Formic Acid → 5-Trifluoromethyl-1H-benzimidazole

Participants

Reaction Steps

A mixture of 10 g (60 mmol) of 4-(trifluoromethyl)-1,2-phenylenediamine (Lancaster) and 50 mL of formic acid was refluxed for 2 h. Excess formic acid was then removed in vacuo. To the resultant concentrate was added 200 mL of water during which time a precipitate was discerned. This was filtered and discarded. The filtrate was concentrated in vacuo and redissolved in EtOAc. After repeated washing with saturated NaHCO3, the EtOAc solution was dried over MgSO4 and concentrated. The concentrate was put on a vacuum pump overnight. This resulted in 9.27 g (83%) of a yellow solid. 1H NMR (DMSO-d6) δ7.5 (d,1H, aromatic), 7.8 (d, 1H, aromatic), 8 (s, 1H, aromatic), 8.4 (s, 1H, CH), 12.8 (br s, 1H, NH).

Provenance & Evidence