General procedure for the synthesis of 4-methyl-1H-imidazole-2-carboxylic acid from ethyl 4-methyl-1H-imidazole-2-carboxylate: ethyl 4-methyl-1H-imidazole-2-carboxylate (77.0 g, 0.5 mol) was dissolved in anhydrous ethanol (600 mL) at room temperature, and 250 mL of 40% aqueous sodium hydroxide was subsequently added. The reaction mixture was heated to 50 °C and maintained at this temperature for the reaction. Upon completion of the reaction, it was cooled to room temperature, neutralized and acidified with 37% concentrated hydrochloric acid to pH=6. The solvent was removed by distillation under reduced pressure and the resulting residue was purified by column chromatography using dichloromethane/methanol (10:1, v/v) as eluent to give the final 4-methyl-1H-imidazole-2-carboxylic acid (60.2 g, 96% yield) as a white solid.
