General procedure for preparation of 2,4-dihydroxybenzamide. It was prepared by the addition of 1.69 g (0.10 mol) methyl 2,4-dihydroxybenzoate in 10 mL of ammonia (pro analysis, 25% in water). The reaction mixture was stirred for 24 hours at room temperature. The excess ammonia and methanol formed during the reaction were removed under reduced pressure. Upon addition of 10 mL of water, the product was extracted by ether. Ether extracts were collected and washed with water, and after separation, the ether layer was dried over anhydrous sodium sulfate and evaporated under reduced pressure to give 2,4-dihydroxy benzamide. Crude products were purified by column chromatography using ethyl acetate as a mobile phase[1].
[1] Milena Jadrijevi?-Mladar Takac, Drazen Viki? Topi?. “FT-IR and NMR spectroscopic studies of salicylic acid derivatives. II. Comparison of 2-hydroxy- and 2,4- and 2,5-dihydroxy derivatives.” Acta Pharmaceutica 54 3 (2004): 177–91.
