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u ' N i T E D , S T A T E S

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P A T E N T o F F i c i :mass;PRODUCTION DP 3811538 OFMETHAOBYYLIC ACIDJohn William Croom Crawford, A r d r o s a n , Scotland, assignor to Imperial C h e m i c a l Industriesl i m i t e d , a c o r p o r a t i o n o f B r i t a i nv N o A p p l i c a t i o n S e p t e m b e r 1 4 , 1 0 3 4 ,S e r i a l N o . 1 4 4 , 0 0 1 .3 1 , 1 9 s :

m o d i ? c a t i o n s in t h e p r o d u c t i o n of esters ofm e t h a c r y l i c a c i d by t h e i n t e r a c t i o n o f acetone Icyanhydrin, a mineral a c i d , a n d a n a l c o h o l . 5 According t o t h i s invention e s t e r s o f man.a c r y l i c a c i d ' a r e p r o d u c e d b y t r e a t i n g a c e t o n ecyanhydrin with concentrated o r fuming s u lp h u r i c a c i d a t r a i s e d temperature and s u b s eq u e n t l y h e a t i n g the r e a c t i o n mixture with a1 0 monoliydric a l c o h o l . In a p r e f e r r e d form o f t h i s

' process the reaction m i x t u r e of a ce tone cyanhydrin a n d s u l p h u r i c a c i d i s maintained a t ate mperature o f about 1 4 0 C . for at l e a s t 1 hourb e f o r e adding t h e a l c o h o l .

1 5 A c c or d i n g to the present invention an im. - p r o v e d or modi?ed process c o m p r i s e s h e a t i n g t h er e a c t i o n m i x t u r e , a f t e r t h e t r e a t m e n t o f t h ea c e t o n e cyanhydrin and s u l p h u r i c a c i d a t a r a i s e dt e m p e r a t u r e h a s b e e n s u b s t a n t i a l l y c o m p l e t e ,9' w i t h a q u a n t i t y o f water p r e f e r a b l y amounting t o not more than f o u r m o l e c u l a r p r o p o r t i o n s f o re v e r y m o l e c u l a r p r o p o r ti o n o f a c e t o n e cyanhy

I My e s t r e s u l t s have been obtained when a b o u t t w o - m o l e c u l a r w e i g h t s of w a ter' are a d d e d2 6 - for e a c h : m o l e c u l a r w e i g h t o f a c e t o n e c y a n h y d r i n .I T h e water may be a d d e d t o g e t h e r with the a pp r o p r i a t e a l c o h o l f o r t h e e s t e r d e s i r e d , a n d t h emixture h e a t e d . I ' ? n d , h o w e v e r , t h a t i t i s a dv antageous to a d d t h e w ater a n d t o heat to r e8 0 ?uxing t e m p e r a t u r e f o r some t i m e ' b e f o r e addingthe a l c o h o l . The a l c o h o l i s then addedand t h eh e a t i n g c o n t i n u e d f o r a f u r t h e r p e r i o d t o a f f e c t ]t h e . e s t e r i ? c a t i o n . By t h i s means t h e t o t a l timerequired f o r the process i s appreciably l e s s , par

8 5 t i c u l a r l y wi th t h e . lower a l c o h o l s , than i f the wat e r and a l c o h o l were a d d e d t o g e t h e r an d t h e m i x t u r e s i m p l y heated o r e? u x i n g t emper at ur e.In the p r e f e r r e d form o f t h e i n v e n t i o n t h e ,r e a c t i o n b e t w e e n t h e a c e t o n e c y a n h y d r i n andsulphuric acid or o l e u m i s c a r r i e d out i n thepre s e n c e 0 1 ' an an t ipo lymer izat io n catalyst a t.t e m p e r a t u r e s of a b o u t 8 0 , t o 90 C. The'main-, t e n a n c e o f a s u i t a b l e temperature range may becontrolled by the r a t e of m i x i ng of the reactantsa n d , i f : r e q u i r e d , s u i t a b l e c o o l i n g . A f t e r m i x i n gt h e : r e a c t a n t s , the temperature o f t h e m a s s i smaintained between 1 0 0 and 1 4 0 C . p r e f e r a b l y

