It Synthesis of 2-phenyl benzimidazole derivatives by oxidative condensation reaction with o-phenylenediamine (1.05 mmol), substituted benzaldehyde (1 mmol), catalyst cobalt (II) acetylacetoneand solvent CH3OH stirring at room temperature for 4 hours. Solubility experiments showed that the cobalt (II) acetylacetone is miscible with methanol and relatively readily soluble in polar solvents such as ethanol, and they are partially immiscible with no-polar solvents such as ethyl acetate, and tetrahydrofuran. The efficiency of the reaction was mainly affected by the amount of the catalyst. As can be seen from Table 1, the optimal amount of cobalt (II) acetylacetone was 0.05 mmol (entry 2). The isolated yield of 2-phenylbenzimidazole decreases with the increase of cobalt (II) acetylacetone from 0.05 mmol to 0.5 mmol.
