Phase-Transfer Catalysis - ACS Publications - American Chemical

Chapter 1

Phase-Transfer Catalysis: An Overview Charles M. Starks

Downloaded by UNIV OF SOUTH AUSTRALIA on May 18, 2012 | http://pubs.acs.org Publication Date: December 19, 1987 | doi: 10.1021/bk-1987-0326.ch001

Vista Chemical Company, Ponca City, OK 74602 Uniquely interesting, complex and useful activities and phenomena occur at interfaces: one need only to look at the interfaces between the land, the atmosphere, and the sea to find this truth. The same truth occurs in chemical interfaces, although sometimes it is the lack of activity that draws our attention. In many chemical situations where two species cannot collide and therefore cannot react because they are separated by an interface, the lack of activity has been overcome by use of the technique of PHASE TRANSFER CATALYSIS (PTC), which not only allows reaction to occur, but often to occur in very selective ways. An early and clear example of PTC(1) demonstrated that the lack of reactivity between a mixture of 1-chlorooctane and aqueous sodium cyanide (without organic solvent) could be overcome by the use of a phase transfer agent, whose function was to transfer cyanide ion in reactive form from its normal aqueous phase into the chlorooctane phase. Use of a small amount of phase transfer agent makes the system catalytic, since the phase transfer agent can repeatedly transfer active cyanide ions into the organic phase for reaction with 1-chlorooctane. This sequence of steps is represented by equation 1, where Q+ represents a quaternary salt containing sufficiently long alkyl groups or other organic structure as to make QCN predominantly soluble in the organic phase. organic phase

CgHiyCl + Q+CN" f

ψ

CgHijCN + Q+Cl" \ (1) I + Q+Cl"

aqueous Cl" + Q+CN" r CN" phase ^ Other classic examples illustrating the use of quaternary salts as phase transfer catalysts were published by Makosza(2), and by Brandstrom(3.) . Subsequent development of crown ethers(4-7) and cryptands(7-8) as phase transfer catalysts gave PTC an entirely new dimension since now the inorganic reagent, as sodium cyanide in the above e q u a t i o n , need no l o n g e r be d i s s o l v e d i n w a t e r b u t c a n be used 0097-6156/87/0326-0001$06.00/0 © 1987 American Chemical Society

In Phase-Transfer Catalysis; Starks, C.; ACS Symposium Series; American Chemical Society: Washington, DC, 1987.