; approaching t h e l a t t e r t e m p e r a t u r e , f o r aperiodof time; c . g . about one hour. The w ater i s then u n d e r re?uxing c o n d i t i o n s f o r a f u r t h e r p e r i o d ,e . g . about three hours; a f t e r w h i c h the a l c o h o l i sa d d e d and t h e r e ? u x i n g c o n t i n u e d f o r a n o t h e r2 t o 3 h o u r s . I f a lower b o i l i n g a l c o ho l g i s used5 5 I ?nd t h a t i t i s p r e f e r a b l e t o c o o l t h e r e a c t i o n

7 10 Claims. 01200-100)T h i s invention relates to improvements or'

added and t h e h e a t i n g o f t h e m i x t u r e c o n t i n u e d .

In Great B r i t a i n O c t o b e r

m i x t u r e b e f o r e a d d i n g t h e a l c o h o l t h e r e b y a v o i di n g e x c e s s i v e r e ? u x i n g immediatelyon i t s a d d ition. A l t e r n a t i v e l y , t h e water and t h e a l c o h o l m a y

be a d d e d s imul taneous ly t o the mixture; i n t h i sc a s e a l s o h e a t i n g f o l l o w s under re?uxing c o n d it i o n s , f o r example f o r a p e r i o d o f , 1 5 h o u r s i n t h ecase o f methyl a l c o h o l .

In both forms o f t h e p r o c e s s t h e a m o u n t o f a lQ c o h o l i s s u i t a b l y a b o u t t w o m o l e c u l a r p r o p o rt i o n s f o r e a c h ' molecular p r o p o r t i o n o f a c e t o n ec y a n h y d r i n . ,A f t e r h e a t i n g with t h e a l c o h o l , t h e r e a c t i o n

product may be i s o l a t e d b y known me thods; fore x a m p l e , by d i r e c t s e p a r a t i o n a f t e r p o u r i n g t h ereactionmixture i n t o water o r v b r i n e o r d i s t i l l i n geither d i r e c t l y or in a current o f steam.The i n v e n t i o n i s i l l u s t r a t e d by t h e f o l l o w i n ge x a m p l e s , i n which a l l p a r t s a r e p a r t s by w e i g h t .E x a m p l e 1-The c r u d e a c e t o n e c y a n h y d r i n i sp r e p a r e d by a l l o w i n g o n e m o l e c u l a r p r o p o r t i o no f . a c e t o n e t o r e a c t with l . 0 3 , p r o p o r t i o n o f hydrogen c y an i d e , i n t h e p r e s e n c e o f c a u s t i c potasha s c a t a l y s t , a n d s t a b i l i z e d a f t e r completion o fthe reaction b y addition of a l i g h t excess of s u lphuri c a c i d over that n e c e s s a r y } t o n e u t r a l i z et h e p o t a s h c a t a l y s t . E s t i m a t i o n shows t h e p r o du c t tocontain 8 5% a c e t o n e c y a n h y d r i n . This i sd i s t i l l e d i n v a c u o , the d i s t i l l a t e c o l l e c t e d beingpractically-100% a ce tone c y anhy drin.

