Sol–gel synthesis of oxodiperoxo molybdenum-modified organic–inorganic materials for the catalytic epoxidation of cyclooctene

Hybrid organic–inorganic materials were synthesized by sol–gel copolymerization of the N,N-chelate ligand (3-triethoxysilylpropyl)[3-(2-pyridyl)-1-pyrazolyl]acetamide (1) and tetraethoxysilane (TEOS). Active solid oxidation catalysts can be obtained by introducing oxodiperoxo molybdenum species MoO(O2)2 into the hybrid sol–gel materials with a ligand-exchange reaction. The molybdenum-containing catalyst, prepared from a sol–gel precursor with relatively large pore volume and high specific surface area, showed a very high stability against leaching of the active species into the liquid phase during the epoxidation of cyclooctene with tert-butyl hydroperoxide (tBuOOH).