Formic Acid → 4-Bromo-1H-benzimidazole

Participants

Reaction Steps

A solution of 1,2-diamino-3-bromobenzene (2.00 g, 10.7 mmol) in formic acid (10 mL) was stirred at 100° C. for 1 hour. The pH of the mixture was adjusted to 14 by the addition of 4 M sodium hydroxide solution, precipitating the product as a solid. This was separated by filtration, washed with water and air-dried affording the product as an off-white solid. A further crop of equally pure material precipitated from the filtrate upon standing at room temperature for a few days. Total yield=1.98 g, 94%. 1H NMR (500 MHz, d6-DMSO): δ 12.83 (1H, s), 8.30 (1H, s), 7.58 (1H, d, J=7.9 Hz), 7.41 (1H, d, J=7.1 Hz), 7.14 (1H, t, J=7.8 Hz); m/z (ES+) 197, 199 [MH+].

Provenance & Evidence