Alkene and thioether oxidations with H2O2 over Ti-containing mesoporous mesophase catalysts

Well-organized Ti-containing mesoporous mesophase materials (Ti-MMM) have been synthesized by hydrothermal synthesis using C16H33N(CH3)(3)Br and characterized by elemental analysis, IR, DRS-UV, XRD, and N-2 adsorption. Catalytic properties of these materials in alkene and thioether oxidations with aqueous H2O2 in CH3CN have been studied and compared with those of the Ti-containing hexagonal mesoporous silica (Ti-HMS). The Ti-MMM catalysts with the Si/Ti atomic ratio varying in the range of 49-124 showed the highest catalytic activities in alkene oxidation. Both the structure of a silicate matrix and a degree of isolation of titanium ions in it are crucial factors determining catalytic activity of Ti-MMM. For thioether oxidation, the structural perfection of Ti-MMM catalysts is less important. No leaching of titanium ions occurs during both reactions. The oxidation process proved to be truly heterogeneous. (C) 2000 Elsevier Science B.V. All rights reserved.