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Title
Japanese:Investigation of the Reaction Mechanism for the Epoxidation of Alkenes with Hydrogen Peroxide Catalyzed by a Protonated Tetranuclear Peroxotungstate with NMR Spectroscopy, Kinetics, and DFT Calculations. 
English:Investigation of the Reaction Mechanism for the Epoxidation of Alkenes with Hydrogen Peroxide Catalyzed by a Protonated Tetranuclear Peroxotungstate with NMR Spectroscopy, Kinetics, and DFT Calculations. 
Author
Japanese: Ryo Ishimoto, Keigo Kamata, Noritaka. Mizuno.  
English: Ryo Ishimoto, Keigo Kamata, Noritaka. Mizuno.  
Language English 
Journal/Book name
Japanese:European Journal of Inorganic Chemistry 
English:European Journal of Inorganic Chemistry 
Volume, Number, Page Vol. 2013    No. 10-11    pp. 1943-1950
Published date 2013 
Publisher
Japanese:Wiley-VCH Verlag GmbH & Co. KGaA 
English:Wiley-VCH Verlag GmbH & Co. KGaA 
Conference name
Japanese: 
English: 
Conference site
Japanese: 
English: 
DOI https://doi.org/10.1002/ejic.201201058
Abstract For the epoxidn. of cyclooctene with hydrogen peroxide (H2O2), the catalytic activity of a dinuclear peroxotungstate, [{WO(O2)2}2(ﾎｼ-O)]2-, is strongly dependent on additives, and HClO4 is the most effective. The reaction of [{WO(O2)2}2(ﾎｼ-O)]2- with HClO4 (0.5 equiv.) gives a protonated tetranuclear peroxotungstate, TPA3 [H{W2O2(O2)4(ﾎｼ-O)}2]3- (I). The diastereoselectivity for epoxidn. of 3-methyl-1-cyclohexene shows that steric constraints of the active site of I are comparable to those of di- and tetranuclear peroxotungstates with XO4n- ligands (X = SeVI, AsV, PV, SVI, and SiIV). The lowest XSO [XSO = (nucleophilic oxidn.)/(total oxidn.)] value of 0.13 for the I-catalyzed oxidn. of thianthrene 5-oxide among peroxotungstates reveals that I has the most electrophilic active oxygen species. Kinetic and spectroscopic results show that an inactive species (I') is reversibly formed by the reaction of I with water. Reaction rates for the catalytic epoxidn. show first-order dependences on concns. of alkene and I and a zero-order dependence on concns. of H2O2. All these results indicate that oxygen transfer from I to a C=C double bond in an alkene is the rate-detg. step. Computational studies support the proposed reaction mechanism. [on SciFinder(R)]

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