- Selective oxidation of alcohols with hydrogen peroxide catalyzed by hexadentate binding 8-quinolinolato manganese(III) complexes
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A series of hexadentate 8-quinolinolato manganese(III) complexes were synthesized and proven to own a distorted octahedral geometry via elemental analysis, solid UV-vis spectroscopy and Hartree-Fock/3-21G+ calculation. These Mn(III) complexes were found to be more efficient than their corresponding tetradentate 8-quinolinolato manganese(II) and salen-MnIIIOAc for the oxidation of alcohols in acetone medium, being due to their special hexadentate binding structures that could open an axial Mn{single bond}O bond to form the more active pentadentate structures in the presence of aqueous hydrogen peroxide, as supported by UV-vis spectra. The halogen substituents in ligand's aryl ring could significantly enhance the catalytic activities and 5-chloro-7-iodo-8-quinolinolato manganese(III) gave the highest turnover number (TON). A reasonable mechanism for the present catalytic system was proposed.
- Ye, Zhengpei,Fu, Zaihui,Zhong, Sheng,Xie, Fang,Zhou, Xiaoping,Liu, Fenglan,Yin, Dulin
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experimental part
p. 110 - 115
(2009/04/13)
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- Polyfluorinated quaternary ammonium salts of polyoxometalate anions: Fluorous biphasic oxidation catalysis with and without fluorous solvents
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[Matrix presented] Polyfluorinated quaternary ammonium cations, [CF 3(CF2)7(CH2)3] 3CH3N+ (RFN+), were synthesized and used as countercations for the [WZnM2(H 2O)2(ZnW9O34)2] 12- (M = Mn(II), Zn(II)) polyoxometalate. The (RFN +)12[WZnM2(H20)2 (ZnW9O34)2] compounds were fluorous biphasic catalysts for alcohol and alkenol oxidation, and alkene epoxidation with aqueous hydrogen peroxide. Reaction protocols with or without a fluorous solvent were tested. The catalytic activity and selectivity was affected by both the hydrophobicity of the solvent and the substrate.
- Maayan, Galia,Fish, Richard H.,Neumann, Ronny
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p. 3547 - 3550
(2007/10/03)
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- Process for cooxidizing organic compounds, process for producing epoxy compounds and process for producing esters or lactones
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According to the inventive co-oxidation process of organic compounds, (A) a compound selected from (A1) a compound having a non-aromatic ethylenic bond and (A2) a ketone or an alcohol corresponding to the ketone is oxidized by molecular oxygen in the presence of N-hydroxyphthalimide or another imide compound and in the coexistence of (B) a compound oxidizable by the imide compound and oxygen and different from the compound (A). As the compound (B), (a) primary or secondary alcohols (e.g., benzhydrol, cyclohexanol), (b) compounds each having a carbon-hydrogen bond at the adjacent position to an unsaturated bond (e.g., tetralin, ethylbenzene) and the like can be used. According to this process, a corresponding epoxy compound from the compound (A1) having a non-aromatic ethylenic bond, and a corresponding ester or lactone from the ketone or its corresponding alcohol (A2) can be obtained in satisfactory yields.
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- Mechanism of asymmetric epoxidation. 1. Kinetics
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The rate of titanium-tartrate-catalyzed asymmetric epoxidation of allylic alcohols is shown to be first order in substrate and oxidant, and inverse second order in inhibitor alcohol, under pseudo-first-order conditions in catalyst. The rate is slowed by substitution of electron-withdrawing substituents on the olefin and varies slightly with solvent, CH2Cl2 being the solvent of choice. Asymmetric induction suffers when the size of the alkyl hydroperoxide is reduced. Kinetic resolution of secondary allylic alcohols is shown to be sensitive to the size of the tartrate ester group and insensitive to the steric nature of inhibitor alcohol. Most importantly, the species containing equimolar amounts of Ti and tartrate is shown to be the most active catalyst in the reaction mixture, mediating reaction at much faster rates than titanium tetraalkoxide alone.
- Woodard, Scott S.,Finn,Sharpless, K. Barry
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p. 106 - 113
(2007/10/02)
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