Ozone Oxidation of Sulfides and Sulfoxides ALLISON M A G G I O L O and E. ALLAN BLAIR
Downloaded by UNIV OF BATH on October 28, 2014 | http://pubs.acs.org Publication Date: January 1, 1959 | doi: 10.1021/ba-1959-0021.ch030
Ozone Processes Division, Welsbach
Corp., Philadelphia,
Pa.
The stepwise oxidation of organic sulfides to sulfoxides a n d sulfones with ozone is reported. In the case of carboxymethylmercaptosuccinic a c i d , it is the only successful oxidation to the sulfoxide known. The yields in most cases are essentially quantitative with respect to both the sulfur compound a n d ozone.
I he f o r m a t i o n of d i a l k y l a n d a l k y l a r y l sulfones, a n d i n some cases t h e i r i n t e r m e d i a t e s u l f o x i d e s , b y t h e o x i d a t i o n of sulfides w i t h ozone has been d e s c r i b e d i n t h e l i t e r a t u r e {2, 6). H o w e v e r , n o m e n t i o n w a s m a d e as t o t h e a m o u n t s of ozone r e q u i r e d f o r these o x i d a t i o n s . I n a n excellent p a p e r (1) o n t h e use of ozone as a t i t r i m e t r i c agent f o r olefinic d o u b l e b o n d s , B o e r a n d K o o y m a n state t h a t , u n d e r t h e c o n d i t i o n s s t u d i e d , d i a l k y l sulfides c o n s u m e ^4 t o % m o l e of ozone p e r m o l e of sulfide a n d d i b e n z o t h i o p h e n e consumes 1 m o l e . N o n e of these o z o n a t e d p r o d u c t s w a s a n a l y z e d as t o i t s s u l f o x i d e o r sulf one c o n t e n t . T h e p r e s e n t i n v e s t i g a t i o n shows t h a t ozone reacts w i t h d i a l k y l a n d d i a r y l sulfides according to the equation : I\S 4 0
2
+ R SO 4 0 2
2
+
R 2 S O 2
W h e n r u n i n n o n p o l a r s o l v e n t s , t h e r e a c t i o n i s s t o i c h i o m e t r i c i n t h e f o r m a t i o n of b o t h a l i p h a t i c a n d a r o m a t i c sulfoxides a n d a l i p h a t i c sulfones. T h e r e a c t i o n w a s c a r r i e d o u t o n n u m e r o u s a r o m a t i c a n d a l i p h a t i c sulfides a n d s u l f o x i d e s . A m o n g t h e c o m p o u n d s m a d e i n e s s e n t i a l l y q u a n t i t a t i v e y i e l d s were d i b e n z y l s u l f o x i d e , d i b e n z y l s u l f o n e , d i m e t h y l sulfone, d i p h e n y l s u l f o x i d e , t h i o n y l d i g l y c o l i c a c i d , and carboxymethylthionylsuccinic acid (Table I ) .
10.7 grams
2.33 grams
+ 10.7 grams
0
11.3 grams
3
4.71 grams 200
12.0 grams
In OZONE CHEMISTRY AND TECHNOLOGY; Advances in Chemistry; American Chemical Society: Washington, DC, 1959.
M A G G I O L O A N D BLAIR—OXIDATION OF SULFIDES A N D SULFOXIDES
Table I.
Yields from Ozonization Experiments
Sulfide
Sulfoxide, % 98
Dibenzyl Dimethyl (sulfoxide) Diphenyl Dibenzothiophene Thiodiglycolic acid Carboxymethylmercaptosuccinic
Downloaded by UNIV OF BATH on October 28, 2014 | http://pubs.acs.org Publication Date: January 1, 1959 | doi: 10.1021/ba-1959-0021.ch030
201
95
acid
98 98
Sulfone, % 98 90 Colored product showing attack other than on sulfur atom Same as diphenyl sulfide No oxidation beyond sulfoxide
S o m e d i f f i c u l t y w a s e n c o u n t e r e d i n t h e f o r m a t i o n of a r o m a t i c sulfones. When t h e o z o n a t i o n w a s c a r r i e d o u t i n c h l o r o f o r m i n a r e a c t o r u s i n g a glass f r i t f o r t h e d i s p e r s i o n of ozone, a s o l i d p r e c i p i t a t e d w h i c h clogged t h e f r i t as t h e s e c o n d e q u i v a l e n t of ozone w a s a d d e d . I n acetic a c i d t h e r e w a s n o p r e c i p i t a t e , b u t t h e p r o d u c t f r o m t h e a d d i t i o n of t w o e q u i v a l e n t s of ozone w a s c o l o r e d a n d c o n t a i n e d b o t h t h e s u l f o x i d e a n d t h e s u l f o n e . I n a r e a c t o r i n w h i c h t h e ozone w a s d i s p e r s e d b y a h i g h - s p e e d s t i r r e r , t h e p r e c i p i t a t e f o r m e d i n c h l o r o f o r m d i d n o t i n t e r f e r e w i t h t h e a d d i t i o n of ozone, b u t t h e r e s u l t s w e r e t h e s a m e as t h e y were i n acetic a c i d . A t t e m p t s t o o x i d i z