionate,J 6 g (0.125 mole ) of s o d i u m h y d r i d e i n 150 m l of glyme> gave 5 g (56%) of ^o c o l o r l e s s l i q u i d , b . p . 130-55 . It was a n a l y s e d b y V . P . C . us ing a 10' b y 1/4" d inonylphthala te c o l u m n at 170° , w i t h h e l i u m f low of 35 m l per m i n to g ive 38% of m e t h y l c i s - 2 - m e t h y l - 2 - p e n t e n o a t e (46) and 62% of m e t h y l t r a n s - 2 - m e thy l -2 -pentenoate (47) . B o t h 46 and 47 had been c h a r a c t e r i z e d b y t h e i r N . M . R . and I. R . s p e c t r a l a n a l y s e s . T h e y w e r e i d e n t i c a l to those r e p o r t e d e a r l i e r (3). A s e c o n d p r e p a r a t i o n U 3 i n g ( C ) - m e t h y l - ( P ) - d i e t h y l - o C ~ P n o s p h o n o -propionate y i e l d e d 12 g (73%) of a mbcture c o n s i s t i n g of 13% c i s e s t e r s (46 and e thy l e s te r of 46) and 87% of t rans e s t e r s (47_ and ethyl e s te r of 47). The ra t io of m e t h y l e s t e r s to e thyl e s t e r s was 72:23. P r e p a r a t i o n of c i s - and t rans -2 -pentenoate (48 and 49) A c c o r d i n g to the p r o c e d u r e d e s c r i b e d above for the p r e p a r a t i o n - 90 -of 44_ and 45_, 8,7 g (0.15 mole ) of p r o p i o n a l d e h y d e , 31.5 g (0.15 mole) of ( C ) - m e t h y l - ( P ) - d i e t h y l - p h o s p h o n o a c e t a t e and 7.2 g (0.15 mole) of s o d i u m h y d r i d e i n 150 m l of g l y m e gave 6.5 g (43%) l i q u i d . V a p o r phase o c h r o m a t o g r a p h i c a n a l y s i s ( l O ' x l / 4 " dinonylphthalate c o l u m n at 168 , h i l i u m f low of 35 m l per min) of the p r o d u c t gave 4% of c i s e s t e r s (48 and e t h y l e s t e r of 48) and 96% of t rans e s t e r s (49 and e thy l e s t e r of 49). The ra t io of m e t h y l e s t e r s to e thyl e s t e r s w a s 79:21. Both 48 and 49 h a d been c h a r a c t e r i z e d b y c o m p a r i n g t h e i r I. R . and N . M . R . spectra to those r e p o r t e d p r e v i o u s l y (2). T h e r m a l r e a r r a n g e m e n t of m e t h y l 1,2,2- t r i m e t h y l -1 - c y c l o p r o p a n e -c a r b o x y l a t e (32) at 2 80° A s a m p l e of 5 00 jji of 32 i n a s e a l e d N . M . R . tube w a s heated at 2 8 3 ° f o r 10 h r . The p r o d u c t w a s a n a l y z e d b y V . P . C . ( l O ' x l / 4 " d i -decylphthala te c o l u m n at 15 0° w i t h h e l i u m f l o w rate of 40 m l per min) to g ive the s t a r t i n g m a t e r i a l ( less than 2%) and m e t h y l 2, 4 - d i m e t h y l - 4 -pentenoate (67) at 12.2 and 13.8 m i n r e s p e c t i v e l y . o 24 M e t h y l 2 , 4 - d i m e t h y l - 4 - p e n t e n o a t e (67): b . p. 155 , l.'422S o 20 ( l i t . (91), b . p. 51 at 12 m m , n ^ 1.4270). It showed N . M . R . peaks at 8.91 :T (doublet, J—' 6.5 c .p .s . ) f o r the C - 2 m e t h y l , 8.31 •'"( (broad) f o r the C - 4 m e t h y l , 6.41 T (singlet) for the es ter m e t h y l , 5.31 T (broad) f o r the C - 5 t e r m i n a l methylene hydrogens and at the r e g i o n of 7.20 - l to 8.10 '"C (mult iplet ) f o r the C - 2 and C - 3 h y d r o g e n s . A n a l . C a l c d . f o r C g H ^ O ^ C , 67.57; PI, 