Synthesis
The general procedure for the synthesis of 2-amino-6-nitrophenol from 2,6-dinitrophenol was as follows: a suspension of 2,6-dinitrophenol (5.0 g, 27 mmol), ammonium hydroxide (3 ml) and ammonium chloride (14 g) was mixed with 30 ml of water. To the mixture was added an aqueous solution of sodium sulfide hydrate nine (24.19 g, 100 mmol), followed by heating the reaction system to 70°C and stirring for 2 hours. After completion of the reaction, the mixture was cooled to room temperature, acidified to pH 3.2 with 2N HCl and filtered to collect the brown precipitate. The filtrate was extracted with chloroform (6 x 75 ml) and after combining the organic extract with the precipitate, the solvent was removed by vacuum evaporation to afford the dark brown solid product 2-amino-6-nitrophenol (2.5 g, 60% yield). The structure of the product was confirmed by 1H NMR (CDCl3): δ 4.09 (s, 2H), 6.78 (t, 1H, J = 8.2 Hz), 6.95 (d, 1H, J = 7.8 Hz), 7.47 (d, 1H, J = 8.6 Hz), 10.73 (s, 3H).
References
[1] Patent: WO2005/28445, 2005, A2. Location in patent: Page/Page column 38
[2] Bioorganic and Medicinal Chemistry Letters, 2014, vol. 24, # 15, p. 3521 - 3525
[3] Journal of Medicinal Chemistry, 2004, vol. 47, # 6, p. 1319 - 1321
[4] Patent: WO2005/44793, 2005, A2. Location in patent: Page/Page column 135
[5] Patent: US2014/309208, 2014, A1. Location in patent: Paragraph 0237; 0238