850 parts o f the s o prepared pure acetonecyanhydrln a r e run with good mechanical a g i t at i o n i n t o 1 5 0 0 gms. o f 98 s u l p h u r i c a c i d con-'t a i n i n g 1 5 p a r t s o f s u l p h u r ? o w e r s . The t e mp e r a t u r e o f t h e r e a c t i o n mixture i s maintained byc o o l i n g a t ' 7 0 - 8 0 u n t i l a l l t h e cyanhydrin hasbeen a d d e d , w hen t h e temperature o f t h e r e a c t i o nmixture i s r a i s e d t o 1 4 0 f o r 1 hour. Whilst heati n g through t h e temperature r e g i o n o f a b o u t 1 0 0 ,foaming i s i n c l i n e d t o s t a r t , and a g i t a t i o n i s ,t h e r e f o r e , s t o p p e d a t t h i s s t a g e u n t i l g a s e v o l u t i o nh a s s u b s i d e d , when s t i r r i n g i s recommended.A f t e r h e a t i n g a t 1 4 0 , t h e t e m p e r a t u r e o f t h e r ea c t i o n mixture i s l o w e r e d a t 6 5 , and 1 0 p a r t s o ftannic a c i d a n d a mixture o f 3 6 0 p a r t s o f waterand 640 gms. of me t h y l alcohol are ad d ed. Ther e a c t i o n mixture i s re?uxed f o r 1 8 h o u r s , a n d

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poured with s t i r r i n g i n t o 3000 parts o f strongb r i n e . The whole i s ? l t e r e d t o remove s u l p h u rwhich h i n d e r s s e p a r a t i o n , a n d t h e e s t e r l a y e rremoved. I t i s g i v e n a f u r t h e r w a s h with b r i n e ( 1 0 0 0 p a r ts ) t o remove m e t h y l a l c o h o l a n d i a t t h i s s t a g e weighs 7 3 2 p a r t s . Drying o v e r c a l c i u mc h l o r i d e , 2 0 p a r t s , and d i s t i l l a t i o n g i v e s 6 0 2 p a r t s

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3 1 3 2 . f .o f pure e s t e r , p l u s 1 1 8 p a r t s or a mixture o r e s t e ra n d methacrylic a c i d w h i ch may be convertedi n t o pure e s t e r by i ' u r t h e r treatment wit h methyla l c o h o l i n the known m a n n er o f preparing e s t e r s .Example 2 . - 8 5 0 p a r t s o f c r u d e 87% a c e t o n ecyanhydrin a r e - m i x e d w i t h s t i r r i n g i n t o a s u spension o f 4 p a r t s o f ?owers o f sulphur i n 1 5 0 0p a r t s o r oleum o i l 5 t r e e s u l p h u r i c anhydridec o n t e n t . The t e m p e r a t u r e i s k e p t l o w , 1 0 0 , byc o o l i n g d u r i n g t h e a d d i t i o n , and t h e r e a f t e r r a i s e dt o 1 3 0 - 1 3 5 f o r a p e r i o d o f 1 hour, w i t h continueds t i r r i n g . At t h e end o f t h i s p e r i o d , t h e temperat u r e o f t h e mixture i s l o w e r e d t o about 7 0 ' , a n d1 0 p a r t s o f t a n n i c a c i d , f o l l o w e d by a mixtu re of3 6 0 p a r t s o f w a t e r and 4 0 p a r t s i . methyl a l c o h o l ,are added. This mixture i s re?uxed f o r 13 hoursand poured i n t o t w i c e i t s volume o f c o n c e n t r a t e db r i n e , w i t h g o o d s t i r r i n g . The s e p a r a t e d l a y e r0 1 ' e s t e r i s rem ove d a n d w a she d again wi th a ne q u a l volume o f b r i n e t o remove un ch an gedmethyl a l c o h o l . The e s t e r , s e p a r a t e d from t h i swash, weighs 7 9 2 p a r t s . I t i s d r i e d o v e r 2 0 p a r t so f c a l c i u m c h l o r i d e . A f t e r d r y i n g , t h e e s t e rw e i g h s 7 7 5 p a rt s e q u i v a l e n t t o 77.7% y i e l d on t h ea c e t o n e used t o produce t h e cyanhydrin. I t may f u r t h e r b e p u r i ? e d , f o r i n s t a n c e by f r a c t i o n a l d i st i l l a t i o n under a s l i g h t v a c u u m , w h e n 683 p a r t so f pure e s t e r a r e o b t a i n e d , wi th 8 0 parts o f r e s id u e , c o n s i s t i n g o f a mixture o f e s t e r a n d m e tha c r y l i c a c i d w h i ch may e c onverted i n t o e s t e r bynown ethods. ' Example 3 . 8 5 0 p a r t s o f c r u d e 95% a c e t o n ecyanhydrin were added t o 1 5 0 0 p a r ts o i 100% s u lp h u r i c a c i d c o n t a i n i n g i n s u s p e n s i o n , a s : a n a n t ip o l y m e r i z a t i o n c a t a l y s t , 4 p a r t s o f copper b r o n z e

