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[摘要]：The oxidation of 4-substituted phenyl phenyl sulfides was carried out with several oxo(salen) manganese(V) complexes in MeCN/H2O 9:1. The kinetic data show that the reaction is first-order each in the oxidant and sulfide. Electron-attracting substituents in the sulfides and electron-releasing substituents in salen of the oxo(salen) manganese(V) complexes reduce the rate of oxidation. A Hammett analysis of the rate constants for the oxidation of 4-substituted phenyl phenyl sulfides gives a negative rho value (rho = -2.16) indicating an electron-deficient transition state. The log k(2) values observed in the oxidation of each 4-substituted phenyl phenyl sulfide by substituted oxo(salen) manganese(V) complexes also correlate with Hammett sigma constants, giving a positive rho value. The substituent-, acid-, and solvent-effect studies indicate direct O-atom transfer from the oxidant to the substrate in the rate-determining step. |
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