2-Amino-3-nitrobenzoic acid → 2,3-Diaminobenzoic acid

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Reaction Steps

Palladium on carbon catalyst (10% Pd, ˜200 mg) was added cautiously, as a slurry in methanol (10 ml), to a solution of 3-nitroanthranilic acid (2.44 g, 13 mmol) in methanol (120 ml), and the mixture was stirred under a hydrogen atmosphere for 2 hours until the absorption of gas ceased. The catalyst was removed by filtration through Celite, and the filtrate was evaporated to dryness under reduced pressure to afford the crude product. Purification by column chromatography on silica gel, with dichloromethane:methanol (4:1) as eluent, gave 2,3-diaminobenzoic acid as a red solid (1.34 g, 66%). vmax/cm−1 3433.73, 2882.02, 2602.30 and 1658.99; δH (d6-DMSO, 200 MHz) 5.8-7.4 (4H, br s, 2×NH2), 6.45 (1H, t, Ar-5H), 6.75 (1H, d, Ar-4H), 7.20 (1H, d, Ar-6H); δC (d6-DMSO) 110.31, 115.45, 118.33, 120.55, 135.03, 140.36, 170.68; m/z (EI) 152 (M+), 134, 106, 79.

Provenance & Evidence