摘要：

The kinetics of oxidation of three alpha beta-unsaturated compounds, CH2CHX (X=CN, CONH2 and CO2-) by bis(dihydrogentellurato)metallate(III) ions ([MIII-(H2TeO6)2]5-, M=Cu or Ag) have been studied in an alkaline medium. The reactions take place according to the rate expression: The k3 values are 2.42*10-2, 1.67*10-2 and 1.10*10-2mol6dm-2s-1 for oxidations of the respective substrate by the copper(III) complex and 1.49*10-2, 1.07*10-2 and 0.80*10-2mol6dm-2s-1, respectively, in the oxidations by silver(III), all at 303K. [CuIII(H2TeO6)2]5- reacts faster than the corresponding reactions with [AgIII(H2TeO6)2]5-. The oxidation rates follow the order: CN CONH2CO2-. The oxidations of the substrates by [CuIII(H2TeO6)2]5- take place by an outer-sphere mechanism, unlike [AgIII-(H2TeO6)2]5-, which reacts by an inner-sphere mechanism. The substrates are oxidized to diols under kinetic control and a tentative reaction mechanism leading to the formation of oxidation products is suggested. The activation parameters of the reactions have been evaluated.

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