Synthesis
General procedure for the synthesis of 3-nitro-5-bromobenzene-1,2-diamine from 2,6-dinitro-4-bromoaniline: a mixture of 4-bromo-2,6-dinitroaniline (5.5 g, 21.2 mmol) and ammonium sulfide (10.5 mL, 21.2 mmol) in ethanol (150 mL) was heated and reacted for 1 hr at 90 °C. Thin layer chromatography (TLC) monitoring showed incomplete consumption of the feedstock. Ammonium sulfide (10.5 mL, 21.2 mmol) was added and the reaction was continued with stirring at 90 °C for 1 hour. Upon completion of the reaction, the mixture was concentrated and purified by silica gel column chromatography (eluent: petroleum ether/dichloromethane = 1:1) to afford the target compound 3-nitro-5-bromobenzene-1,2-diamine (2.5 g, 51% yield) as a red solid. Liquid chromatography-mass spectrometry (LCMS) analysis results: m/z 230, 232 ([M+H]+).
References
[1] Patent: WO2016/168682, 2016, A2. Location in patent: Paragraph 0288
[2] Patent: US2012/88767, 2012, A1. Location in patent: Page/Page column 13; 15; 19
[3] Analytical Chemistry, 1983, vol. 55, # 6, p. 963 - 965
