1-Methylimidazole → ethyl 1-methyl-1H-imidazole-2-carboxylate

Participants

Reaction Conditions

Reaction Steps

N-methylimidazole (320 g, 3.9 mol) was combined with 2 L acetonitrile and 1 L triethylamine in a 12 L flask equipped with a mechanical stirrer and the solution cooled to −20° C. Ethyl chloroformate (1000 g, 9.2 mol) was added with stirring, keeping the temperature between −20° C. and 25° C. The reaction was allowed to slowly warm to room temperature and stir for 36 h. Precipitated triethylamine hydrochloride was removed by filtration and the solution concentrated in vacuo at 65° C. The resulting oil was purified by distillation under reduced pressure (2 torr, 102° C.) to provide Ethyl 1-methylimidazole-2-carboxylate as a white solid (360 g, 82% yield). TLC (7:2 benzene/ethyl acetate v/v) Rf 0.2; 1H NMR (DMSO-d6) δ7.44 (d, 1H, J=2.8 Hz), 7.04 (d, 1H, J=2.8 Hz), 4.26 (q, 2H, J=3.5 Hz), 3.91 (s, 3H), 1.26 (t, 3H, J=3.5 Hz); 13C NMR (DMSO-d6) δ159.3, 129.1, 127.7, 61.0, 36.0, 14.5; IR(KBr) 3403, 3111, 2983, 1713, 1480, 1422, 1262, 1134, 1052, 922, 782, 666; FABMS m/e 155.083 (M+H 155.083 calc. for C7H11N2O2).

Provenance & Evidence