PROCESS FOR ESTERIFYING PHENOL-CONTAINING CARBOXYLIC ACIDS

摘要

Carboxylic acids containing phenol groups are esterified by means of (C1-C3)-alcohols in the presence of acid catalysts without the phenolic hydroxyl groups being esterified at the same time by continuously metering an excess of a water-containing (C1-C3)-alcohol into a boiling hot solution or suspension of the phenol-con-taining carboxylic acid and of the catalyst in a nonwater-miscible solvent (for example xylene) and at the same time distilling off a ternary solvent/alcohol/water mixture via a water separator, the metering rate being such that an aqueous bottom phase separates out in the receiving flask and the water content of the alcohol being so apportioned as not to breach the bottom limit of 0.1% or the upper limit of 1% (based on the contents of the reaction vessel) at any time in the course of the reaction. In this process, the esterification products are obtained free of major impurities and frequently can be used further without further purification.