Synthesis and characterization of molybdenum complexes with bidentate Schiff base ligands within nanoreactors of MCM-41 as epoxidation catalysts

The mesoporous molecular sieve MCM-41 was covalently grafted with 3-aminopropyl trimethoxysilane to give aminopropyl modified MCM-41 (AmpMCM-41). Reaction of this material with furfural, pyrrolcarbaldehyde, 2-acetylpyrrol, 2-aminoacetophenone, salicylaldehyde and acetylacetone afforded the corresponding supported Schiff base ligands. Subsequent reaction with bis(acetylacetonato)dioxomolybdenum(VI) leads to various molybdenum complexes supported on MCM-41 through propyl chain spacer. Characterization of these materials was carried out with FT-IR, atomic absorption spectroscopy, powder X-ray diffraction (XRD) and BET nitrogen adsorption-desorption methods. The XRD and BET analyses revealed that textural properties of support were preserved during the grafting experiments. The resultant materials successfully catalyzed the epoxidation of cyclooctene, cyclohexene, 1-hexene and 1-octene with tert-butyl hydroperoxide (TBHP) to the corresponding epoxides with 98-100% selectivities. (c) 2006 Elsevier B.V. All rights reserved.