Step 2: Synthesis of 8-bromo-7-hydroxyquinoline
A solution of bromine (22.9 mL, 0.444 mol) in acetic acid (120 mL) was slowly added dropwise to a stirred mixture of 7-hydroxyquinoline (59.0 g, 0.406 mol) in acetic acid (120 mL) and dichloromethane (240 mL), and the internal temperature of the reaction system was controlled to be at 0-5 °C. The resulting suspension was continued to be stirred at 0-5 °C for 2 h. Upon completion of the reaction, it was diluted with ethyl acetate (100 mL) and filtered. The solid product was collected, washed with ethyl acetate (2 x 20 mL) and subsequently dried under vacuum to afford 8-bromo-7-hydroxyquinoline (65 g, 76% yield).