9-93. F o u n d : C , 67.42 - 91 -T h e r m a l r e a r r a n g e m e n t of m e t h y l t rans _1 - m e t h y l - 2 - e t h y l - 1 - c y c l o p r o -p a n e c a r b o x y l a t e (33) at 280° A s a m p l e of 0.5 m l of 33 i n a sea led N . M . R. tube was heated at 2 8 0 ° f o r 18 h r . A n a l y s i s b y V . P . C . us ing a Z C ' x l / 4 " diethylene g l y c o l succ inate c o l u m n at 15 3° w i t h h e l i u m f low rate of 35 m l per m i n gave a trace amount of 33, 17.5% of m e t h y l c i s - 2 - m e t h y l - 4 - h e x e n o a t e (68) and 82.5% of m e t h y l t r a n s - 2 - m e t h y l - 4 - h e x e n o a t e (69) w i t h r e t e n t i o n t i m e s of 18.5, 23.1 and 26.1 m i n r e s p e c t i v e l y . 2 6 M e t h y l ci3 - 2 - m e t h y l - 4 - h e x e n o a t e (68): b . p. 164.5 , n 1.4261. It showed a c a r b o n y l band at 1737 c m " * . The N . M . R . s p e c t r u m shows the C - 2 m e t h y l at 8.88 K. (doublet, c . p . s . ) , the C - 5 m e t h y l at 8.39 ''C (doublet, J ^ 5 . 7 c . p . s . ) , the es ter m e t h y l at 6.40 T (s inglet ) , the C - 2 and C - 3 hydrogens at 7.35 T to 8.05 T (mult iple t ) and the o l e f i n i c hydrogens at 4.25 ""C to 4.95 "T (mul t ip le t ) . A n a l . C a l c d . f o r C g H ^ O ^ C , 67.57; H , 9-93. F o u n d : C , 67.33; H , 9.97. o 26 M e t h y l t r a n s - 2 - m e t h y l - 4 - h e x e n o a t e (69): b . p. 161 , n ^ 1.4225 It showed two I. R . bands at 1736 c m " * and 973 c m " * due to the c a r b o n y l and C - H o u t - o f - p l a n e s t r e t c h i n g v i b r a t i o n s r e s p e c t i v e l y . . The N . M . R. s p e c t r u m shows the C - 2 m e t h y l at 8.96 ''C (doublet, Jc=l6.5 c . p . s . ) , the C - 5 m e t h y l at 8.36 -T (doublet, J l i . 4 . 7 c .p .s . ) the e s t e r m e t h y l at 6.41 "r (s inglet) , the C - 2 and C - 3 hydrogens at 7.50 ^ to 8.10 'T/ (mult iplet ) and the o l e f i n i c hydrogens at 4. 50 T to 5.00 'T, (mul t ip le t ) . - 92 -A n a l . C a l c d . f o r C H O : C , 67.57; H , 9.93. F o u n d : C , 67.36; 8 12 2 K , 10.00. T h e r m a l r e a r r a n g e m e n t of m e t h y l 2, 2 - d i m e thy l - 1 - c y c l o p r o p a n e -c a r b o x y l a t e (35) at 25 8° A s a m p l e (0.5 m l ) c o n s i s t i n g of 85% of 35 and 15% of m e t h y l c i s - 4 - m e t h y l - 2 - p e n t e n o a t e (44) i n a sea led N . M . R . tube w a s heated at o 258 f o r 50 h r . P r o d u c t a n a l y s i s b y V . P . C . u s i n g a 20' x 3 / 8 " d i n o n y l -phthalate c o l u m n at 155° w i t h h e l i u m f low of 85 m l per m i n showed three peaks at 14.7, 18.9 and 23.3 m i n r e s p e c t i v e l y . The f i r s t peak w a s the s t a r t i n g m a t e r i a l (<^5%), the second and the t h i r d peaks w i t h a ra t io of '"-'85:15 w e r e c h a r a c t e r i z e d to be m e t h y l 4 - m e t h y l - 4 - p e n t e n o a t e (70) and m e t h y l 4 - m e t h y l - 3 - p e n t e n o a t e (102). M e t h y l 4 - m e t h y l - 4 - p e n t e n o a t e (70): b . p . 