Methanesulfonic Acid → 2-(2-Bromophenyl)-1H-benzimidazole

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Reaction Steps

To a flask were added 80 g methanesulfonic acid and 8 g phosphorus pentoxide and the mixture was heated to 60 C under nitrogen until the solids had completely dissolved. To this solution was added 2.7 g 1,2-phenylene diamine and 5.0 g 2-bromobenzoic acid and the mixture was heated to 100 C for 30 minutes. The mixture was poured onto 300 ml ice water and basified with the addition of small portions of sodium carbonate. Following filtration of the solid and washing with water, the crude product was dissolved in 85 ml hot ethanol, filtered and 9 ml of water was added. After cooling to 5 C, the product was filtered and washed with 50% ethanol and dried, giving 3.85 g off-white solid.

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