General procedure for the synthesis of 1,4-dibromo-2,5-bis(bromomethyl)benzene from 2,5-dibromo-1,4-dimethylbenzene: 2,5-dibromo-p-xylene (26.4 g, 0.1 mol) and N-bromosuccinimide (NBS, 39 g, 0.22 mol) were suspended in carbon tetrachloride (300 mL), and benzoyl peroxide (0.6 g) was added as the initiator. Prior to the start of the reaction, a nitrogen stream was passed through the bubble for 5 min to exclude oxygen. Subsequently, the reaction mixture was heated and refluxed in an oil bath at 100 °C for 2 hours. Upon completion of the reaction, ethanol (200 mL) was added to precipitate the product and the solid was collected by filtration. The solid was washed with ethanol (50 mL) to remove residual reactants and by-products and finally dried under vacuum to afford 1,4-dibromo-2,5-bis(bromomethyl)benzene as a white solid (13.36 g, 31.6% yield). The structure of the product was confirmed by 1H-NMR (500 MHz, CDCl3): δ 7.68 (s, 2H, aryl ring hydrogen), 4.50 (s, 4H, bromomethyl hydrogen).