1 4 9 ° , n 2 " 3 1.4230. Its N . M . R . s p e c t r u m shows f o u r s ing le t s at 8.25 't" (broad) f o r the C - 4 m e t h y l , 7.64 f f o r the C - 2 and C - 3 methylene h y d r o g e n s , 6.35 'X f o r the e s t e r m e t h y l and 5.20 X (broad) f o r the C - 5 t e r m i n a l methylene h y d r o g e n s . A n a l . C a l c d . f o r C ? H 2 O z : C , 65.49; H , 9.45. F o u n d : C , 65.67; H, 9 .53. M e t h y l 4 - m e t h y l - 3 - p e n t e n o a t e (102): i ts N . M . R . s p e c t r u m io i d e n t i c a l to that i s o l a t e d f r o m the t h e r m a l i s o m e r i z a t i o n of m e t h y l c i s -4 - m e t h y l - 2 - p e n t e n o a t e (44) as d i s c u s s e d l a t e r (p.100). - 93 -T h e r m a l r e a r r a n g e m e n t of m e t h y l t r a n s - 1 , 2 - d i m e t h y l - 1 - c y c l o p r o p a n e -c a r b o x y l a t e (18) at 3 0 0 ° A s a m p l e of 0.5 m l of 18 i n a sea led N . M . R . tube w a s heated at 3 0 0 ° f o r 18 h r . P r o d u c t a n a l y s i s b y V . P . C . us ing a 1 0 ' x 1/4" d i -nonylphthala te c o l u m n at 140° w i t h h e l i u m f low of 35 m l p e r m i n showed, that 18 had r e a r r a n g e d a l m o s t q u a n t i t a t i v e l y to m e t h y l 2 - m e t h y l - 4 - p e n -teno ate (31) (99%). M e t h y l 2 - m e t h y l - 4 - p e n t e n o a t e (31): b . p. 1 3 7 . 5 ° , n 2 / 2 1.4156. It showed N , M . R . peaks at ,6 .49 T (singlet) for the es ter m e t h y l , 8.97 T (doublet, j£±6.5 c .p . s . ) f o r the C - 2 m e t h y l , 7.35 T to 8.10 ' T (mult ip le t ) f o r the C - 2 and C - 3 h y d r o g e n s , 5.05 T and 5.26 " T (both m u l t i p l e t ) f o r the t e r m i n a l hydrogens and 4.15 ' V to 4.85 T (mult iplet ) f o r the C - 4 o l e f i n i c h y d r o g e n . A n a l . C a l c d . f o r C 7 H 1 2 0 2 : C , 65.49; H , 9.45. F o u n d : C , 65.68; H, 9.57. T h e r m a l r e a r r a n g e m e n t of m e t h y l t rans - 2 , 3 - d i m e t h y l - l - c y c l o p r o p a n e -c a r b o x y l a t e (36) at 2 5 8 ° T h r e e h u n d r e d m i c r o l i t e r s of 36 w a s heated at 25 8° f o r 5 0 h r i n a s e a l e d N . M . R . tube. V a p o r phase c h r o m a t o g r a p h y of p r o d u c t u s i n g a 1 0 ' x 1/4" dinonylphthalate c o l u m n at 150° w i t h h e l i u m f low of 35 m l p e r m i n gave m e t h y l 3 - m e t h y l - 4 - p e n t e n o a t e (71) and unchanged 36 i n a ra t io of 90:10 w i t h r e t e n t i o n t i m e s of 12.5 and 14.4 m i n r e s p e c t i v e l y . n 24 M e t h y l 3 - m e t h y l - 4 - p e n t e n o a t e ("71): b . p. 137.5 , n D 1.4152. - 94 -Its N . M . R . s p e c t r u m shows the C - 3 m e t h y l at 8.97 T (doublet, j -^-5.3 c . p . s . ) , the e s t e r m e t h y l at 6.41 t (s inglet) , the C-2 methylene hydrogens one at 7.79 ' T (doublet, J-^-8.6 c . p . s . ) and the other at 7.76 '7" (doublet, J — 5 . 