A mixture of 2-[4-(4-chlorophenyl)benzyloxy]-3,3,3-trifluoro-2-trifluoromethylpropionic acid (3.0 g.), thionyl chloride (3.0 ml.), dimethylformamide (0.16 g.) and benzene (10 ml.) is heated under reflux until the solution becomes turbid (ca. 10 minutes). The mixture is evaporated in vacuo, benzene (10 ml.) is added and the evaporation is repeated. Light petroleum (10 ml., b.p. 40°-60° C.) is added to the residue, and the solution is separated from insoluble oils and evaporated to give 2-[4-(4-chlorophenyl)benzyloxy]-3,3,3-trifluoro-2-trifluoromethylpropionyl chloride (3.07 g.), m.p. 30°-35° C.
