General procedure for the synthesis of 4-bromo-1,2-bis(bromomethyl)benzene from 4-bromo-1,2-xylene: To a 1000 mL round-bottomed flask were added 4-bromo-o xylene (0.0811 mol, 15.0 g), N-bromosuccinimide (NBS, 0.0426 mol, 7.580 g), 2,2'-azobisisisobutyronitrile (AIBN. 0.00405 mol, 0.6650 g) and 500 mL of carbon tetrachloride (CCl4). The reaction mixture was heated to reflux for 1 hour. Subsequently, NBS and AIBN were added in four additional portions.After completion of the reaction, the reaction mixture was filtered while hot to remove the precipitate and the filtrate was concentrated. The crude product was purified by hexane crystallization to give white crystals (23 g, 93% yield). The structure of the product was confirmed by 1H NMR (300 MHz, CDCl3): δ 7.53 (d, 1H, ArH, J = 2.0 Hz), 7.44 (dd, 1H, ArH, J = 8.1 Hz, J = 2.0 Hz), 7.24 (d, 1H, ArH, J = 8.1 Hz), 4.60 (d, 4H, CH2, J = 4.2 Hz).
