Facile Sol-Gel Synthesis of Co3O4 Nanoparticles — An Efficient and Recyclable Catalyst for the Synthesis of 1,2-Disubstituted Benzimidazoles Under Solvent-Free Conditions

Abstract

High-surface-area Co3O4 nanoparticles have been prepared as a potential heterogeneous catalyst by the sol-gel method using starch as an inexpensive and a nontoxic starting material. Evidence showing that the cobalt precursor had been completely coverted into a pure crystalline Co3O4 phase with a cubic structure was obtained by X-ray diffraction analysis. The average particle size was estimated at 24 nm. The prepared catalyst was used in the synthesis of benzimidazoles. The developed methodology offers the advanvages of high yields (70–95%) and short reaction times (35–95 min) and avoids the use of toxic organic solvents. All of the reactions were carried out in the presence of Co3O4 nanoparticles (0.01 g) at 80°C under solvent-free conditions. The catalyst could be recovered and reused without any significant loss of activity.