Method for producing ester plasticizers

A process for preparing ester plasticizers by reacting dicarboxylic or polycarboxylic acids or their anhydrides with alcohols in the presence of a titanium-, zirconium- or tin-containing catalyst, which comprises allowing a mixture of acid or acid anhydride and alcohol to react first at from 100 to 160° C. while removing any water formed, completing the reaction by addition of the catalyst and increasing the temperature to about 250° C., neutralizing the reaction mixture with an aqueous alkali metal hydroxide or alkaline earth metal hydroxide solution, then separating off the excess alcohol and drying and filtering the remaining crude ester.