3970-37-4

3970-35-2

3970-37-4

General procedure for the synthesis of 1-bromo-2-chloro-3-nitrobenzene from 2-chloro-3-nitrobenzoic acid: 2-chloro-3-nitrobenzoic acid (15 g, 74.4 mmol) was dissolved in 350 mL of carbon tetrachloride under nitrogen protection and red mercuric oxide (24.3 g, 111.62 mmol) was added. The mixture was heated to 87°C under light conditions to reflux and bromine (5.75 mL, 111.6 mmol) was added slowly and dropwise. After the dropwise addition was completed, the reaction was continued at reflux for 3 h, followed by cooling to room temperature. The reaction mixture was quenched with saturated aqueous sodium bicarbonate solution, stirred for 10 min and filtered through a diatomaceous earth pad. The filter cake was further washed with dichloromethane. The organic layer was separated, washed sequentially with water and brine and dried over anhydrous sodium sulfate. The solvent was removed by concentration under reduced pressure to give 11.55 g of 1-bromo-2-chloro-3-nitrobenzene in 67% yield. The product was detected by 400 MHz 1H NMR (CDCl3) with chemical shifts of δ 7.84 (d, 1H), 7.71 (d, 1H), 7.27 (dd, 1H); and mass spectra (M + 1) of 235, 237, 239.