powder (90% C u , 10% Z n ) . The r e a c t a n t s werem i x e d i n a n enamelled j a c k e t e d v e s s e l with gooda g i t a t i o n a n d maintenance i . t h e temperature a t' 8 0 - 8 5 C . To maintain t h i s temperature d u r i n gt h e a d d i t i o n o f t h e acetone cyanhydrin i t w a sn e c e s s a r y t o ?ow c o o l i n g water through theJ a c k e t . On c o m p l e t i o n o f the a d d i t i o n o f thecyanhydrin the temperature w a s r a i s e d t o 1 3 0 C . an d maintained about t h i s ?gure f o r one h o u r .3 6 0 p a r t s of wat er were then a dded g r a d u a l l ya n d t h e mixture heated under re?uxing condit i o n s f o r 3 hours during wh i ch p e r i o d t h e t e mperature o f t h e r e a c t i o n mixture w a s ' about 1 2 5 C .The temperature w a s lowered s o m e w h a t a n d6 4 0 p a rt s o f methyl a l c o h o l g r a d u a l l y a d d e d ,a v o i d i n g e x c e s s i v e r e ? u x i n g . This mixture w a sthen b o i l e d under re?ux f o r 2 hours mea s uredfrom the c o m m e n c e m e n t o f the a l c o h o l a d d i t i o n ,t h e temperature o f t h e r e a c t i o n mixture beingabout 8 0 C .After t h i s heating the r e a c t i o n mixture w a sa g i t a t e d w i t h 3 0 0 0 p a r t s o f s t r o n g b r i n e , t h e e s t e rl a y e r then s e p a r a t e d a n d a g a i n washed with b r i n et o y i e l d a c r u d e p r o d u c t c o n t a i n i n g 6 9 6 p a r t sm e t h y l m e t h a c r y l a t e and 4 7 p a r t s m e t h a c r y l i ca c i d . A u r i ? e d m e t h y l m e t h a c r y l a t e b o i l i n g a t6 1 . 5 C . , u n d e r 2 0 0 mm. mercury pressure, wasobtained by f r a c t i o n a l d i s t i l l a t i o n through a c o lumn u n der 200 mm. r e s s u r e . The methacrylica c i d w a s returned t o the process f o r e s t e r i ? c a t i o ni n a l a t e r batch.Ex a m p l e 4 . - . 8 5 0 p a r t s by weight o f crude 95cyanhydrin were a d d e d t o 1 5 0 0 p a rt s 0 1 . 100% s u lp h u r i c a c i d c o n t a i n i n g 4 p a r t s o f c o p p e r b r o n z e ,heated 1 hour a t 1 3 0 C . _ a n d b o i l e d with 3 6 0 p a r t so f water a s d e s c r i b e d i n E x a m p l e 3 .The r e a c t i o n product w a s c o o l e d t o 8 0 C . 1 2 0 0p a r t s o f i s o p r o p y l a l c o h o l were a d d e d . with s t i rr i n g , a n d the s t i r r e d mixture heated t o re?uxingtemperature (around 8 8 ) f o r 2 h o u r s . I t w a s

