Catalytic olefin epoxidation with a fluorinated organomolybdenum complex

• Published in: Journal of molecular catalysis. A, Chemical Vol. 363-364; pp. 237 - 244
• Main Authors: Hauser, Simone A., Cokoja, Mirza, Drees, Markus, Kühn, Fritz E.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.11.2012; Elsevier
• Subjects: Catalysis; catalysts; catalytic activity; Chemistry; Exact sciences and technology; Fluorinated solvents; General and physical chemistry; Homogeneous catalysis; Ionic liquids; molybdenum; nuclear magnetic resonance spectroscopy; olefin; Olefin epoxidation; Organomolybdenum complexes; oxidants; recycling; solvents; temperature; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; Organomolybdenum complexes; Ionic liquids; Fluorinated solvents; Olefin epoxidation; Homogeneous catalysis; Catalytic reaction; Transition element complexes; Stability; Organic hydroperoxide; Organometallic compound; Fluorine compound; NMR spectrometry; Oxidant; Carbonyl; Ionic liquid; Olefin; Epoxidation; Molybdenum complex; Recycling; Ethylenic compound; Catalyst; Room temperature
• ISSN: 1381-1169; 1873-314X
• DOI: 10.1016/j.molcata.2012.06.015

[Display omitted] ► [CpMo(CO)3CF3] acts as a pre-catalyst of the epoxidation of olefins. ► The performance of [CpMo(CO)3CF3] is compared to [CpMo(CO)3CH3]. ► Fluorinated solvents activate TBHP, improving of the catalyst performance. ► Several homogeneous reaction media, including an ionic liquid, were studied. ► The stability of the oxidised species allows catalyst recycling. Monomeric organomolybdenum carbonyl complexes of general formula [(η5-C5R5)Mo(CO)3X] (R=H, CH3, CH2Ph; X=alkyl, halide) are known to be pre-catalysts for olefin epoxidation. In this work, the application of a fluorinated complex, [CpMo(CO)3CF3] (Cp=η5-C5H5), is reported. With hexafluoroisopropanol as a solvent, a turnover frequency (TOF) of >6300h−1 was achieved in the epoxidation of cyclooctene with tert-butyl hydroperoxide (TBHP) as oxidant. So far, only ansa compounds of formula [Mo(η5-C5H4(CH(CH2)n)-η1-CH)(CO)3] are known to deliver better performances in catalytic epoxidation reactions at room temperature. [CpMo(CO)3CF3] was also applied in 2-phase catalytic epoxidation reactions. The high stability of the oxidised species allows catalyst recycling for multiple catalytic runs without significant loss of activity. Besides, the fluorinated complex enables – at this stage preliminary – mechanistic 19F NMR studies, indicating the nature of the catalytically active Mo-species, which has been an unresolved subject for some time.