To a three-neck flask was added 13.7 g (0.1 mol) of 4-aminophenylboronic acid and 100 mL of trichloromethane. After thorough stirring, the reaction mixture was cooled to 5 °C and then 23.4 g (0.3 mol) of acetyl chloride was added slowly dropwise. After maintaining the reaction temperature at 5°C to complete the dropwise addition, the reaction system was warmed to 40°C and the reaction continued to be stirred for 3 hours. Upon completion of the reaction, 150 mL of water was added to the reaction mixture and the resulting solid product was washed with stirring. Subsequently, the solid was separated by filtration and washed with an appropriate amount of cold water. Finally, the resulting solid was dried in a vacuum drying oven to obtain 14 g of white or off-white solid powder 4-acetylaminophenylboronic acid in 78.2% yield.