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PHASE-TRANSFER CATALYSIS

as a d r y s o l i d . T h i s development gave r i s e t o l i q u i d - s o l i d PTC as a p a r t n e r t o l i q u i d - l i q u i d PTC. S i n c e 1971 phase t r a n s f e r c a t a l y s i s has emerged as a b r o a d l y u s e f u l tool(9-16) . not o n l y i n organic chemistry, but a l s o i n i n o r g a n i c c h e m i s t r y ( 1 7 ) , f o r new a n a l y t i c a l a p p l i c a t i o n s ( 1 8 ) , i n electrochemistry(27a), photochemistry(27b), and especially in polymer chemistry.(21.27-31) The s u b s t a n t i a l number o f p u b l i c a t i o n s , p a t e n t s , r e v i e w s , and books (200 t o 400 p e r y e a r s i n c e 1980) concerned w i t h PTC i n b o t h s c i e n t i f i c and commercial a p p l i c a t i o n s a t t e s t s t o the h i g h l e v e l o f i n t e r e s t t h a t t h i s t e c h n i q u e has generated. Commercial usage o f PTC t e c h n i q u e s has i n c r e a s e d markedly d u r i n g the l a s t f i v e y e a r s n o t o n l y i n the number o f a p p l i c a t i o n s (currently estimated to be fifty to seventy-five different u s e s ( 2 2 ) ) , b u t a l s o i n the volume o f c a t a l y s t s consumed ( e s t i m a t e d to be about one m i l l i o n pounds p e r y e a r ( 2 2 ) ) and i n the volume o f p r o d u c t s m a n u f a c t u r e d ( e s t i m a t e d t o be f i f t y t o one hundred m i l l i o n pounds p e r y e a r ( 2 2 ) ) i n the U n i t e d S t a t e s a l o n e . Many i n d i c a t o r s p o i n t t o a d d i t i o n a l e x t e n s i v e commercial a p p l i c a t i o n s o f the PTC t e c h n i q u e a l l around the w o r l d , and these i n d i c a t o r s suggest t h a t future chemical manufacturing processes will more an more i n c o r p o r a t e PTC because o f i t s advantages o f s i m p l i c i t y , reduced consumption o f o r g a n i c s o l v e n t s and raw m a t e r i a l s , m i l d r e a c t i o n c o n d i t i o n s , s p e c i f i c i t y o f r e a c t i o n s c a t a l y z e d , and enhanced c o n t r o l over b o t h r e a c t i o n c o n d i t i o n s , r e a c t i o n r a t e s , and y i e l d s . For some c u r r e n t l y produced polymers PTC p r o v i d e s the o n l y r e a s o n a b l e and p r a c t i c a l commercial method o f m a n u f a c t u r e ( 2 2 ) . Enormous p r o g r e s s has been made i n r e c e n t y e a r s i n a l l a s p e c t s o f phase t r a n s f e r c a t a l y s i s , and the symposium on w h i c h t h i s volume i s b a s e d ( 2 3 ) was o r g a n i z e d t o p r o v i d e a sample o f some o f the advances i n t h r e e a r e a s : (1) t h e o r y and a p p l i c a t i o n o f the method; (2) d e s i g n o f s p e c i f i c c a t a l y s t s f o r i n c r e a s e d e f f i c i e n c y and s e l e c t i v i t y ; and (3) use o f PTC i n polymer c h e m i s t r y . The e x c e l l e n t c h e m i s t s and t h e i r co-workers who have most g e n e r o u s l y c o n t r i b u t e d to t h i s p u b l i c a t i o n p r e s e n t a b r o a d range o f work and v i e w p o i n t s w h i c h s t i m u l a t e and d e l i g h t those o f us who have a s t r o n g i n t e r e s t i n PTC. Applications The g e n e r a l concept o f phase t r a n s f e r c a t a l y s i s a p p l i e s t o the t r a n s f e r o f any s p e c i e s from one phase t o another (not j u s t anions as i l l u s t r a t e d above), p r o v i d e d a s u i t a b l e c a t a l y s t can be chosen, and p r o v i d e d s u i t a b l e phase c o m p o s i t i o n s and r e a c t i o n c o n d i t i o n s are used. Most p u b l i s h e d work u s i n g PTC d e a l s o n l y w i t h the t r a n s f e r o f a n i o n i c r e a c t a n t s u s i n g e i t h e r q u a t e r n a r y ammonium o r phosphonium salts, o r w i t h crown e t h e r s i n l i q u i d - l i q u i d o r liquid-solid systems. Examples o f the t r a n s f e r and r e a c t i o n o f o t h e r c h e m i c a l s p e c i e s have been r e p o r t e d ( 2 4 ) b u t c l e a r l y some o f the most i n n o v a t i v e work i n t h i s a r e a has been done by A l p e r and h i s co-workers, as described i n Chapter 2. He illustrates that g a s - l i q u i d - l i q u i d t r a n s f e r s w i t h complex c a t a l y s t systems p r o v i d e methods for catalytic hydrogénations w i t h gaseous hydrogen,



