To a mixture of 4-chloro-2-fluoronitrobenzene (1.00 g), silver sulfate (1.95 g), and concentrated sulfuric acid (5 ml), bromine (0.32 ml) was added under ice cooling, and the resulting mixture was stirred at 0 C. for 30 min, then at room temperature for 1 h. The reaction mixture was put into ice water and subjected to extraction with ether. The organic layer was washed with water, a saturated aqueous sodium hydrogen carbonate solution, and a saturated aqueous sodium chloride solution sequentially, dried with anhydrous sodium sulfate and concentrated under reduced pressure to give 1.38 g of 1-Bromo-2-chloro-4-fluoro-5-nitrobenzene (yield, 95%).
