2-Nitrobenzaldehyde → HCID 178423936, compound

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Reaction Steps

2,3-Diaminotoluene (12.2 g, 0.1 mol) was dissolved in the mixture of MeOH/H2O (500 mL, v/v=1:1), acetic acid (10 mL) was added to the stirring mixture. 2-Nitrobenzaldehyde (21.1 g, 0.14 mol) in MeOH (250 mL) and Cu(OAc)2.H2O (28.0 g, 0.14 mmol) in water (250 mL) were added subsequentially to the mixture. It was then heated to reflux for 3 h under vigously stirring, a pale yellow precipitate was formed. Filtered while it was hot and washed with water to afford a gray-yellow solid. Redissolved the precipitate in EtOH (600 mL) and HCl (75 mL, Conc.), a solution of Na2.S9 H2O (48.0 g, 0.2 mol) in water (300 mL) were added. The mixture was heated to reflux for 1 h resulted in a black slurry. Cooled down to room temperature, it was filtered through a pad of celite to remove of CuS. The filtrate was neutralized with ammonium hydroxide to PH=8-9. Concentration using a rotary evaporator, a green-yellow precipitate was formed. After filtration and dried in vaccum oven, the crude product was purified by column chromatography on silica gel using a mixture of hexane/ethyl acetate (1:1) as the eluent to give 4-methyl-2-(2-nitrophenyl)-benzimidazole (18 g, 72%) as a yellow needle crystal. Rf=0.21 (hexane/ethyl acetate=1:1); 1H NMR (250 MHz, CDCl3) δ 2.60 (s, 3H), 7.10 (d, J=8.2 Hz, 1H), 7.20 (t, J=7.9 Hz, 1H), 7.41 (bs, 1H), 7.52-7.66(m, 2H), 7.89-7.97 (m, 2H), 10.41 (bs, 1H); HRMS: Calcd for C14H11N3O2 253.0851, found 253.0854.

Provenance & Evidence