1. STARKS

Overview

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c a t a l y t i c o x i d a t i o n s w i t h gaseous oxygen, and c a r b o n y l a t i o n o f a l k y l h a l i d e s , o l e f i n s and a c e t y l e n e s w i t h c a r b o n monoxide. A p o r t i o n o f s u b s t a n t i a l t h e o r e t i c a l and h i s t o r i c a l importance i n PTC has c e n t e r e d around t h e q u e s t i o n o f 'what i s t h e n a t u r e o f the s p e c i e s t r a n s f e r r e d , and where i n t h e r e a c t i o n sequence do t h e s l o w s t e p s t a k e p l a c e . ' These q u e s t i o n s prompted much debate d u r i n g the e a r l y y e a r s o f PTC when development and u n d e r s t a n d i n g o f t h e r e a c t i o n sequence and mechanism o f PTC was emerging. I t g e n e r a l l y came t o be r e c o g n i z e d t h a t s m a l l changes i n t h e complex sequence o f s t e p s o f even t h e s i m p l e s t phase t r a n s f e r c a t a l y z e d system c a n result i n differing kinetics, differences i n optimal catalyst s t r u c t u r e , and d i f f e r e n t o p t i m a l r e a c t i o n c o n d i t i o n s , even f o r s i m i l a r r e a c t i o n s . Of p a r t i c u l a r i n t e r e s t i n t h i s volume i s Chapter 3 by L i o t t a and co-workers, who have found t h a t even t h e amount o f w a t e r p r e s e n t i n l i q u i d - s o l i d PTC may s u b s t a n t i a l l y a f f e c t the s i t e where f i n a l r e a c t i o n o c c u r s . These o b s e r v a t i o n s have l e d L i o t t a t o p o s t u l a t e a new phase i n w h i c h r e a c t i o n may occur. M o n t a n a r i and co-workers, who have been p r o l i f i c c o n t r i b u t o r s i n PTC, have a l s o p r o v i d e d (Chapter 6) s i g n i f i c a n t i n s i g h t i n t o t h e e f f e c t o f w a t e r on PTC r e a c t i o n s . I n a s e r i e s o f h i g h l y u s e f u l a p p l i c a t i o n s phase t r a n s f e r c a t a l y s i s has g i v e n t h e c h e m i s t t h e a b i l i t y t o conduct r e a c t i o n s between o r g a n i c compounds and s t r o n g i n o r g a n i c o x i d a n t s such as permanganate, d i c h r o m a t e , h y p o c h l o r i t e , and hydrogen p e r o x i d e ( 2 5 ) . Use o f t h e s e o x i d a n t s p r e v i o u s l y has been l i m i t e d and e x p e r i m e n t a l l y i n c o n v e n i e n t because o f t h e narrow range o f s t a b l e o r g a n i c s o l v e n t s w h i c h one c o u l d use t o b r i n g t h e o x i d a n t s and s u b s t r a t e into c o n t a c t . The power o f PTC f o r permanganate o x i d a t i o n s and t h e use o f PTC t o s t u d y t h e mechanism o f t h e s e o x i d a t i o n s i s demonstrated by Lee i n Chapter 8. C a t a l y s t Improvements A l t h o u g h q u a t e r n a r y ammonium s a l t s , phosphonium s a l t s , crown e t h e r s , and c r y p t a n d s a r e g e n e r a l l y e x c e l l e n t c a t a l y s t s f o r most PTC a p p l i c a t i o n s , t h e r e a r e many p o t e n t i a l PTC a p p l i c a t i o n s where these agents have deficiencies. F o r example, ordinary tetraalkyl q u a t e r n a r y s a l t s decompose a t h i g h temperatures (greater than 120-149°C), o r a t low temperatures under h i g h l y a l k a l i n e c o n d i t i o n s o r i n t h e p r e s e n c e o f h i g h l y n u c l e o p h i l i c a n i o n s such as phenoxide. Crown e t h e r s and c r y p t a n d s a r e s t a b l e under t h e s e c o n d i t i o n s b u t a r e much more e x p e n s i v e (100 t o 1000 f o l d c o s t ) t h a n q u a t e r n a r y s a l t s , and f o r p r a c t i c a l commercial use they must be c o m p l e t e l y r e c o v e r e d f o r r e - u s e . Open-chain p o l y e t h e r s , m a i n l y p o l y e t h y l e n e glycols, c a t a l y z e some k i n d s o f two-phase r e a c t i o n s , a r e s t a b l e and a r e q u i t e low i n c o s t , b u t t h e i r l i m i t e d u t i l i t y s u b s t a n t i a l l y r e s t r i c t s t h e i r a p p l i c a t i o n t o a narrow range o f r e a c t i o n s . The p o s s i b i l i t y o f s o l v i n g t h e c a t a l y s t r e c o v e r y problem by attaching a c t i v e c a t a l y s t centers to i n s o l u b l e polymeric substrates was r e c o g n i z e d e a r l y ( 2 6 ) , as was t h e p o s s i b l e use o f c h i r a l PTC c a t a l y s t s t o i n t r o d u c e c h i r a l i t y i n p r o d u c t s ( 1 ) . Much work i n b o t h t h e s e a r e a s has been p a r t i a l l y s u c c e s s f u l ( 2 7 ) . However, t h e r e s u l t s have n o t been c o m p l e t e l y s a t i s f a c t o r y i n t h a t r e s i n bound c a t a l y s t s have shown much lower c a t a l y t i c a c t i v i t y t h a n s o l u b l e c a t a l y s t s and they f r e q u e n t l y l o s e t h e i r a c t i v i t y w i t h repeated use. C h i r a l



