Process for the preparation of the methyl or ethyl ester of p-nitrobenzoic acid

摘要

By means of two-stage esterification of p-nitrobenzoic acid with methanol or ethanol, removal of the water of reaction and the excess alcohol by distillation after the first esterification stage, subsequent esterification in the second esterification stage with alcohol which is low in water or anhydrous, and return of the mother liquor from the crystallisation of the esters to the first esterification stage, the esters are obtained in substantially increased yield and purity.