GB647094A - Improvements in and relating to the manufacture of isovaleric acid - Google Patents

Abstract

Isovaleric acid is obtained by oxidizing methyl isobutyl ketone with an alkali metal hypobromite or hypochlorite, preferably the latter, with subsequent acidification of the aqueous portion of the reaction mixture. Bromoform or chloroform are also obtained. The hypohalite may be prepared in situ from the necessary halogen and aqueous alkali. The reaction takes place essentially as represented in the following equation in which X=Br or Cl. (CH3)2CH.CH2.CO.CH3+3NaOX= (CH3)2CH-CH2.COONa+CHX3+2NaOH. In examples: (1) commercial sodium hypochlorite (s.g. 1.25; 14-15 per cent available chlorine) is slowly added to methyl isobutyl ketone at 7-10 DEG C., stirred for five hours at this temperature and for two at room temperature when after standing overnight the lower layer containing chloroform and unchanged ketone is separated and the aqueous layer after concentration and acidification with dilute sulphuric acid deposits the required acid which is collected and purified by distillation; (2) the above reaction is effected first at 45 DEG C., then after addition of excess sodium hypochlorite at about 60 DEG C., the reaction mixture being treated as before except that excess hypochlorite is removed by addition of sodium bisulphite to the aqueous layer; (3) methyl isobutyl ketone is suspended in aqueous caustic soda solution at 0 DEG C., chlorine passed until the requisite quantity has been absorbed at 0-3 DEG C. the reaction mixture then stirred for two hours and allowed to reach room temperature when after standing overnight it is treated p as before except that the aqueous layer is heated in the water bath to remove chloroform and excess ketone and acidified without concentration; (4) is conducted in a similar manner to (1), sodium hypobromite being used at 10 DEG C.; and (5) is similar to (3) using bromine in place of chlorine at - 1 DEG C. to \sR1 DEG C.