p-Toluenesulfonic acid monohydrate → 5-Bromo-1-methyl-2-phenyl-1H-benzo[d]imidazole

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Reaction Steps

7.8 g (26 mmol) of 4′-bromo-N-methyl-2′-amino-benzanilide were suspended into 50 mL of xylene. Then, 1.5 g (7.7 mmol) of p-toluenesulfonic acid monohydrate was added, and the whole was refluxed under heating for 7 hours. After the completion of the reaction, the resultant was filtered. The resultant solid was dissolved into methylene chloride, washed with 10-mass % K2CO3 and a saturated sodium chloride solution, and dried with magnesium sulfate. After that, the solvent was distilled off under reduced pressure. The filtrate was washed with 10-mass % K2CO3 and a saturated sodium chloride solution, and dried with magnesium sulfate. After that, the solvent was distilled off under reduced pressure. The resultant two residues were coalesced, and the resultant was purified by means of silica gel column chromatography to obtain 6.5 g of 5-bromo-1-methyl-2-phenyl-1H-benzimidazole as a white solid (89% yield).

Provenance & Evidence