Synthesis of peroxy-functionalized magnetic mesoporous silica for epoxidation of vinyl acetate.

Highlights • Magnetic mesoporous silica nanocomposites with peroxy groups were obtained. • These heterogeneous oxidizing agents were used in epoxidation of vinyl acetate. • Magnetic response facilitated the separation and recycle of the materials. Abstract Peroxy-functionalized magnetic mesoporous silica (MMS-PA) composites containing magnetic nanoparticles (MNPs) and peroxy acids were synthesized to be used as an easily reusable heterogeneous oxidant for the epoxidation of alkenes. The presence of peroxy acid functional groups on the composites was confirmed by Fourier transform infrared spectroscopy (FTIR). Transmission electron microscope (TEM) of the MMS-PA composites revealed the irregular structure of porous silica attached with the MNPs. The surface area of the MMS-PA was calculated to be 1089 m2 g−1, which is significantly lower than that of the starting mesoporous silica. As measured using vibrating sample magnetometer (VSM), MMS-PA exhibited saturation magnetization of 0.12 emu/g, indicating that the heterogeneous oxidant could respond to an external magnet. The oxidizing activity of the synthesized MMS-PA composites was investigated using vinyl acetate as a model substrate; the yields of the corresponding epoxide products were measured using nuclear magnetic resonance (NMR) spectroscopy. At room temperature, the freshly prepared MMS-PA gave 52% yield of the product, and the yield decreased only slightly to 47% for the recycled MMS-PA obtained by reactivating the recovered MMS-PA with concentrated H 2 O 2 in acidic medium. [ABSTRACT FROM AUTHOR]