γ-Alumina nanoparticles (γ-Al 2 O 3 NPs) have been successfully synthesized by electrochemical reduction method. The aqueous solution of tetrapropylammonium bromide was used as an electrolyte cum stabilizer. To prevent spontaneous agglomeration and control nanoparticles size various parameter such as current density, distance between electrodes and concentrations of electrolyte are optimized. γ-Al 2 O 3 NPs thus synthesized were characterized by sophisticated analytical techniques including X-ray diffraction, scanning electron microscopy, energy dispersive spectrophotometer and high-resolution transmission electron microscopy These synthesized γ-Al 2 O 3 NPs were tested used as a catalyst for one pot synthesis of tetraaryl imidazole derivatives from the cyclodehydration and condensation of benzil, aromatic aldehyde, anilines and ammonium acetate under solvent free condition. This method has various advantages like convenient work-up procedure, environmentally benign and less reaction times along with excellent yields. Easy availability, several times recyclability, very simple isolation and eco-friendliness were some attractive features of the nanocrystalline γ-Al 2 O 3 catalyst.

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