Hydrochloric Acid → 4-Bromo-alpha-chloro-3-methylbenzaldoxime

In a solution of 82.0 g of 4-bromo-3-methylbenzaldoxime in 450 mL of tetrahydrofuran, 120.0 g of concentrated hydrochloric acid was added dropwise under cooling with ice and with stirring over 45 minutes. Then, 220 mL of 8% sodium hypochlorite aqueous solution was added dropwise over 75 minutes carefully so that the temperature of the reaction mixture would not exceed 5° C. After the completion of the addition dropwise, it was continued to stir at a temperature of 10° C. or less for further 90 minutes. After the completion of the reaction, the reaction mixture was blown with nitrogen gas for 45 minutes, then precipitated insoluble material was filtered off, tetrahydrofuran was distilled off under reduced pressure. The residual aqueous solution was extracted with 240.0 g of ethyl acetate, and the organic phase was washed with water (240 mL×2). The insoluble material was filtered off, the solvent was distilled off under reduced pressure to obtain 93.5 g of the aimed product as pale yellow crystal.