General procedure for the synthesis of 5-bromo-1,3-benzenediamine from 3,5-dinitrobromobenzene: To a methanol:water (V/V: 50 mL/50 mL) solution of 1-bromo-3,5-dinitrobenzene (10 g, 40 mmol) was added ammonium chloride (17.33 g, 323.9 mmol) and iron powder (11.31 g, 202.5 mmol). The reaction mixture was stirred and refluxed at 95 °C overnight. Upon completion of the reaction, it was filtered through a diatomaceous earth pad to remove the iron powder and the filtrate was concentrated by rotary evaporation to remove methanol. The remaining aqueous phase was extracted with dichloromethane (3 x 50 mL), the organic layers were combined, washed sequentially with water and saturated saline, and dried over anhydrous sodium sulfate. After filtration, the filtrate was concentrated under reduced pressure to obtain the crude product. The crude product was purified by silica gel column chromatography using appropriate eluents to afford 5-bromo-1,3-benzenediamine (7.01 g, 92% yield) as a yellow solid. The structure of the product was confirmed by 1H NMR (400 MHz, CDCl3): δ 6.25 (d, 2H, J=2.0 Hz), 5.90 (t, 1H, J=2.0 Hz), 3.60 (s, 4H).
