An Efficient One-Pot Synthesis of Benzimidazoles Using Magnetically Recoverable Catalyst Chromium Doped Nickel Copper Zinc Spinel Ferrite

Abstract

An efficient synthesis of benzimidazoles has been developed via one-pot two-component condensation reaction of o-phenylene diamine and aromatic aldehydes by using magnetic Cr 3+ doped Ni-Cu-Zn spinel ferrite as catalyst in ethanol. The products obtained with high yields in shorter reaction time. The Cr 3+ doped Ni-Cu-Zn spinel ferrites synthesized by sol gel auto combustion method and characterized by XRD, IR, TEM and VSM. The XRD patterns confirmed single phase of cubic spinel structure of catalyst. Lattice constant of catalyst decreased from 8.418 Å to 8.406 Å, while percentage porosity increases from 25.4 % to 27.7 % with increase in Cr 3+ content. The crystallite size decreased from 30.3 nm to 19.1 nm with increase in Cr 3+ content. Cr 3+ doped Ni-Cu-Zn spinel ferrites were soft magnetic materials. The catalyst can be robust and easily recoverable using external magnetic field and reused five times with almost the same catalytic activity. The proposed method is advantageous due to its small catalyst loading, short reaction time, magnetically catalyst recovery, catalyst reusability and better yields.