IMPROVED METHOD OF PRODUCING UNSATURATED CARBOXYLIC ACID ANHYDRIDES Russian patent published in 2012 - IPC C07C51/56 C07C51/54 C07C57/04 C07C51/573 

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method of producing unsaturated carboxylic anhydrides of general formula I, in which R is an unsaturated organic residue having 2-12 carbon atoms by re-anhydridising an aliphatic carboxylic anhydride through reaction with a carboxylic acid of general formula II, in which R is as defined above, in an apparatus consisting of a reaction region and a rectification column, wherein a) the reactants are fed into the reaction region in stoichiometric ratios, b) the carboxylic acid formed as a by-product is removed from the reaction mixture, c) the carboxylic anhydride of the formula I is subsequently distilled off, d) the unconverted reactants are recycled into the reaction region, e) the reaction region contains a heterogeneous catalyst and f) one or more polymerisation inhibitors are added.

EFFECT: improvement lies in that stoichiometric excess of one of the reactants is avoided, formation of secondary components is prevented and complete conversion of reactants is achieved.

6 cl, 1 dwg, 2 ex