Functionalized Magnetite/Silica Nanostructures in Knoevenagel Condensation

A simple procedure for the synthesis of functionalized magnetic iron oxide supported sulfonic acid (Fe3O4@SiO2-Pr-NH2-SO2CH3) is reported. The product was characterized using Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), vibrating sample magnetometer (VSM), thermogravimetric analysis (TGA), transmission electron microscopy (TEM) and energy-dispersive analysis of X-ray (EDAX). SEM analysis exhibits homogeneous dispersion of spherical nanoparticles for Fe3O4@SiO2-Pr-NH2-SO2CH3. The as-prepared catalyst was applied in Knoevenagel condensation of benzaldehyde derivatives with ethyl cyanoacetate in solvent-free condition at 80 degrees C. The products were obtained in high-to-excellent yields at short times. The catalyst can be extracted and reused in the next reaction cycle by using an external magnet. Graphic abstract The synthesis of heterogeneous basic magnetic catalyst is developed which is applied as efficient catalyst in Knoevenagel condensation of benzaldehyde derivatives with ethyl cyanoacetate. The coating of Fe3O4 magnetic NPs with silica followed by functionalization with organic and inorganic compounds is very effective and valuable process. The as-prepared catalyst exhibited interesting catalytic activity in solvent-free conditions. [GRAPHICS] .