2 , 0 4 9 , 4 5 8then run i n t o 3 0 0 0 p a r t s o f a g i t a t e d water a n d t h ee s t e r l a y e r removed and w a shed with 1 0 0 0 p a r t so f w a t e r . The p a r t i a l l y p u r i ? e d e s t e r s e p a r a t e dfrom t h i s w a s h i n g t r e a t m e n t w e i g h e d 1 0 2 0 p a r t sa n d v a n a l y z e d 6 6 . 1 % o f i s o p r o p y l m e t h a c r y l a t eand 1 1 . 6 % o f f r e e m e t h a c r y l i c a c i d .In o r d e r t o f u r t h e r p u r i f y the e s t e r , i t w a s a g it a t e d with 6 5 p a r t s o f 5 o l u t i o n o f c a u s t i c s o d a ,s e p a r a t e d and w a shed t w i c e with w a t e r , thend r i e d o v e r 3 0 p a r t s o f ca l cium c h l o r i d e , 1 - 2 p a r t so f t a n n i c a c i d b e i n g a dded t o p r e v e n t p o l y m e r i z at i o n a n d ?nally d i s t i l l e d under reduced p r e s s u r e ,using a f r a c t i o n a t i n g column. The s t e r w a s c o ll e c t e d a t 7 7 . 5 - 8 2 . 5 C . a t a pressure o r 184 mm.Example 5.--850 parts of crude acetone c y a n

hydrin o f 88.5% p u r i t y were m i x e d i n t o a s t i r r e ds u s p e n s i o n o f 4 p a r t s o f s u l p h u r i n 1 5 0 0 p a r t s o fs u l p h u r i c a c i d c o n t a i n i n g 5 . 9 % o f f r e e s u l p h u r i ca n h y d r i d e , a t a temperature o f between 7 0 ? and8 0 C . an d t h e r e a f t e r t h e mixture heated f o r 4hours t o a temperature o f 1 1 0 - 1 1 5 , c o o l e d t o 6 0 ,and a mixture o f 3 6 0 p a rt s o f w a t e r , 6 4 0 p a r t so f methyl a l c o h o l a n d 1 0 p a r t s o f t a n n i c a c i da d d e d . A f t e r b o i l i n g under re?ux f o r 1 5 h o u r s ,

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the mixture w a s run i n t o 3000 parts o f brine a n d 2 5a g i t a t e d . The e s t e r l a y e r w a s then removed andw a she d with a f u r t h e r 1 0 0 0 p a r t s o f b r i n e . A f t e rd r y i n g with 2 0 p a r t s o f ca l cium c h l o r i d e i t weighed4 1 0 p a r t s and n d i s t i l l a t i o n t h e r e were obtained8 5 8 p a r t s o f methyl methacrylate a n d a r e s i d u e o f 3 0crude methacrylic ac id we ighing 48 p a r t s .Example 6.850 p a r t s o f c r u d e 95% a c e t o n ecyanhydrin were a d d e d w i th s t i r r i n g t o a mixture0 1 ' 4 p a r t s o f copper bronze (90% c o p p e r , 10%z i n c ) and 1 5 0 0 p a r t s o f 100% s u l p h u r i c a c i d , a ta temperature o f 8 0 C . The product w a s heated t o a temperature o f 1 3 0 C . f o r 1 hour a n dthen t r e a t e d wi th 3 6 0 p a r t s o f water a n d b o i l e df o r 3 hours under a re?ux condenser ( t h e t e mp e r a t u r e of t h e b o i l i n g l i q u i d b e i n g around1 2 8 ) , w i t h a g i t a t i o n . 6 4 0 p a r t s o f m e t h y l a lcohol were a d d e d a n d the mixture b o i l e d underr e f l u x f o r 2 hours, run i n t o brine a n d worked u pa s i n E x a m p l e 2 . The w a s h e d e s t e r weighed7 7 3 p a r t s and c o n t a i n e d 90.0% methyl m e th ac r y l a t e a n d 5 . 1 8 parts o f methacrylic a c i d . .Example 7. 2 5 5 parts of recti?ed acetone cyanhydrin were add ed w i th a g i t a t i o n t o a suspen

