23218-93-1

General procedure for the synthesis of methyl 3-amino-5-nitrobenzoate from methanol and 3-amino-5-nitrobenzoic acid: The esterification reaction was carried out by passing dry hydrogen chloride gas into a solution of methanol (160 ml) containing 5-amino-3-nitrobenzoic acid (18.5 g, 0.10 mol). After the solution was saturated, the reaction mixture was stirred at room temperature overnight. Subsequently, the mixture was concentrated to a crystalline residue. The residue was dissolved in dichloromethane and washed with 5% sodium bicarbonate solution until the pH of the aqueous phase reached 7-8. The organic phase was separated, dried over magnesium sulfate and evaporated to remove the solvent. The product 18.6 g was obtained in 94% yield.1H NMR (CDCl3) data: δ 8.21 (t, 1H, J=1.5Hz), 4.19 (br s, 2H), 3.96 (s, 3H).

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