8 c . p . s . ), the C - 3 h y d r o g e n at 7.35 T (mult iplet ) and the three o l e f i n i c h y d r o g e n s at 5.18 T , 4.95 T and 4.22 't (a l l m u l t i p l e t s ) . A n a l . C a l c d . f o r C 7 H i 2 0 2 : C , 65.49; H , 9.45. F o u n d : C , 65.58; K , 9.45. T h e r m a l r e a r r a n g e m e n t of methyl_cig_-2 -methyl-1 - c y c l o p r o p a n e -c a r b o x y l a t e (37) at 2 9 4 ° A s a m p l e (2 m l ) conta in ing 28.2% of 37 and 71.8% of m e t h y l t r a n s - 2 - m e t h y l - 1 - c y c l o p r o p a n e c a r h o x y l a t e (16) (100 M c N . M . R . s p e c -t r u m of the h i g h f i e l d r e g i o n of this m i x t u r e i s shown i n F i g u r e 16A) i n o a s e a l e d tube w a s heated at 294 f o r 18 h r to give two components H and J i n the r a t i o of <~'1:3. T h e y w e r e s e p a r a t e d b y V . P . C . u s i n g a 1 0 ' x I / 4 " U c o n p o l a r c o l u m n at 92° w i t h h e l i u m flow at 5 0 m l per m i n w i t h r e t e n -t ion t i m e s of 16.8 and 19.7 m i n r e s p e c t i v e l y . 2 2 C o m p o n e n t H : b . p. 1 2 5 . 5 ° , n ^ 1.4148. It w a s a s s i g n e d the s t r u c t u r e of m e t h y l 4-pentenoate (72) on the b a s i s of i t s N . M . R . s p e c -t r u m w h i c h shows three s ing le t s at 7.67 '•*, 7.62 '0 and 6.45 X and three seis ! of m u l t i p l e t s at 5.08 T, 4.84 ''v." and 4.09 A n a l . C a l c d . f o r C 6 H 1 Q 0 2 : C , 63.11; H , 8.84. F o u n d : C , 62.90; K, 8.81. o 25 Component J : b . p. 13 0.5 , 1.4195. It w a s a s s i g n e d the - 95 -F I G U R E 1 6 - A . 100 M c N . M . R/; s p e c t r u m of m i x t u r e of J57 and 16_ B . 100 M c N , M . R . s p e c t r u m of 16 - 96 -s t r u c t u r e of m e t h y l t rans -2 - m e t h y l - 1 - c y c l o p r o p a n e c a r b o x y l a t e (16) on the b a s i s that i t d i d not r e a r r a n g e on heat ing (5 h r at 2 9 4 ° ) . The 100 M c N . M . R . s p e c t r u m of the h i g h f i e l d r e g i o n of 16 i s shown i n F i g u r e l o B . A n a l . C a l c d . for C ^ H ^ C ^ : C , 63.11; H, 8.84. F o u n d : C , 63.40; H, 8.62. T h e r m a l r e a r r a n g e m e n t of m e t h y l c i s , t rans -1 ,2 ,3 - t r i m e t h y l -1 - c y c l o -p r o p a n e c a r b o x y l a t e (38) at 2 3 0 ° S i x h u n d r e d m i c r o l i t e r s of 38 ha a s e a l e d N . M . R . tube was heated at 2 8 0 ° f o r 12 h r . P r o d u c t a n a l y s i s b y V . P . C . u s i n g a 20" x 3 / 8 " d idecy lphtha la te c o l u m n at 168° w i t h h e l i u m f low at 85 m l p e r m i n gave 5% unchanged 38 and 95% of m e t h y l 2 , 3 - d i m e t h y l - 4 - p e n t e n o a t e (73) w i t h r e t e n t i o n t i m e s of 25,7 and 24.0 m i n r e s p e c t i v e l y . M e t h y l 2 , 3 - d i m e t h y l - 4 - p e n t e n o a t e (73): b . p. 1 5 1 . 5 ° , n ^ 1.4212. The N . M . R . s p e c t r u m shows peaks at 9.01 \ T (doublet, J-—6.6 c .p .s . ) f o r the C - 2 m e t h y l , 8.94 T (doublet, J __.6.7 c .p .s . ) f o r the C - 3 m e t h y l , 7.64 ' X (mult ip le t ) f o r the C - 2 and C - 3 me thine h y d r o g e n s , 6.38 ^ (singlet) for the e s t e r m e t h y l , 5.14 ' C , 4.92 T and 4.31 X ( a l l m u l t i p l e t s ) f o r the three o l e f i n i c h y d r o g e n s . A n a l . C a l c d . f o r C g H ^ C ^ : C , 67.57; H , 9.93. F o u n d : C , 67.47; K , 9.91. A t t e m p t e d t h e r m a l r e a r r a n g e m e n t of m e t h y l t r a n s - 2 - s l k y l - 1 - c y c l o p r o -. p a n e c a r b o x y l a t e 3 - 97 -S a m p l e s of s e v e r a l m e t h y l t r a n s - 2 - a l k y l - l - c y c l o p r o p a n e c a r