s i o n o f 3 p a r t s o f sulphur i n 4 5 0 p a r t s o r v98%s u l p h u r i c a c i d , a t a temperature o f ' 1 0 - 8 0 C .The mixture'was h e a t e d , s t i l l with s t i r r i n g , t oa temperature o f 1 4 0 C . f o r 1 hour c o o l e d t o1 0 0 C . a n d a mixture o f 1 0 8 p a rt s o f water a n d4 4 4 p a r t s o f b u t y l a l c o h o l a d d e d . This m i x t u r ew a s re?uxed f o r 3 h o u r s , the temperature o f theb o i l i n g l i q u i d r e a c h i n g 1 2 0 C . and then a f t e rc o o l i n g , poured i n t o 1 0 0 0 p a r t s o f w a t e r . Thee s t e r l a y e r , weighing 6 2 2 p a r t s , w a s s e p a r a t e d ,w a s h e d wi th d i l u t e a l k a l i , d r i e d o v e r ca l ciumc h l o r i d e , - and t r a c t i o n a l l y d i s t i l l e d t o s e p a r a t eb u t y l a l c o h o l and b u t y l m e t h a c r y l a t e . The l a t t e rw a s c o l l e c t e d between 8 1 a n d 8 6 C . atapressureo 50 m m._of mercury, the bulk o f the f r a c t i o np a s s i n g overat 8 5 - 8 6 C . I t weighed 2 4 8 p a r t s .Example 8.450 p a r t s o f s u l p h u r i c a c i d cont a i n i n g 3 p a r t s o f s u l p h u r ?owers i n s u s p e n s i o nwere w e l l a g i t a t e d and 2 5 5 p a r t s o f crude 88%a c e t o n e cyanhydrin run i n , the temperature o ft h e m i x t u r e b e i n g k e p t a t 8 0 C . by c o o l i n g andby r e g u l a t i o n o f t h e r a t e o f a d d i t i o n o r the cya n h y d r i n . The mixture w a s h e a t e d , s t i l l with

, s t i r r i n g , f o r 1 hour t o 1 4 0 C . , c o o l e d o f f t o about1 0 0 C . and t r e a t e d with 3 p a r t s o f t a n n i c a c i d ,1 0 8 pa r t s o f w a t e r , and 4 4 4 p a r t s o f normal b u t y l

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2 , 0 4 2 , 4 5 8a l c o h o l . Heat was then a p p l i e d u n t i l t h e m i xt u r e b o i l e d a n d b o i l i n g continued under a re?uxc o n d e n s e r f o r 3 h o u r s , t h e temperature o f t h el i q u i d b e i n g about 1 2 0 C . The product w a s a llowed t o c o o l o f f a n d run i n t o 1 0 0 0 p a r t s o f _ w at e r . An pper l a y e r o f crude e s t e r weighing 6 2 2p a r t s w a s removed, w a s h e d w i th d i l u t e a l k a l ia n d d r i e d over calcium c h l o r i d e .c r u d e e s t e r w a s s e p a r a t e d from accompanyingnormal b u t y l a l c o h o l by f r a c t i o n a l d i s t i l l a t i o nunder r e d u c e d p r e s s u r e , 2 4 8 p a r t s o f normalb u t y l m e t h a c r y l a t e , b o i l i n g p o i n t 81 - 8 6 C . / 5 0mm. being o b t a i n e d .Example 9 . 3 4 0 p a r t s by w e i g h t o f c r u d e 95%acetone c y a n h y d r i n w e r e mixed w i t h a g i t a t i o ni n t o a s u s p e n s i o n o f 2 p a r t s o f copper bronze( 9 0 : 1 0 : c o p p e r z z i n c ) i n 4 5 0 p a r t s o f 100% s u lphuric a c i d a t a temperature o f 8 0 - C . T h eproduct w a s heated t o 1 3 0 C; f o r 1 ' hour wi tha g i t a t i o n , and c o o l e d t o 1 1 0 C . 1 0 8 p a r t s o fwa ter were then a d de d a n d the mixture b o i l e dunder re?ux f o r 2 h o u r s , t h e temperature o f themixture being about 1 3 0 . I t w a s c o o l e d t o 8 0 ,4 4 4 p a r t s o f i s o b u t y l a l c o h o l a dded a n d againb o i l e d und er re?ux f o r 2 1 / 2 h o u r s , t h e ?nal t e mperature o f the l i q u i d being 1 0 7 . The cooled

