Patent ID: 6372942
Filing Date: 2002-04-16
Classification: C07C

Abstract:
A process for hydroxycarbonylating pentenoic acid by reaction with water and carbon monoxide in the presence of a catalyst comprising at least rhodium and/or iridium and of an iodine-containing and/or bromine-containing promoter, comprising recycling in the reaction mixture at least part of the unreacted pentenoic acid, the catalyst and the promoter contained in the final reaction mixture, wherein, before recycling the unreacted pentenoic acid, the catalyst and the promoter, at least a part of the branched carboxylic diacids having 6 carbons produced by the hydroxycarbonylation reaction is separated and not recycled together with the unreacted pentenoic acid, catalyst and promoter in order to maintain the amount of said branched carboxylic diacids at a level less than or equal to 200 grams per kilogram of reaction mixture.