Nano- SnCl4⋅SiO2: An efficient catalyst for one-pot synthesis of 2,4,5-tri substituted imidazoles under solvent-free conditions

Nano- SnCl4⋅SiO2 as a solid Lewis acid has been synthesized by the reaction of nano- SiO2 and SnCl4. The structure characterization of this acid has been studied by FT-IR (ATR), XRD and SEM. Nano- SnCl4⋅SiO2 has been found to be an extremely efficient catalyst for the preparation of 2,4,5-trisubstituted imidazoles via three-component reactions of benzil, aldehydes and ammonium acetate under mild conditions. This process was simple and environmentally benign with high to excellent yields. Furthermore, the catalyst could be recovered conveniently and reused for at least three times.