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product w a s run i n t o 1 0 0 0 p a r t s o f w a t e r , a g it a t e d and t h e e s t e r l a y e r r e m o v e d . I t weighed6 8 6 p a r t s and c o n t a i n e d 60.8% o f i s o b u t y l m e t ha c r y l a t e a n d 3.9% o f methacrylic a c i d a n d w a sp u r i ? e d , a f t e r w a s h i n g w i t h a l k a l i , b y f r a c t i o n a ldistillation. . _Example 10.850 p a r t s o f c r u d e 95% a c e t o n e,cyanhydrin were m i x e d a t a temperature o f 8 0 i n t o 1 5 0 0 p a rt s o f s u l p h u r i c a c i d c o n t a i n i n g 0.4%o f s u l p h u r i c a n h y d r i d e , i n which were suspended 4 p a r t s o f copper bronze powder. The m i xture w a s heate d for 1 hour to a te mperature of1 3 0 , 360 p a r t s o f water were added, a n d the m i xture w a s then b o i l e d u n der a re?u x condenser for2 h o u r s . At the c o n c l u s i o n o f t h i s period the r ea c t i o n mixture w a s cooled t o 1 1 6 , a n d 1800p a r t s o f g l y c o l monoethyl e t h e r c o n t a i n i n g 1 0p a r t s o f t a n n i c a c i d were a d d e d s l o w l y . Whenthe addition w a s complete, the mixture w a sw a r m e d t o 1 0 0 - 1 1 0 f o r 4 h o u r s , w i t h . a g i t a t i o n . The reaction m a s s w a s then cooled a n dt r e a t e d with 1 5 0 0 p a r t s o f w a t e r , a n d t h e e s t e rw a s s e p a r a t e d . A f t e r t wo f u r t h e r washingswith 1 0 0 0 p a r ts o f w a t e r , t h e c r u d e e s t e r weighed8 2 8 p a r t s and c o n t a i n e d 82.3% o f beta-ethoxye t h y l m e t h a c r y l a t e and 7.9% o f f r e e m e t h a c r y l i ca c i d . For f u r t h e r p u r i ? c a t i o n t h e e s t e r w a s d i st i l l e d under r e d u c e d pressure. _

I claim:1 . In a p r o c e s s f o r the preparation o f e s t e r so f m e t h a c r y l i c a c i d by the i n t e r a c t i o n o f a c etone cyanhydrin, a n inorganic acid a n d an a lc o h o l ; t h e s t e p s which comprise t r e a t i n g t h e r ea c t i o n p r o d u c t o b t a i n e d from a c e t o n e cyanhyd r i n and s u l p h u r i c a c i d with a q u a n t i t y o f w a t e r ,

The dried

n o t e x c e e d i n g f o u r m o l e c u l a r p r o p o r t i o n s b a s e don the a c e t o n e cyanhydrin p r e s e n t , and ? n a l l yheating i n p r e s e n c e o f t h e s a i d monohydric a lc o h o l .2 . Process o f claim 1 , i n whi ch t h e r e a c t i o nmixture i s heated under re?ux f o r a t l e a s t 1hour a f t e r t h e a d d i t i o n o f water a n d b e f o r e thea d d i t i o n o f t h e monohydric a l c o h o l .3 . P r o c e s s o f claim 1 i n w h i ch two molecularproportions o f wa ter a r e u s e d .

