Hydrochloric Acid → 3-Bromo-2-chloro-4,5-difluoro-1-nitrobenzene

To a mixture of anhydrous cupric chloride (3.1 g) and 2-bromo-3,4-difluoro-6-nitroaniline (4.6 g) in anhydrous acetonitrile (30 ml) was added t-butylnitrite (2.8 g) dropwise at 51° to 56° C. during 5 minutes. After stirring for 8 minutes at the same temperature, the reaction mixture was poured into chilled 10% diluted hydrochloric acid (30 ml) and extracted with benzene. The organic layer was washed with diluted hydrochloric acid and with water successively, dried over anhydrous sodium sulfate and concentrated. The resulting residue was purified by silica gel chromatography eluting with dichloromethane-n-hexane (1:5) to give the title compound (4.0 g).