The general procedure for the synthesis of 2,5-dibromo-1,4-benzenediol from hydroquinone was as follows: hydroquinone (20 g, 182 mmol) and 200 mL of glacial acetic acid were added to a 1 L three-necked flask fitted with a nitrogen inlet and a gas outlet under nitrogen protection. The flask was placed in an ice bath and the passage of nitrogen gas was initiated. Bromine (60.9 g, 381 mmol) was slowly added dropwise through a dropping funnel over 20 min. During the dropwise addition, a white solid gradually precipitated from the reaction mixture. After completion of the dropwise addition, the reaction mixture was continued to be stirred at room temperature for 12 hours. Upon completion of the reaction, the mixture was cooled in an ice bath, the white solid was collected by filtration and washed to neutrality with cold water. The final white solid product 2,5-dibromo-1,4-benzenediol (41.4 g, 85% yield) was obtained. The product was dried under vacuum and characterized by 1H NMR (300 MHz, CDCl3): δ 7.14 (2H, s), 5.2 (2H, br, s).
