Investigation of catalytic activities of new heterogeneous molybdenum catalysts in epoxidation of olefins

The mesoporous molecular sieve MCM-41 was covalently grafted with 3-aminopropyl trimethoxysilane and acetyl acetone (acac) successively to give modified MCM-41 (acacAmpMCM-41). Reaction of this material with amino acids, e.g. alanine, phenyl alanine, leucine, isoleucine, histidine and valine afforded the corresponding supported amino acid Schiff base ligands. Subsequent reaction with bis (acetylacetonato)dioxomolybdenum(VI) lead 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.

Graphical abstractIncorporation of ammo acid Schiff base ligands via reaction of acacAmpMCM-41 with different amino acids and subsequent treatment with MoO2(acac)2 affords a new class of heterogeneous molybdenum catalysts for oxidation of olefins with high activity and selectivity toward the formation of the corresponding epoxides.Figure optionsDownload full-size imageDownload high-quality image (100 K)Download as PowerPoint slide