b -oxylate s, i n sea led N . M . R , tubes, w e r e heated at t e m p e r a t u r e s above 2 5 0 ° and V. P . C , and N . M . R . ana lyses showed no r e a r r a n g e m e n t o c c u r r e d . These m e t h y l t rans - 2 - a l k y l - l - c y c l o p r o p a n e c a r b o x y l a t e s are l i s t e d be low w i t h t e m p e r a t u r e of r e a c t i o n and the length of heat ing i n b r a c k e t s : m e t h y l c i s -1 - m e t h y l - 2 - e t h y l - 1 - c y c l o p r o p a n e c a r b o x y l a t e (34} (280 , 18 h r ) , m e t h y l c i s - l , 2 - d i m e t h y l - l - c y c l o p r o p a n e c a r b o x y l a t e (17) (300 , 18 h r ) , m e t h y l t r a n s - 2 - m e t h y l - 1 - c y c l o p r o p a n e c a r b o x y l a t e (16) (294° , 23 hr ) and m e t h y l c i s , c i s - 1 , 2 , 3 - t r i m e t h y l - l - c y c l o p r o p a n e c a r b -oxylate (39) (230° , 12 h r ) . A t t e m p t e d t h e r m a l r e a r r a n g e m e n t of c i s - and t r a n s - 1 , 2 - d i m e t h y l -o - 1 - c y a n o c y c l o p r o p a n e (41 and 40) at 25 8 S a m p l e s of 41 and 40 i n sea led N . M . R . tubes w e r e heated a i 258° f o r 17 h r . No r e a r r a n g e m e n t o c c u r r e d to e i ther compound as i n -d i c a t e d b y both V . P . C . and N . M . R . a n a l y s e s . K i n e t i c s tudies of the t h e r m a l r e a r r a n g e m e n t of c y c l o p r o p a n e s The k i n e t i c s of the t h e r m a l r e a r r a n g e m e n t of m e t h y l c i s - 2 -a l k y l - 1 - c y c l o p r o p a n e c a r b o x y l a t e s to t h e i r c o r r e s p o n d i n g \/^-unsaturated e s t e r s had been s tudied at v a r i o u s t e m p e r a t u r e s ranging f r o m 24d°to 300? F o r each k i n e t i c r u n , 10 to 15 s a m p l e s w e r e heated at a d e s i r e d t e m -p e r a t u r e i n sea led tubes. The s a m p l e s , 7 :I each, w e r e p l a c e d i n pyre:-: tubes, 120 m m x 4 m m O. D . (the volume of each tube w a s a p p r o x i m a t e l y - 98 -0.5 ml ) and s e a l e d at a t m o s p l i e r i c p r e s s u r e . T h e y w e r e r e m o v e d at v a r i o u s t i m e i n t e r v a l s and quenched b y c o o l i n g w i t h ice w a t e r and a n a l y s e d b y V . P . C . A l l k i n e t i c runs w e r e f o l l o w e d to at l e a s t 70% c o m -p l e t i o n . T h e y gave good f i r s t - o r d e r k i n e t i c s and rate constants w e r e o b -ta ined f r o m f i r s t - o r d e r p l o t s . The heats of a c t i v a t i o n and e n t r o p i e s of a c t i v a t i o n w e r e obta ined b y g r a p h i c a l p r e s e n t a t i o n of the t e m p e r a t u r e dependence of rate constant (see text) . The r e s u l t s a r e s u m m a r i z e d i n Table V (p. 34 ). The f u r n a c e u s e d f o r the heat ing of the s a m p l e s w a s a v e r t i c a l c y l i n d r i c a l i n d u c t i o n f u r n a c e . S a m p l e tubes w e r e p l a c e d ins ide the m e t a l c y l i n d e r w h i c h w a s heated to the d e s i r e d t e m p e r a t u r e b y the heat ing c o i l a r o u n d i t . The e l e c t r i c a l input to the heat ing c o i l w a s c o n t r o l l e d b y an input c o n t r o l l e r . ( T e m c o m e t e r , t rade name of the t h e r m o E l e c t r i c C o . ). The t e m p e r a t u r e i n s i d e the f u r n a c e w a s m a i n t a i n e d to ± 0 . 