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c a t a l y s t s g e n e r a l l y g i v e p r o d u c t s low c h i r a l s e l e c t i v i t y , w i t h enantiomeric excesses u s u a l l y l e s s than f i f t y percent. A f u r t h e r problem i n PTC has been t h a t no r e a l l y s u p e r i o r c a t a l y s t s have been i n t r o d u c e d f o r use w i t h d i v a l e n t o r t r i v a l e n t a n i o n s , o r w i t h the d i f f i c u l t t r a n s f e r a b l e hydroxide anion. I n f a c e o f the above d i s c o u r a g i n g r e s u l t s , r e c e n t i n n o v a t i v e c a t a l y s t work has l e d t o h i g h l y e f f e c t i v e s o l u t i o n s f o r some o t h e r w i s e v e r y d i f f i c u l t and e x p e n s i v e problems. F o r example, D o l l i n g and co-workers (Chapter 7) have shown t h a t by c a r e f u l c h o i c e of PTC c a t a l y s t and use o f o p t i m a l r e a c t i o n c o n d i t i o n s one can obtain high c h i r a l s e l e c t i v i t y ( g r e a t e r t h a n 90% e n a n t i o m e r i c e x c e s s ) and have a p p l i e d t h i s c h e m i s t r y t o a commercial p r o c e s s f o r p r o d u c t i o n o f the d i u r e t i c drug c a n d i d a t e I n d a c r i n o n e . B r u n e l l e , i n Chapter 5, has p r o v i d e d a s o l u t i o n t o the problem of q u a t e r n a r y ammonium c a t a l y s t s being unstable at elevated t e m p e r a t u r e s i n the presence o f h i g h l y n u c l e o p h i l i c a n i o n s . He found that catalysts based on p-dialkylaminopyridinium salts are approximately one hundred times more stable than simple t e t r a a l k y l a m m o n i u m s a l t s and a r e u s e f u l even up t o temperatures o f 180°C. E s p e c i a l l y v a l u a b l e i s the f a c t t h a t under t h e s e c o n d i t i o n s a v a r i e t y o f n u c l e o p h i l i c d i s p l a c e m e n t r e a c t i o n s on a r y l h a l i d e s o c c u r s , making p o s s i b l e the e c o n o m i c a l commercial s y n t h e s i s o f o t h e r w i s e d i f f i c u l t y a v a i l a b l e p o l y a r y l e t h e r s and s u l f i d e s . B r u n e l l e , Chapter 5, a l s o demonstrated t h a t b i s - q u a t e r n a r y s a l t s w i t h a p p r o p r i a t e s p a c i n g between the q u a t e r n a r y n i t r o g e n s are d r a m a t i c a l l y b e t t e r t h a n mono-quaternary s a l t s as c a t a l y s t s f o r t r a n s f e r o f d i v a l e n t a n i o n s , such as the d i - a n i o n o f b i s