Design, preparation and characterization of urea-functionalized Fe3O4/SiO2 magnetic nanocatalyst and application for the one-pot multicomponent synthesis of substituted imidazole derivatives

• A new urea-functionalized silica-based magnetite hybrid core-shell structure was prepared.
• It showed excellent catalytic activity for the synthesis of substituted imidazoles.
• The heterogeneous nanocatalyst was simply separated from the reaction mixture.
• The catalyst was recycled several times without significant loss in catalytic activity.

Novel urea-functionalized silica-based magnetite hybrid core-shell nanoparticles were prepared and characterized by Fourier transform infrared spectroscopy (FT-IR), energy-dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), X-ray diffraction (XRD) and vibrating sample magnetometer (VSM) analyses. It was used as a highly efficient and recoverable heterogeneous nanocatalyst for the one-pot three-component condensation reaction between benzil or benzoin with various substituted aldehydes and ammonium acetate to afford the corresponding imidazoles under mild reaction conditions in high-to-quantitative yields. The catalyst was recycled at least five times without significant decrease in the catalytic activity.

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