General procedure for the synthesis of 4-bromo-5-nitrobenzene-1,2-diamine from N,N'-(4-bromo-5-nitro-1,2-phenylene)bis(4-methylbenzenesulfonamide): N,N'-(4-bromo-5-nitro-1,2-phenylene)bis(4-methylbenzenesulfonamide) (0.92 g. 1.71 mmol) was placed in a 10 mL round bottom flask. 90% sulfuric acid (2 mL) was added slowly and the reaction mixture was placed in an oil bath at 85°C with stirring and reflux for 2 hours. Upon completion of the reaction, the mixture was removed and cooled to room temperature and subsequently poured into 50 mL of water. The pH was adjusted to 9 with ammonia, at which point a red solid precipitated. After the mixture was cooled, filtration was carried out and the solid was washed twice with cold water. 4-Bromo-5-nitrobenzene-1,2-diamine (0.34 g, 86.8% yield) was finally obtained.