p h e n o l A. Thus t h e i o n p a i r formed from the d i - a n i o n and a b i s - q u a t appears t o be more e a s i l y formed and t r a n s f e r r e d t h a n the s p e c i e s formed from the d i - a n i o n and two mono-quaternary c a t i o n s . Idoux and co-workers, Chapter 14, have also prepared h i g h - a c t i v i t y m u l t i - s i t e phase t r a n s f e r c a t a l y s t s bound t o i n s o l u b l e r e s i n s . A l t h o u g h n o t y e t e x p e r i m e n t a l l y demonstrated, t h i s type o f c a t a l y s t may a l s o be u s e f u l f o r t r a n s f e r r i n g m u l t i v a l e n t a n i o n s such as c a r b o n a t e , s u l f i t e , s u l f i d e , s u l f a t e o r phosphate, s i n c e the compounds used have two phosphonium c a t i o n i c c e n t e r s i n c l o s e p r o x i m i t y t o each o t h e r . However, t h e s e workers p r e s e n t work which shows t h a t a m u l t i - s i t e c a t a l y s t can e x h i b i t g r e a t e r s e l e c t i v i t y i n d i s p l a c e m e n t on o r g a n i c r e a g e n t s c o n t a i n i n g two d i s p l a c e a b l e groups. M o n t a n a r i and co-workers, Chapter 6, have d e v e l o p e d s p e c i a l c y c l i c e t h e r s w h i c h , when p r o p e r l y bound t o c r o s s - l i n k e d r e s i n s , exhibit a h i g h degree of catalytic effectiveness, generally comparable t o t h a t o f s o l u b l e q u a t e r n a r y ammonium and phosphanium s a l t s . This great increase i n a c t i v i t y f o r resin-bound c a t a l y s t s r e p r e s e n t s a b r e a k t h r o u g h development, and a l t h o u g h t h e s e c a t a l y s t s would be h i g h l y e x p e n s i v e , t h e i r a b i l i t y t o m a i n t a i n h i g h a c t i v i t y a f t e r r e p e a t e d use and f o r extended t i m e s i n c o n t i n u o u s r e a c t o r s would m i t i g a t e t h e i r i n i t i a l c o s t and a v o i d the problem o f c a t a l y s t removal from p r o d u c t s . T a k i n g an e n t i r e l y d i f f e r e n t t a c k on s u p p o r t e d phase t r a n s f e r c a t a l y s t s , S a w i c k i , Chapter 12, i n i t i a l l y used p o l y e t h e r s c h e m i c a l l y bound t o s i l i c a . But, he a l s o demonstrated t h a t s o l i d s i l i c a o r a l u m i n a a l o n e may f u n c t i o n as l i q u i d - s o l i d phase t r a n s f e r c a t a l y s t s , p r o b a b l y t h r o u g h mechanisms e n t i r e l y d i f f e r e n t t h a n the c l a s s i c a l PTC sequence.


