A Mild and Rapid Synthesis of 2-aryl Benzimidazoles by using SO42-/ZrO2-TiO2 as a Heterogeneous Catalyst

Herein, we have reported an efficient synthesis of 2-aryl benzimidazoles by reacting o-phenylenediamines and substituting aromatic aldehydes using SO42-/ZrO2-TiO2 as a heterogeneous catalyst. This methodology is straightforward to obtain 2-aryl benzimidazoles with good to excellent yields. It has been performed in ethanol as a green solvent. The reported protocol has some advantages such as a safe and reusable heterogeneous catalyst, without any need for column chromatography to obtain desired products. The catalyst can be recovered for up to five catalytic cycles without significant loss in the catalytic activity.