Kinetics and Mechanism of Thioether Oxidation with H2O2 in the Presence of Ti(IV)-Substituted Heteropolytungstates Full article
Conference |
Physical Methods for Catalytic Research at the Molecular Level: International memorial K.I. Zamaraev conference 28 Jun - 2 Jul 1999 , Novosibirsk |
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Journal |
Journal of Molecular Catalysis A: Chemical
ISSN: 1381-1169 |
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Output data | Year: 2000, Volume: 158, Number: 1, Pages: 223-229 Pages count : 7 DOI: 10.1016/S1381-1169(00)00069-8 | ||
Tags | Hydrogen peroxide, Kinetics, Mechanism, Thioether oxidation, Titanium-substituted heteropolytungstates | ||
Authors |
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Affiliations |
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Funding (1)
1 | Russian Foundation for Basic Research | 96-03-34215 |
Abstract:
Kinetics of thioether oxidation with concentrated (86%) and diluted (35%) aqueous H2O2 in the presence of catalytic amounts of (Bu4N)7{[PW11O39Ti]2OH} dimeric heteropolytungstate (1) has been studied in acetonitrile. With 86% H2O2 the reaction was found to be first order in the oxidant, 0.5 order in the catalyst and practically independent on the sulfide concentration and its nature, whereas with 35% H2O2 the reaction was first order in both the catalyst and substrate, the order in the oxidant being changed from first to zero with increasing H2O2 concentration. Both 31P NMR and kinetic data are consistent with mechanism, including fast dissociation of 1 to the monomer (2), the equilibrium formation of active hydroperoxo complex PW11TiOOH (B) from 2, and interaction of B with thioether. The rate-limiting steps are the formation of B and the interaction of B with sulfide at low and high H2O concentrations, respectively. The kinetic study of stoichiometric reaction between B, generated in situ from inactive side-on peroxo complex PW11TiO2 (A), and thioethers showed first order dependence on both B and sulfide concentration, thus indicating that no binding of thioether to Ti(IV) occurs. The lack of Hammett-type correlation and specific products obtained in oxidation of benzyl phenyl sulfide allowed to rule out electrophilic oxygen transfer and suggest a mechanism that involves the formation of a thioether cation radical intermediate.
Cite:
Kholdeeva O.A.
, Kovaleva L.A.
, Maksimovskaya R.I.
, Maksimov G.M.
Kinetics and Mechanism of Thioether Oxidation with H2O2 in the Presence of Ti(IV)-Substituted Heteropolytungstates
Journal of Molecular Catalysis A: Chemical. 2000. V.158. N1. P.223-229. DOI: 10.1016/S1381-1169(00)00069-8 WOS Scopus РИНЦ
Kinetics and Mechanism of Thioether Oxidation with H2O2 in the Presence of Ti(IV)-Substituted Heteropolytungstates
Journal of Molecular Catalysis A: Chemical. 2000. V.158. N1. P.223-229. DOI: 10.1016/S1381-1169(00)00069-8 WOS Scopus РИНЦ
Dates:
Published online: | Jul 18, 2000 |
Published print: | Sep 8, 2000 |
Identifiers:
Web of science | WOS:000089201200025 |
Scopus | 2-s2.0-0034623041 |
Elibrary | 13360470 |
Chemical Abstracts | 2000:498686 |
Chemical Abstracts (print) | 133:334929 |
OpenAlex | W2074057192 |