1. STARKS

Overview

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E x p l o r a t i o n by G o k e l and co-workers, Chapter 4, o f a d i v e r s e s e t o f p o l y e t h e r s t r u c t u r e s and t h e i r a b i l i t y t o b i n d w i t h c a t i o n s has p r o v i d e d compounds w h i c h have many p o t e n t i a l a p p l i c a t i o n s f o r use i n PTC.


Phase T r a n s f e r C a t a l y s i s i n Polymer C h e m i s t r y A s i d e from the use o f polymers as s u p p o r t s f o r phase t r a n s f e r c a t a l y s t c e n t e r s , much e x c e l l e n t work has been r e p o r t e d on the use o f PTC i n polymer c h e m i s t r y f o r p o l y m e r i z a t i o n methods(28), f o r the chemical m o d i f i c a t i o n of already formed p o l y m e r s ( 2 9 ) , f o r the m o d i f i c a t i o n o f polymer s u r f a c e s without change o f the bulk polymer(30), and for the preparation and purification of monomers(31). Rasmussen and co-workers, Chapter 10, have shown t h a t many f r e e - r a d i c a l p o l y m e r i z a t i o n s can be conducted i n two-phase systems u s i n g p o t a s s i u m p e r s u l f a t e and e i t h e r crown e t h e r s o r quaternary ammonium s a l t s as i n i t i a t o r s . When t r a n s f e r r e d t o the o r g a n i c phase p e r s u l f a t e p e r f o r m s f a r more e f f i c i e n t l y as an i n i t i a t o r than c o n v e n t i o n a l m a t e r i a l s such as a z o b i s i s o b u t y r o n i t r i l e o r benzoyl peroxide. In v i n y l polymerizations using PTC-persulfate initiation one can e x e r c i s e p r e c i s e c o n t r o l over r e a c t i o n r a t e s , even a t low t e m p e r a t u r e s . M e c h a n i s t i c a s p e c t s o f t h e s e c o m p l i c a t e d systems have been worked out f o r t h i s h i g h l y u s e f u l and e c o n o m i c a l method o f i n i t i a t i o n of f r e e - r a d i c a l polymerizations. Production of polymers through poly-substitution or poly-condensation r e a c t i o n s would be e x p e c t e d t o be a n a t u r a l e x t e n s i o n o f s i m p l e PTC c h e m i s t r y . To a l a r g e e x t e n t t h i s i s t r u e , b u t as P e r c e c has shown, Chapter 9, the a b i l i t y t o use two-phase systems f o r t h e s e r e a c t i o n s has enormously extended the c h e m i s t ' s a b i l i t y t o c o n t r o l the s t r u c t u r e o f the polymers produced. K e l l m a n and co-workers (Chapter 11) have also extensively studied p o l y - s u b s t i t u t i o n d i s p l a c e m e n t s on p e r f l u o r o b e n z e n e substrate to produce unique polymers. The s i m p l e r e a c t i o n o f polymers w i t h i n o r g a n i c r e a g e n t s has h i s t o r i c a l l y been a d i f f i c u l t c h e m i c a l problem and g e n e r a l l y such t r a n s f o r m a t i o n s have been f a r too e x p e n s i v e t o p r a c t i c e on a commercial s c a l e . The use o f PTC makes t h i s k i n d o f problem v a s t l y s i m p l e r , as i n n o v a t i v e l y demonstrated i n an a d a p t a t i o n by N i c h o l a s (Chapter 13), t o f i n d l o w - c o s t c h e m i s t r y f o r c o n v e r t i n g s c r a p rubber i n t o a m a t e r i a l more n e a r l y r e s e m b l i n g the s t r u c t u r e o f new r u b b e r . PTC

Development

About t e n y e a r s ago a knowledgeable o r g a n i c c h e m i s t o f f e r e d the o p i n i o n t h a t "almost a l l the t h i n g s t h a t can be done v i a phase t r a n s f e r c a t a l y s i s has a l r e a d y been done." He was wrong, o f c o u r s e , as one can now l o o k back and see t h a t the g r e a t b u l k o f PTC c h e m i s t r y now known came a f t e r h i s comment was made. W h i l e i t may be t r u e t h a t many o f the o b v i o u s and d i r e c t a p p l i c a t i o n s o f PTC, e s p e c i a l l y f o r a n i o n t r a n s f e r , have been i d e n t i f i e d , i t seems most l i k e l y t o t h i s a u t h o r t h a t a v a s t amount o f new a p p l i c a t i o n s and more complex c a t a l y s t systems based on PTC a w a i t d i s c o v e r y and exploitation.



