Studies On Epoxidation Of Aromatic Olefins

Epoxidation of aromatic olefins into epoxides which are important organic functional materials. The Fe3O4-supported cobalt (Co-Fe3O4) was prepared by conventional wet impregnation process, its structure was characterized by X-ray diffraction and X-ray photoelectron spectroscopy. The results indicated that 91.8% trans-stilbene conversion with 87.9S(25,3S)-2,3-diphenyloxirane yield was obtained under the optimal conditions:30wt% aqueous hydrogen peroxide (0.34 g,3.00 mmol), Co-Fe3O4 (0.10 g), acetonitrile (6.0 mL). Moreover, the high electron density or low steric hindrance of the C=C conjugated double bonds were favorable to the epoxidation. Based on mechanism researches, the active species of Co-Fe3O4 was cobalt compound which have high catalytic activity during the transformation and the Co-Fe3O4 nanocatalyst was recycled without loss of activity.The nitrotoluenes were condensed with aromatic aldehydes to afford the polynitrostilbenes by Knoevenagel reaction. In the presence of Lewis acid catalysts, polynitrostilbenes could be further epoxidized with high yield of new epoxy compounds using sodium chlorite. The structures of products were well verified by 1H and 13C NMR、IR、MS. When FeCl3·6H2O with n(polynitrostilbenes):n(NaClO2)= 1:3 was used to catalyze the reaction in acetonitrile/water at 55 ℃, the epoxide selectivity reached more than 80%. The single crystal of (25,35)-2-(3-nitrophenyl)-3-(2,4,6-trinitrophenyl)oxirane showed that inter-molecular hydrogen bonds was occurred between hydrogen atom and oxygen atom. The high yield of chlorinated product could be obtained when substrate has a plurality of strong electron-donating methoxy groups.