41011-01-2

99-02-5

41011-01-2

Molecular sieve-dried 3-chloroacetophenone (154.6 g, 1 mol) was added to a four-necked flask with anhydrous methanol (310 mL) under nitrogen protection. Bromine (158.2 g, 0.99 mol) was slowly added dropwise under continuous stirring in the temperature range of 30 °C to 45 °C. The dropwise addition was controlled to be completed within 1 h. The reaction was carried out in a controlled manner. After the dropwise addition was completed, the reaction mixture was kept at the same temperature and stirring was continued for 10 minutes. Subsequently, water (160 g) was added and the reaction solution was cooled to -10°C to promote crystal precipitation. The precipitate was collected by filtration to give 250 g of crude product. The crude product was dissolved in heptane (750 g), washed twice sequentially with water (200 g) and the organic phase was dried with anhydrous magnesium sulfate. The desiccant was removed by filtration, and the filtrate was concentrated to give 212.5 g of 2-bromo-3-chloroacetophenone in 91.0% yield, and no impurities were detected.