Formic Acid → 7-Bromo-5-nitro-1H-benzimidazole

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Reaction Steps

To a 100 mL round bottomed flask was added 3-bromo-5-nitrobenzene-1,2-diamine (5 g, 21.55 mmol) and formic acid (3.25 mL, 86 mmol) in Toluene (10 mL). The solution was heated to reflux overnight. The product precipitated and was triturated with toluene, diluted with water and adjusted to ph 9 with 6N NaOH. The solid was filtered, washed with water and placed in a vacuum oven overnight to yield 4-bromo-6-nitro-1H-benzo[d]imidazole (5.02 g, 20.74 mmol, 96% yield) as a brown solid. 1H NMR (400 MHz, DMSO-d6) δ ppm 8.16 (s, 1H) 8.29 (d, J=2.02 Hz, 1H) 8.51 (d, J=2.02 Hz, 1H) 8.66 (s, 1H); LC/MS: MS (ES+) m/e 243 [M+H]+.

Provenance & Evidence