5 ° of the d e s i r e d t e m p e r a t u r e w h i c h w a s o b s e r v e d b y a t h e r m o m t e r p l a c e d i n the same o l e v e l as the s a m p l e tubes . The t h e r m o m e t e r , 400 m m l e n g t h , -10 to + 4 0 0 ° range w i t h 1° s u b d i v i s i o n , had been c o r r e c t e d , f r o m 2 4 0 ° to 3 4 0 ° , ' aga ins t a s t a n d a r d t h e r m o m e t e r ( F i s h e r 2C4131 , N a t i o n a l B u r e a u of S tandard C a l i b r a t e d ) . The c h r o m a t o g r a p h i c uni t u s e d was an A e r o g r a p h M o d e l A - 9 0 - P w i t h t h e r m a l c o n d u c t i v i t y de tec tor . The c o l u m n s and a n a l y s i s condi t ions w e r e d i f f e r e n t f o r each of the c y c l o p r o p a n e - A ^ - o l e f i n s y s t e m as has been noted e a r l i e r under the t h e r m a l r e a r r a n g e m e n t of c y c l o p r o p a n e s . - 99 -C h . r o m a t o g r a m s v/ere r e c o r d e d on a H o n e y w e l l M o d e l S l e c t r o n i k 15 g r a p h i c r e c o r d e r and w e r e c o n v e r t e d to d i g i t a l data b y peak a r e a d e t e r -m i n a t i o n u s i n g a d i s c c h a r t i n t e g r a t o r . The response of the detec tor to the c y c l o p r o p a n e s and t h e i r ~g.^-olefins had been d e t e r m i n e d b y a n a l y z -ing 1:1 a n d / o r 2:1 m i x t u r e s of the two spec ies and w a s found to be accura te to l e s 3 than ± 1 % . A l l s a m p l e s of c y c l o p r o p a n e s and V, ^ - o l e f i n s u s e d f o r the k i n e t i c s tudies and the d e t e r m i n a t i o n of the response of the detec tor had been p u r i f i e d . b y V . P . C . to b e t t e r than 99.9% p u r i t y . P r e p a r a t i o n of m e t h y l 2 , 4 - d i m e t h y l - 3 - p e n t e n o a t e {1,01) A s a m p l e of 2 m l of m e t h y l c i s - 2 , 4 - d i m e t h y l - 2 - p e n t e n o a t e (42) i n a s e a l e d tube (220 m m x 6 m m I. D . ) w a s heated at 2 8 1 ° f o r 5 d a y s . V a p o r phase c h r o m a t o g r a p h y (10' x 1/4" dinonylphthalate c o l u m n at 160° w i t h h e l i u m f l o w of 35 m l per m i n ) a n a l y s i s showed that 90% of 42 i s o m e r i z e d to 101. M e t h y l 2 , 4 - d i m e t h y l - 3 - p e n t e n o a t e (101): b . p. 1 5 9 . 5 ° , n ^ 7 1.4280. The N . M . R . s p e c t r u m shows the C - 2 m e t h y l at 8.84 T (doublet, J J _ 7 . I c . p . s . ) , the C - 4 m e t h y l s at 8.34 "T and 8.28 'C (both doublet , J - ^ 1.4 c . p . s . ) , the e s t e r m e t h y l at 6.38 '~ (s inglet ) , the C - 2 methine h y d r o g e n at 6.76 C" (mult ip le t ) and the C - 3 o l e f i n h y d r o g e n at 4.89 (mul t ip le t ) . A n a l . C a l c d . f o r C g H ^ O . , : C , 6 7 . . 