The general procedure for the synthesis of 3-aminobenzamide from 3-nitrobenzamide was as follows: 3-nitrobenzamide (33.3 g, 198.8 mmol) and FeCl3-6H2O (13.6 g, 50.4 mmol) were dissolved in ethanol (600 mL) and activated carbon (15 g) was added. The reaction mixture was heated to 60-65 °C in an oil bath. Hydrazine (30 mL, 85%, 510 mmol) was slowly added through a dropping funnel over 40 minutes. After addition, the reaction continued to be stirred at 60-65 °C for 5 hours. After completion of the reaction, the mixture was filtered under reduced pressure and the filtrate was concentrated. Dichloromethane (400 mL) was added to the concentrate, a precipitate was precipitated, the precipitate was removed by filtration and the filtrate was concentrated to give a white solid. The solid was further purified by recrystallization from ethyl acetate (EA) to give 3-aminobenzamide (21.0 g, 76% yield) as a final white solid. The product was characterized by 1H NMR (DMSO-d6, 400 MHz) and mass spectrometry (ESI+): 1H NMR δ 8.10 (s, 1H), 7.85-7.77 (m, 1H), 7.76 (d, J = 1.8Hz, 1H), 7.59-7.37 (m, 3H), 3.63 (s, 3H); MS (ESI+) m/z 137.1 [M + H]+.
