Patent ID: 6916950

Claim:
A process for preparing carboxylic esters, which comprises: in a batch process, reacting polycarboxylic acids or their anhydrides with alcohols in a liquid medium with the concomitant removal of water formed by the esterification reaction by azeotropic distillation together with the alcohol in the medium, wherein the volume amount of liquid azeotrope mixture of water and alcohol removed from the reaction medium by azeotropic distillation is entirely replaced with the alcohol, whereby the volume amount of water azeotropically removed during the batch process at least corresponds to the volume amount of water formed by the reaction of the starting quantity of polycarboxylic acids or anhydrides thereof and the alcohol down to a reduced amount of polycarboxylic acids or anhydrides thereof in the terminal stages of the ester forming reaction indicated by an acid number value of 0.5 mg KOH/g.