Preparation of 5-(2-halo-4-trifluoromethylphenoxy)-2-nitrobenzoic acid and salts and esters and amides

摘要

A process for preparing a substantially pure, isomer free 5-(2-halo-4-trifluoromethylphenoxy)-2-nitrobenzoic acid or its esters, salts and amides by the basic condensation of a 4-trifluoromethylphenol and a 1-chloro-3-substituted-4-nitrobenzene followed by halogenation. All known previous routes afforded, in addition to the desired product, a number of inactive isomers.