6 References 1. 2.

3.


4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19.

20.

21.

C. M. Starks, J. Am. Chem. Soc., 93, 195 (1971). M. Makosza, "Reactions of Carbanions and Halogenocarbenes in Two-Phase Systems," Russian Chem. Revs. 46, 1151 (1977); "Two-Phase Reactions in Organic Chemistry" in Survey of Progress in Chemistry, Vol. IX, (1979) Academic Press, New York, and references contained therein. A Brandstrom, "Principles of Phase-Transfer Catalysis by Quaternary Ammonium Salts," Adv. Phys. Org. Chem. 15, 267 (1977). A. W. Herriott and D. Picker, J. Am. Chem. Soc. 97, 2345 (1975). C. L. Liotta and H. P. Harris, J. Am. Chem. Soc. 95, 2250 (1974). G. W. Gokel, D. J. Cram, C. L. Liotta, H. P. Harris, and F. L. Cook, J. Org. Chem. 39, 2445 (1974). F. Montanari, Chim. Ind. (Milan) 57, 17 (1975). R. Fornasier and F. Montanari, Tetrahedron Lett. 1381 (1976). A Brandstrom, "Preparative Ion Pair Extraction," Apotekarsocieteeten/Hassle Lakemedel, Sweden, 1974. W. P. Weber and G. W. Gokel, "Phase Transfer Catalysis in Organic Synthesis," Springer Verlag, New York 1977. R. A. B. Bannard, "Phase Transfer Catalysis and Some of its Applications to Organic Chemistry," U.S. Dept. of Commerce NITS AD-A-030 503, July, 1976. E. A. Dehmlow and S. S. Dehmlow, "Phase Transfer for Catalysis," Chem. Verlag 1983 C. M. Starks and C. L. Liotta, "Phase Transfer Catalysis, Principles and Techniques," Academic Press, New York, 1978. J. M. McIntosh, "Phase Transfer Catalysis Using Quaternary Onium Salts," J. Chem. Educ. 55, 235 (1978). G. W. Gokel and W. P. Weber, "Phase Transfer Catalysis," J. Chem. Educ. 55, 350 (1978). W. E. Keller, "Compedium in Phase Transfer Reactions and Related Synthetic Methods," Fluka, Switzerland (1979). H. H. Freedman, "Industrial Applications of Phase Transfer Catalysis, Past, Present, and Future," in press. R. M. Izatt and J. J. Christensen, "Synthetic Multidentate Macrocyclic Compounds," Academic Press, New York, 1978. N. A. Gibson and J. W. Hosking, Aust. J. Chem. 18, 123 (1965). For electrochemical applications of PTC see the following and references contained therein: E. Laurent, R. Rauniyar, and M. Tomalla, J. Appl. Electrochem. 14, 741 (1984): 15, 121 (1985). S. R. Ellis, D. Pletcher, W. M. Brooks, and K. P. Healy, J. Appl. Electrochem., 13, 735 (1983). Asahi Chemical Industry Co., Ltd., Japanese Patent Kokai 58/207382 (1982). For photochemical applications of PTC see the following references and references contained therein: Z. Goren and I. Willner, J. Am. Chem. Soc. 105, 7764 (1983). T. Kitamura, S. Kobayashi, and H. Taniguchi, J. Org. Chem. 49, 4755 (1984). F. L. Cook and R. W. Brooker, "Polymer Syntheses Employing Phase Transfer Catalysis," Polym. Prepr., Am. Chem. Cos., Div. Polym. Chem., 23, 149 (1982).


1. STARKS

Overview


22.

