The general procedure for the synthesis of 1-methyl-1H-imidazole-2-carboxylic acid from 1-methyl-1H-imidazole-2-carboxaldehyde is as follows: first, 1-methyl-1H-imidazole-2-carboxaldehyde was prepared by referring to the method described in literature [23]. Subsequently, the synthetic procedure for Im2COOH (1b) was followed, and the reaction yield was up to quantitative levels after removal of water under high vacuum (without diethyl ether/water washing). Note that heating may cause decarboxylation to occur. Product yield: 100%. Melting point range is 99-101 °C. NMR hydrogen spectrum (400MHz, D2O): δH 7.42, 7.39 (2H, single peak, imidazolium cyclic-H), 4.08 ppm (3H, single peak, N-CH3); NMR carbon spectrum (400MHz, D2O): δC 158.67, 139.68, 125.83, 118.46, 36.73 ppm. infrared spectrum ( KBr press method): ν 3347 (medium intensity), 3119 (medium intensity), 2663 (weak), 1641 (strong), 1683 (medium intensity), 1507 (strong), 1449 (medium intensity), 1388 (strong), 1338 (strong), 1285 (strong), 1173 (medium intensity), 1123 (strong), 961 (medium intensity), 910 (medium), 776 (strong), 685 (strong) cm-1. Calculated values from elemental analysis (C5H8N2O3, molecular weight 144.12): C, 41.67%; H, 5.59%; N, 19.44%. Measured values: C, 41.28%; H, 5.23%; N, 19.12%.
