GB668998A - Improvements in and relating to esterification - Google Patents

Abstract

Esters of good colour are made by reacting polyvinyl and polyallyl alcohols with a carboxylic acid or anhydride thereof while bubbling sulphur dioxide through the reaction mixture.ALSO:Esters of good colour are made by reacting an organic compound containing at least one esterifiable hydroxy group with a carboxylic acid or anhydride thereof while bubbling sulphur dioxide through the reaction mixture. Esterifiable compounds may be mono- or poly-hydric, aliphatic, alicyclic or aromatic and may contain such inert groups as halogen, alkoxy and carbalkoxy and representative of many specified are: methanol, cyclohexanol, methallyl alcohol, 2 : 8-dodecadienol, phenol, benzyl alcohol, glycerol distearate, glycol, 2 : 4 : 6-heptanetriol and resorcinol. Preferred are ethylenically unsaturated alcohols with at least one ethylenic linkage preferably not more than four carbon atoms removed from the hydroxy group and many of such compounds are specified. A particular class of hydroxy compounds contains an ethylenic linkage in the beta, gamma position relative to a terminal hydroxy group, many of such compounds being specified including allyl alcohol, 2 : 4-hexadienetriol-1 : 3 : 6, 2-butenediol-1 : 4-monoallyl ether, 2-butenediol monoacrylate, chloroallyl alcohol, 3-cyclohexyl-2-propen-1-ol and 2-phenyl-2-buten-1-ol. Any carboxylic acid may be used, preferred being aliphatic, alicyclic or aromatic mono- or polycarboxylic acids. They may contain inert substituents such as halogen, sulphate, nitrate, ether and ester groups. Many acids are specified, representative being acetic, arachidic, crotonic, cyclobutanecarboxylic, benzoic, succinic, fumaric, tricarballylic, trimellitic, tetrachlorophthalic, gamma-carbethoxy brassylic acids, monobutyl adipate and monochloroallyl terephthalate. Polycarboxylic acids are of particular use. Mixtures of acids and/or hydroxy compounds may be used. A list of esters obtainable is given, representative being butyl acetate, diallyl phthalate, allyl amyl succinate, 2-butenyl caproate, trichloro-allyl hemimellitate and allyl benzoate. Preferably conventional esterification catalysts are used and many are specified. Preferably one to five equivalents of hydroxy compound as compared with acid are used. Temperatures of about 70-150 DEG C., particularly 80-100 DEG C., are preferred, and pressures may be varied. Generally a saturated solution of sulphur dioxide should be maintained. Diluents and polymerization inhibitors may be used and many of conventional type are specified. Peroxides are desirably absent. Water and aldehydic impurities are preferably removed from the reaction mixture as soon as formed. In examples: (1) diallyl; (2) dimethallyl; (5) octyl; and (7) butyl, ethyl, 2-butenyl and glyceryl diacetyl phthalates; (3) diallyl succinate; (4) chloroallyl propionate; and (6) diallyl maleate are made by conventional catalysed azeotropic methods whilst sulphur dioxide is bubbled through the reaction mixture.