1

Estimates of commercial use were compiled by the author from a collection of non-published sources. 23. Symposium on Advances in Phase Transfer Catalysis, American Chemical Society Meeting, September 9, 1985, Chicago, sponsored by the Petroleum Chemistry Division. 24. A. Suzuki, T. Nakata, and W. Tanaka, Japanese Patent 70/10,126; C.A. 73, 44885 (1970). L. O. Esayan and Sh. O. Badanyan, Arm. Khim. Zh. 28, 75 (1975); C. A. 83, 9062 (1975). P. S. Hallman, B. R. McGarvey, and G. Wilkinson, J . Chem. Soc. A. 3143 (1968). H. M. van Dort and H. J . Geurse, Rec. Trav. Chim. Pays-Bas 86, 520 (1967). 25. For application of PTC with strong inorganic oxidants, see the following references and references contained therein: O. Bortolini, F. Di Furia, G. Modena, and R. Seraglia, J . Org. Chem. 50, 2688 (1985). H. E. Fonouni, S. Krishnan, D. G. Kuhn, and G. A. Hamilton, J . Am. Chem. Soc., 105, 7672 (1983). H. Alper, Adv. Organomet. Chem., 19, 183 (1981). 26. S. L. Regan, J . Am. Chem. Soc., 97, 5956 (1975). 27a. For reviews on the use of polymer-supported phase transfer catalysts, see: W. T. Ford, Adv. Polym. Sci. 55, 49 (1984); Polym. Sci & Tech., 24, 201 (1984). D. C. Sherrington, Macromol. Chem. (London) 3, 303 (1984). 27b. For use of chiral phase transfer catalysts see the following references and references contained therein: J . W. Verbicky Jr., and E. A. O'Neil, J . Org. Chem., 50, 1786 (1985); E. Chiellini, R. Solaro, and S. D'Antone, Polym. Sci. Technol. (Plenum), 24 (Crown Ethers Phase Transfer Catal. Polym. Sci.) 227 (1984). 28. For use of phase transfer catalysts in polymerization reactions see the following references and references contained therein: Y. Imai and M. Ueda, Polym. Sci. Technol. (Plenum), 24 (Crown Ethers Phase Transfer Catal. Polym. Sci.) 121 (1984); R. Bacskai, ibid 183; F. L. Cook and R. W. Brooker, Polym. Prepr. (Am. Chem. Soc., Div. Polym. Chem), 23, 149 (1982); C. E. Carraher, J r . , and M. D. Naas, ibid 158; A. Jayakrishnan and D. O. Shah, J . Polym. Sci., Polym. Chem. Ε., 21, 3201 (1983); J . Appl. Polym. Sci., 29, 2937 (1984). 29. For phase transfer catalyzed chemical reactions of polymers see the following references and references contained therein: J. M. J . Frechet, Polym. Sci. Technol (Plenum), 24 (Crown Ethers Phase Transfer Catal. Polym. Sci.), 1 (1984); G. Martinez, P. Terroba, C. Mijangos, and J . Millan, Rev. Plast. Mod., 49, 63 (1985); F. F. He and H. Kise, Makromol. Chem., 186, 1395 (1985); W.H. Daly, J . D. Caldwell, V. P. Kien, and R. Tang, Polym. Prepr. (Am. Chem Soc., Div. Polym. Chem.) 23, 145 (1982); D. C. Sherrington, Macormol. Chem. (London), 3, 303 (1984). 30. For use of phase transfer catalysis in modification of the surface of polymers see: A. J . Dias and T. J . McCarthy, Polym. Mater. Sci. Eng., 49, 574 (1983); Macromolecules, 17, 2529 (1984); H. Kise and H. Ogata, J . Polym. Sci., Polym. Chem. Ed., 21, 3443 (1983). 31. For an example of the use of phase transfer catalysis in monomer purification see: J . T. Fenton, U.S. Patent 4,423,238 (1983). RECEIVED August 12, 1986 In Phase-Transfer Catalysis; Starks, C.; ACS Symposium Series; American Chemical Society: Washington, DC, 1987.

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