A novel sodium iodide and ammonium molybdate co-catalytic system for the efficient synthesis of 2-benzimidazoles using hydrogen peroxide under ultrasound irradiation

• A H2O2/NaI/(NH4)6Mo7O24 system was first reported for synthesis of 2-benzimidazole.
• Ultrasound was demonstrated to be benefit for accelerating this reaction.
• The amounts of oxidant and catalyst are markedly reduced while keeping good yields.
• The reaction was performed efficiently in green conditions with high yields.

The reaction of aldehydes and o-phenylenediamine for the preparation of 2-benzimidazoles has been studied using hydrogen peroxide as an oxidant under ultrasound irradiation at room temperature in this paper. The combination of substoichiometric sodium iodide and ammonium molybdate as co-catalysts, together with using small amounts of hydrogen peroxide, makes this transformation very efficient and attractive under ultrasound. Thus, a mild, green and efficient method is established to carry out this reaction in high yield.