Olefin oxidation, methyltrioxorhenium

F. E. Kuhn, A. Scherbaum, and W. A. Flerrmann, Methyltrioxorhenium and Its Applications in Olefin Oxidation, Metathesis and Aldehyde Olefination, J. Organomet. Chem. 689, 4149-4164 (2004). 

UV-Vis spectrophotometry has also been helpful to study the kinetics of olefin oxidation with hydrogenperoxide using methyltrioxorhenium (MTO) in the ionic liquids [C2mim][BF4], [C4mim][BF4], [C4mim][N03] and [C4py][BF4] [23],... 

W. A. Hemnaim, R. W. Fischer, D. W. Marz, Multiple bonding between main group elements and transition metals. 100. Part 2. Methyltrioxorhenium as catalyst for olefin oxidation, Angew. Chem. Int. Ed. Engl. 30, 1638-1641 (1991). 

Hermann WA, Fischer RW, Marz DW. Methyltrioxorhenium as catalyst for olefin oxidation. Angew Chem Int Ed 1991 30 1638-1641. 

The oxidation of alkenes and allylic alcohols with the urea-EL202 adduct (UELP) as oxidant and methyltrioxorhenium (MTO) dissolved in [EMIM][BF4] as catalyst was described by Abu-Omar et al. [61]. Both MTO and UHP dissolved completely in the ionic liquid. Conversions were found to depend on the reactivity of the olefin and the solubility of the olefinic substrate in the reactive layer. In general, the reaction rates of the epoxidation reaction were found to be comparable to those obtained in classical solvents. 

The TB ( + )-l adduct of methyltrioxorhenium [(+ )-Re03CH3], characterized by its crystal structural and spectroscopic data, was reported by Herrmann et al. The catalytic properties of this complex were tested in the epoxidation of olefins and the oxidation of sulfides. However, no enantioselective reactions of the pro-chiral olefins and sulfides were observed (97JOM(538)203). 

Re has recently come to the forefront in liquid phase oxidation catalysis, mainly as a result of the discovery of the catalytic properties of the alkyl compound CH3Re03 [methyltrioxorhenium (MTO)]. MTO forms mono-and diperoxo adducts with H2O2 these species are capable of transferring an oxygen atom to almost any nucleophile, including olefins, allylic alcohols, sulfur compounds, amides, and halide ions (9). Moreover, MTO catalysis can be accelerated by coordination of N ligands such as pyridine (379-381). An additional effect of such bases is that they buffer the strong Lewis acidity of MTO in aqueous solutions and therefore protect epoxides, for example. 

The simple organorhenium(VII) compound methyltrioxorhenium (Structure 1 in Scheme 1) - called MTO - has developed a plethora of applications in catalytic processes [1], This rapid development occurred in the decade of 1990-2000. The epoxidation of olefins (cf. Section 2.4.3) became attractive to industrial applications. There is sound evidence that MTO represents the most efficient catalyst for this process, being active even for highly dilute solutions of hydrogen peroxide. The latter oxidant is not decomposed by MTO, as opposed to many other metal complexes (cf. Section 3.3.13.1). 

W. Adam, C. R. Saha-Moller, O. Weichold, NaY zeolite as host for the selective heterogeneous oxidation of silanes and olefins with hydrogen peroxide catalyzed by methyltrioxorhenium, J. Org. Chem. 65 (2000) 2897. 

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