p-Toluenesulfonic acid → 2-(2-Methylphenyl)-5-nitrobenzimidazole

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Reaction Steps

2-Methylbenzoyl chloride (4.1 g, 0.027 mol) is added to 2-amino-4-nitroaniline (4 g, 0.025 mol) in toluene (100 ml), and the mixture is refluxed for 24 hours. para-Toluenesulfonic acid (1.0 g) is added, the mixture is refluxed for 36 hours and concentrated, and the residue is taken up in ethyl acetate. The solution is washed with NaHCO3 and then with water. The resulting solution is dried and concentrated, and the solid obtained is recrystallized from isopropyl ether. Yield: 3.1 g (48%); Rf (7/3 toluene/ethyl acetate): 0.58; 1H-NMR (d6-DMSO): 8.5 (d, 1H); 8.1 (dd, 1H); 7.7 (m, 2H); 7.4 (m, 3H); 2.6 (s, 3H).

Provenance & Evidence