Formic Acid → 4-Methylbenzimidazole

Participants

Reaction Steps

A solution of 3-methylbenzene-1,2-diamine (500 mg, 4.1 mmol) in formic acid (4.5 mL, 120 mmol) was irradiated in a microwave oven for 15 min at 135° C. The reaction mixture was cooled to ambient temperature and the formic acid was removed under reduced pressure. The residue was dissolved in ethyl acetate (20 mL) and extracted with saturated aqueous NaHCO3 (2×10 mL), water (10 mL) and brine (10 mL). The organic phase was dried over anhydrous Na2SO4 and the solvent was removed in vacuum yielding 4-methyl-1H-benzoimidazole (519 mg, 96%). Calculated for C8H8N2 m/z: 132.07, found 133.13 [M+H]+. 1H NMR (400 MHz, DMSO-d6) δ ppm 2.50 (s, 3H), 6.96 (m, 1H), 7.06 (m, 1H), 7.38 (d, J=7.6 Hz, 1H), 8.15 (s, 1H), 12.41 (s, 1H).

Provenance & Evidence