3-Aminobenzoic Acid → 3-Hydrazinobenzoic acid hydrochloride

To a solution of m-aminobenzoic acid (200.0 g, 1.46 mmol) in concentrated HCl (200 mL) was added an aqueous solution (250 mL) of NaNO2 (102 g, 1.46 mmol) at 0° C. and the reaction mixture was stirred for 1 h. A solution of SnCl2.2H2O (662 g, 2.92 mmol) in concentrated HCl (2000 mL) was then added at 0° C. The reaction solution was stirred for an additional 2 h at RT. The precipitate was filtered and washed with ethanol and ether to give 3-hydrazino-benzoic acid hydrochloride as a white solid, which was used for the next reaction without further purification. 1H NMR (DMSO-d6): 10.85 (s, 3H), 8.46 (s, 1H), 7.53 (s, 1H), 7.48 (d, J=7.6 Hz, 1H), 7.37 (m, J=7.6 Hz, 1H), 7.21 (d, J=7.6 Hz, 1H).