5 7 ; H , 9.93. F o u n d : C , 67.74; H , 9.92. — - 100 -P r e p a r a t i o n of m e t h y l 4 - m e t h y l - 3 _pentenoate (102) A s a m p l e of 1 m l of m e t h y l - b i s - 4 - m e t h y l - 2 - p e n t e n o a t e (44) i n a s e a l e d tube w a s heated at 2 9 4 ° f o r 3 h r . V a p o r phase c h r o m a t o g r a p h y (10' x 1/4" d inonylphthala te c o l u m n at 1 6 0 ° , h e l i u m f l o w of 35 m l per min) of the p r o d u c t showed m o r e than 97% of 44 i s o m e r i z e d to 102. M e t h y l 4 - m e t h y l - 3 - p e n t e n o a t e (102): b . p. 1 5 3 . 5 ° , n 2 2 1.4298 ( l i t . (91), .b. p. 1 4 5 - 8 ° at 640 m m , n ^ 3 1.4302). It showed N . M . R . peaks at 8.37 T and 8.26 T (both broad) f o r the C - 4 m e t h y l s , 6.40 T (s inglet) f o r the e s t e r m e t h y l , 7.08 T (doublet, Jr^.7.2 c .p . s . ) f o r the C - 2 m e t h y l -ene h y d r o g e n s and 4.75 T (mult iplet ) f o r the C - 3 o l e f i n h y d r o g e n . A n a l . C a l c d . f o r C ? H 1 2 0 2 : C , 65.59; H , 9.44. F o u n d : C , 65.49; H , 9.55. P r e p a r a t i o n of m e t h y l t r a n s - 2 - m e t h y l - 3 - p e n t e n o a t e . (103) One m i l l i l i t e r of m e t h y l c i s - 2 - m e t h y l - 2 - p e n t e n o a t e (46) i n a s e a l e d tube was heated at 2 9 4 ° f o r 85 h r . P r o d u c t a n a l y s i s b y V . P . C . u s i n g a 10' x 1/4" d inonylphthalate c o l u m n at 152° w i t h h e l i u m f low at 35 m l p e r m i n gave 18% of the s t a r t i n g o l e f i n 46, , 40% of m e t h y l yrans-2 - m e t h y l - p e n t e n o a t e (47) and 42% of 103. 2 3 M e t h y l t r a n s - 2 - m e t h y l - 3 - p e n t e n o a t e (103): b . p. 140° , n ' 1,4217 ( l i t . (3), b . p . 139, n 2 3 1.4229). The I. R . hands at 1734 c m " 1 and 971 c m * a r e c o n s i s t e n t w i t h the s t r u c t u r e of 103 . The N . M . R . s p e c t r u m showe"d the C - 2 m e t h y l at 8.31 ' X (doublet w i t h f ine s p l i t t i n g ) , the e s t e r m e t h y l at 6.39 T (s inglet) , the C - 2 methine h y d r o g e n at 7.00 "f - 101 -(mul t ip le t ) and the o l e f i n i c h y d r o g e n s at 4.51 T (mul t ip le t ) . A n a l . C a l c d . f o r C ? H 1 2 0 2 : C , 65.59; H , 9.44. F o u n d : C , 65.77; H , 9.63. P r e p a r a t i o n of m e t h y l t r a n s - 3 -per-.tenoa.te (94) A s a m p l e of 5 00 ^u l of m e t h y l c i s - 2 - p e n t e n o a t e (48) i n a s e a l e d tube w a s heated at 2 7 0 ° f o r 50 h r . A n a l y s i s b y V . P . C . u s i n g a 20' x 3 / 8 " d inonylphthala te c o l u m n at 15 0° w i t h h e l i u m f low of 5 0 m l per m i n gave 48, m e t h y l t r a n s - 2 - p e n t e n o a t e (49) and 94 i n the ra t io of 8:4-0:52, o 24 M e t h y l t r a n s - 3 - p e n t e n o a t e (_94): b . p . 131 , n 1.4196 ( l i t . (2), b . p . 1 3 6 ° , n 2 1 1.4220). The N . M . R . s p e c t r u m of 94 i s i d e n t i c a l to that D — r e p r t e d b y M c G r e e r et. a l . (2). T h e r m a l i s o m e r i z a t i o n , e q u i l i b r a t i o n and k i n e t i c s tudies of o le f ins The appara tus , g e n e r a l p r o c e d u r e and c o m p o s i t i o n a n a l y s i s w e : s i m i l a r to 'those e m p l o y e d f o r the c y c l o p r o p a n e s as d e s c r i b e d e a r l i e r i n this t h e s i s . E q u i l i b r a t i o n w a s c o n s i d e r e d r e a c h e d w h e n the p e r c e n t c o m -p o s i t i o n r e m a i n e d