Kinetics and mechanism of (salen)MnIII–catalysed hydrogen peroxide oxidation of alkyl aryl sulphides |
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| Authors: | Arunachalam Chellamani Nainamohamed Ismail Alhaji Seenivasan Rajagopal |
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| Institution: | 1. Department of Chemistry, Manonmaniam Sundaranar University, Tirunelveli – 627 012, IndiaDepartment of Chemistry, Manonmaniam Sundaranar University, Tirunelveli – 627 012, India.===;2. Department of Chemistry, Manonmaniam Sundaranar University, Tirunelveli – 627 012, India;3. School of Chemistry, Madurai Kamaraj University, Madurai – 625 021, India |
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| Abstract: | The kinetics of (salen)MnIII complexes catalysed oxidation of aryl methyl and alkyl phenyl sulphides with hydrogen peroxide have been investigated at 25°C in 80% acetonitrile – 20% water spectrophotometrically. The reaction follows first‐order kinetics in (salen)MnIII complex and zero‐order kinetics in hydrogen peroxide. The order of the reaction with respect to sulphide is fractional and saturation in reaction rate occurs at higher sulphide concentrations. The pseudo first‐order rate constants have been analysed as per Michaelis–Menten kinetics to obtain the values of k2, the oxidant‐substrate complex decomposition rate constant, and K, the oxidant‐substrate complex formation constant. The effects of nitrogenous bases, free radical inhibitor and changes in solvent composition have also been studied. A suitable mechanism, supported by electronic‐oxidant and electronic‐substrate effect studies, involving a manganese(III)‐hydroperoxide complex as reactive species has been proposed. Copyright © 2007 John Wiley & Sons, Ltd. |
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| Keywords: | (salen)MnIII complexes hydrogen peroxide organic sulphides catalysed oxidation mechanism |
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