4 . Process o f claim 1 i n whi ch t h e r e a c t i o n i sc a r r i e d out i n presence o f a n antipolymerizationc a t a l y s t .5 . In a p r o c e s s f o r the preparation o f e s t e r so f m e t h a c r y l i c a c i d by t h e i n t e r a c t i o n of a c e t o n e

cyanhydrin, a n i n o r g a n i c a c i d a n d a n a l c o h o l ,t h e s t e p s which c o m p r i s e t r e a t i n g t h e r e a c t i o nproduct o b t a i n e d from a c e t o n e cyanhydrin a n ds u l f u r i c a c i d w i th a quantity o f w a t e r , not exceeding f o u r molecular p r o p o r t i o n s based on thea c e t o n e cyanhydrin p r e s e n t b e f o r e t h e a d d i t i o no f monohydric a l c o h o l , and ? n a l l y h e a t i n g i nthe presence of the mo n o h y d r i c alcohol.6 . In a process f o r the preparation o f e s t e r so f methacrylic a c i d by t h e i n t e r a c t i o n of acetonecyanhydrin, a n inorganic a c i d a n d a n a l c o h o l ,t h e s t e p s which c o m p r i s e t r e a t i n g t h e r e a c t i o nproduct o b t a i n e d from a c e t o n e cyanhydrin a n ds u l f u r i c a c i d wi th a quantity o f w a t e r , not exceeding four molecular p r o p o r t i o n s based on t h e

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i )a cetone eyanhydrin present during the addition o f t h e monohydric a l c o h o l . _ and ? n a l l y heating.i n the presence o f t h e monohydric a l c o h o l .

' 7 . In a p r o c e s s f o r the preparation o f e s t e r so f methacrylic a c i d by t h e i n t e r a c t i o n o f a c e t o n ecyanhydrin, a n i n o r g a n i c a c i d a n d a n a l c o h o l ,t h e s t e p s which c o m p r i s e re?uxing t h e r e a c t i o nproduct o b t a i n e d from a c e t o n e cyanhydrin ands u l f u r i c acid w i th a quantity o f w a t e r , not ex

' cee ding four mole cu l ar proportions b a s e d on theacetone cyanhydrin p r e s e n t f o r a t l e a s t one houra f t e r t h e a d d i t i o n o f the water a n d b e f o r e t h ea d d i t i o n o f t h e monohydric a l c o h o l , and ? n a l l yheating i n the p r e s e n c e o f t h e monohydric a lc o h o l .8 . Process o f claim 7 i n w h i c h the r e a c t i o n i scarried out i n the presence o f a n antipolymeriz a t i o n c a t a l y s t .9 . Process o f claim 7 i n w h i c h t h e r e a c t i o n i scarried out i n the presence o f t w o molecularp r o p o r t i o n s o f w a t e r .1 0 . In a p r o c e s s f o r the preparation o f methylmethacrylate by t h e i n t e r a c t i o n o f a c e t o n e cya n h y d r i n , s u l f u r i c a c i d a n d - m e t h a n o l , t h e s t e p swhi ch c o m p r i s e t r e a t i n g t h e r e a c t i o n p r o d u c tobtained from a c e t o n e cyanhydrin a n d s u l f u r i ca c i d w i t h a p p r o x i m a t e l y t w o m o l e c u l a r p r o p o rt i o n s o f water re?uxing t h e r e s u l t i n g mixturea n d ?nally heating i n t h e p r e s e n c e o f methanol.

JOHN W . C . CRAWFORD.

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4 CERTIFICATE OF CORRECTION.Patent No. 2,042,458. _ June. _ _ , 1936.

J O H N W I L L I A M C R O O M C R A W F O R D .I t i s hereby certified that error appears i n t h e printed specification o f

t h e above numbered p a t e n t requiring correction a s f o l l o w s ; P a g e 1 s e c o n d -column, line 4 5 , for the word recommended read recommenced; and line 4 5 ,for at read to; a n d t h a t the s a i d Let t ers P a t en t sh o u l d be read-wi th these(corrections therein that the same m a y c o n f o rm to the record of the case inthe Patent Office. _

Signed and sealed t h i s 25th day of August, A . D . 1 9 5 6 .

Leslie Frazer(Seal) Acti ng Commiss ioner of Pa tents,