constant f o r a c o n s i d e r a b l e l ength of t i m e . F i r s t - o r d e r k i n e t i c s w a s o b s e r v e d f o r the i s o m e r i z a t i o n of m e t h y l c i s - 4 - m e t h y l - 2 -pentenoate (44) and m e t h y l c i s - 2 , 4 - d i m e t h y l - 2 - p e n t e n o a t e (42) to m e t h y l 4 - m e t h y l - 3 - p e n t e n o a t e (102) and m e t h y l 2 , 4 ~ d i m e t h y l - 3 - p e n t e i i o a t (101) x^espectively. T h e i r ra te constants , heats of a c t i v a t i o n and entropie of a c t i v a t i o n wer-e d e t e r m i n e d as d i s c u s s e d i n the text. - 102 -B I B L I O G R A P H Y 1. D . E . M c G r e e r , J . O r g . C h e m . , 25_, 852 (I960). 2. D . E . M c G r e e r , W . W a i and G . C a r m i c h a e l , C a n . J . C h e m . , 38, 2410 (1960). 3. D. E . M c G r e e r , P . M o r r i s and G. C a r m i c h a e l , C a n . J . C h e m . , 41_, 726 (1963). 4. D. E . M c G r e e r , R . S. M c D a n i e l and M . G . V i n j e , C a n . J . C h e m . , 43, 1389 (1965). 5. D. E . M c G r e e r , N . W . K . C h i u and M . G . V i n j e , C a n . J . C h e m . , 43, 1398 (1965). 6. D . E . M c G r e e r , N . W . K . C h i u , * M . G . V i n j e and K . C . K . Wong, C a n . J . C h e m . , _43, 1407 (1965). 7. D . E . M c G r e e r and W . S. W u , C a n . J . C h e m . , 45, 461 (1967). 8. R. H u i s g e n , A n g e w . C h e m . , 67, 439 (1955). 9. N . W . K . 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B a i r d , J . A m . C h e m . S o c , 8-2775 (1962). ~ 100. S. W . B e n s o n , " T h e F u n d a t i o n s of C h e m i c a l K i n e t i c s " , M c G r a w -H i l l , New Y o r k , I960, p. 92. - 108 -A P P E N D I X The ra te constants r e p o r t e d i n Tab le X and X I f o r the t h e r m a l i s o m e r i z a t i o n of c i s d, .^ -unsaturated e s t e r s to t h e i r /3,G i s o m e r s v/ere d e t e r m i n e d b y d i s r e g a r d i n g a l l o ther s low steps (see text) . Such a m e t h o d shows s l i g h t d e v i a t i o n f r o m the value obta ined through c a l c u l a t i o n b y t a k -ing into account a l l the p o s s i b l e s teps . The t h e r m a l i s o m e r i z a t i o n c a n be r e p r e s e n t e d as f o l l o w s ; ^ .. k l n k 2 o T C —- p k - l k - 2 w h e r e T - t r a n s c{,'i> i s o m e r , C = c i s ,P i s o m e r and p= p,0 i s o m e r . The rate equation, f o r the f o r m a t i o n of i s o m e r i s d p / dt = k 2 C - k_2 ko x< o r , l e t t i n g C = 1 - f$- T = I - S (T is s m a l l ) and L. = 5 3 . 9 (rat io of , £ , 4 1 5 k_2 i s o m e r to c i s ol,o i s o m e r at e q u i l i b r i u m f o r the s y s t e m 44 and 102) d A / d t = k , (1 - _ 5 i L 9 -^ z 53.9 On into••"nation i t . g i v e s k , = - 2 . 303x -ihl— l o g 5 4 - 9 , 54.9 T h e r e f o r e f o r the t h e r m a l i s o m e r i z a t i o n of 44 to 102, i c . io found :o b 7 . 2 2 2 x l 0 ~ 5 s e c ' j / and for 42 to 101, k £ equals to 3.021;-: 1 0 e c c " / . The d e v i a t i o n s are o n l y 2.2% and 1.4% r e s p e c t i v e l y , w h i c h are w i t h i n e x p e r i m e n t a l e r r o r s . 

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