Acetone → 1-Bromo-3-(4-chlorophenyl)propan-2-one

To a solution of 1-(4-chlorophenyl)propan-2-one (25.0 g, 148 mmol) in acetic acid (37.9 mL) was added 48% aqueous HBr (19.0 mL, 168 mmol). A solution of bromine (16.3 mL, 316 mmol) in acetic acid (63.2 mL) was then added over 10 minutes and the resulting solution was stirred for 4 hours at room temperature. Acetone (190 mL) was added and the resulting solution was stirred at room temperature for 3 days. The reaction was concentrated in vacuo and the residue was taken up in DCM (300 mL) and brine (100 mL). The layers were separated and the aqueous layer was extracted with DCM (100 mL). The combined organic layers were dried over MgSO4, filtered, and concentrated in vacuo. The residue was purified by silica gel chromatography (ethyl acetate/hexanes=0/100→15/85) to give 25.4 grams of the title compound as a dark gray solid (69% yield). 1H NMR (400 MHz, CDCl3) δ: 7.34-7.31 (m, 2H), 7.18-7.15 (m, 2H), 3.94 (s, 2H), 3.91 (2, 2H).