e d i p h e n y l sulfide a n d d i b e n z o t h i o p h e n e c l e a n l y t o t h e sulfones u s i n g s e v e r a l s o l v e n t s a n d ozone o r h y d r o g e n p e r o x i d e as t h e o x i d i z i n g agents g a v e t h e same r e s u l t s . M o r e w o r k o n t h i s p h a s e i s clearly indicated. C a r b o x y m e t h y l m e r c a p t o s u c c i n i c a c i d a n d t h i o d i g l y c o l i c a c i d were o x i d i z e d c l e a n l y t o t h e i r r e s p e c t i v e s u l f o x i d e s , b u t t h i o d i g l y c o l i c a c i d c o u l d n o t b e o x i d i z e d t o i t s sulfone a t r o o m t e m p e r a t u r e i n c h l o r o f o r m , acetic a c i d , a c e t o n i t r i l e , o r w a t e r c o n t a i n i n g m o l y b d a t e i o n . T h i s i s n o d o u b t d u e t o t h e s l o w r a t e o f o x i d a t i o n of t h e s u l f o x i d e t o t h e s u l f o n e , w h i c h c a n r e a d i l y b e e x p l a i n e d o n t h e basis of e l e c t r o n i c t h e o r y . T h i s i s a p p a r e n t l y t h e first successful p r e p a r a t i o n o f c a r b o x y m e t h y l t h i o n y l s u c c i n i c a c i d b y a n y m e t h o d (3). T h e w e l l - c o n t r o l l e d a t t a c k o f ozone o n t h e s u l f u r m o l e c u l e c a n best b e e x p l a i n e d b y t h e a s s u m p t i o n t h a t a t e r m i n a l o x y g e n of t h e ozone m o l e c u l e executes a n e l e c t r o p h i l i c attack o n the sulfur, f o r m i n g a new b o n d w i t h the sulfur. [Compare with Meinwald's w o r k (4) f o r t h e a n a l o g y i n t h e a t t a c k of ozone o n t h e d o u b l e b o n d . ] T h e r e u p o n , t h e second a n d t h i r d a t o m s o f t h e ozone a r e l i b e r a t e d as m o l e c u l a r o x y g e n . This theory e x p l a i n s t h e f a c t t h a t o n l y one o x y g e n f r o m e a c h ozone m o l e c u l e i s a d d e d t o t h e s u l f u r . I f one assumes a n a t t a c k o f t h e a p e x o x y g e n of t h e ozone m o l e c u l e , i t i s d i f f i c u l t t o u n d e r s t a n d w h y o n l y one o f t h e o x y g e n a t o m s s t a y s a s s o c i a t e d w i t h t h e s u l f u r . A l t h o u g h t h e c o n f i g u r a t i o n o f ozone w h i c h has a p o s i t i v e c h a r g e o n one t e r m i n a l o x y g e n a n d a n e g a t i v e charge o n t h e o t h e r , as o p p o s e d t o a p o s i t i v e c h a r g e o n t h e apex oxygen a n d a negative charge o n a t e r m i n a l oxygen, contributes little t o t h e s t r u c t u r e o f t h e m o l e c u l e (6), a n a n a l o g y c a n b e d r a w n w i t h o t h e r i o n i c a d d i t i o n r e a c t i o n s . T h e i o n i c c o n f i g u r a t i o n of t h e b r o m i n e m o l e c u l e c o n t r i b u t e s l i t t l e t o i t s s t r u c t u r e , y e t i t a d d s t o a n olefin first as a b r o m i n e c a t i o n . I n t h e course of these s t u d i e s t h e m o s t c o n v e n i e n t a p p a r a t u s i n w h i c h t o r u n these r e a c t i o n s w a s f o u n d t o b e a flask w i t h a s t i r r e r w h i c h has a gas i n l e t t h r o u g h i t . T h i s gives as g o o d a d i s p e r s i o n o f t h e gas i n t h e l i q u i d as does a f r i t t e d glass diffuser, a n d greatly simplifies t h e manipulations accompanying t h e reaction. I t has t h e a d d i t i o n a l a d v a n t a g e t h a t a n i n s o l u b l e p r o d u c t , i f f o r m e d , does n o t i n t e r f e r e w i t h t h e c o n t i n u a t i o n of the reaction. Literature
Cited
(1) Boer, H., Kooyman, F. C., Anal. Chim. Acta 5, 550-62 (1951). (2)
Bohme, H., Fischer, H., Ber. 75,
1310-11
(1942).
(3) Mackay, D. A. M., Evans Research & Development Corp., personal communication. (4) (5)
Meinwald, J., Chem. Ber. 88, 1889-91 ( 1 9 5 5 ) . Price, C. C., Bullitt, O. H., J. Org. Chem. 12, 2 3 8 - 4 8
(1947).
(6) Trambulo, Ghosh, Burrus, Bordy, PB 109891 (1953). RECEIVED for review June 6, 1957. Accepted June 19, 1957. Number I i n a series on reactions of ozone.
In OZONE CHEMISTRY AND TECHNOLOGY; Advances in Chemistry; American Chemical Society: Washington, DC, 1959.
