Ammonia → Methyl 2,4-diamino-3-fluoro-5-nitrobenzoate

Participants

Reaction Steps

To a stirred solution of methyl 4-amino-2,3-difluoro-5-nitrobenzoate (4) (33.0 g, 142.15 mmol) in 1,4-dioxane (165 mL, 1.93 moles), in a 250 mL glass pressure vessel, was added an aqueous solution of ammonia (39 g, 711 mmol, 42.9 mL, 16.5 M). The vessel was then heated in an immersion bath at a bath temperature between 79 and 105° C., for 80 minutes, over which time the internal pressure ranged between 0.2 and 2.7 bar. The pressure was then released slowly and the mixture was treated with water (330 mL, 10 vol). The resultant suspension was stirred for 20 minutes and then filtered under vacuum, and the solid was washed with water (33 mL, 1 vol). The solid was sucked dry, then dried in a vacuum oven at 50° C. to provide methyl 2,4-diamino-3-fluoro-5-nitrobenzoate (5) (32.6 g, 92% yield) as a yellow solid. 1H NMR (500 MHz, d6 DMSO) δ 3.83, (3H, s, OMe), 7.20 (2H, br, NH2), 7.37 (2H, br, NH2), 8.47 (1H, s, Ar—H). 13C NMR (100 MHz, d6 DMSO) δ 52 (CH3), 101 (C), 122 (C), 126 (CH), 134 (C), 137 (C), 142 (C), 166 (C═O). νmax/cm−1 3474, 3358, 1697, 1633, 1528, 1435, 1317, 1285.

Provenance & Evidence