Polyfunctional Action of Transition Metal Substituted Heteropolytungstates in Alkene Epoxidation by Molecular Oxygen in the Presence of Aldehyde Full article
Journal |
Journal of Molecular Catalysis A: Chemical
ISSN: 1381-1169 |
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Output data | Year: 1996, Volume: 114, Number: 1-3, Pages: 123-130 Pages count : 8 DOI: 10.1016/S1381-1169(96)00310-X | ||
Tags | Alkene epoxidation, Chain radical mechanism, Isobutyraldehyde, Molecular oxygen, Transition-metal-substitued heteropolytungstates | ||
Authors |
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Affiliations |
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Funding (1)
1 | Russian Foundation for Basic Research | 96-03-34215 |
Abstract:
Alkene epoxidation by dioxygen in the presence of isobutyraldehyde (IBA) and tetrabutylammonium salts of transition-metal-substituted heteropolyanions (HPAs), PW11MOn−39 (PW11M; M = CoII, MnII, CuII, PdII, TiIV, RuIV, and VV), has been studied in acetonitrile using trans-stilbene as a model substrate. The selectivity of epoxidation attains 95% at complete alkene conversion. The epoxide formation shows an induction period and is inhibited by 2,6-di-tert-butyl-4-methylphenol, indicating chain radical mechanism of the reaction. The formation of perisobutyric acid (PIBAc) was detected during oxidation process after the completion of the induction period. Decomposition of PIBAc as well as its interaction with trans-stilbene in the presence of PW11M has been stuided. PW11M with
M = CoII, PdII, and RuIV greatly enhance PIBAc homolytic decomposition and thus increase the rate of the degenerate branching in the chain radical process of alkene-aldehyde
co-oxidation. HPAs with the other metals are much less active in PIBAc decomposition and most likely catalyze the co-oxidation process by generating chain-initiating acyl radicals from IBA followed by the addition of O2 with the formation of acylperoxy radicals responsible for epoxidation. The influence of PW11M on the different elementary steps of the chain radical process depends on the M nature and HPA concentration. In most cases HPAs behave as catalysts at their low concentrations and as inhibitors at high concentrations.
Cite:
Kholdeeva O.A.
, Grigoriev V.A.
, Maksimov G.M.
, Fedotov M.A.
, Golovin A.V.
, Zamaraev K.I.
Polyfunctional Action of Transition Metal Substituted Heteropolytungstates in Alkene Epoxidation by Molecular Oxygen in the Presence of Aldehyde
Journal of Molecular Catalysis A: Chemical. 1996. V.114. N1-3. P.123-130. DOI: 10.1016/S1381-1169(96)00310-X WOS Scopus РИНЦ
Polyfunctional Action of Transition Metal Substituted Heteropolytungstates in Alkene Epoxidation by Molecular Oxygen in the Presence of Aldehyde
Journal of Molecular Catalysis A: Chemical. 1996. V.114. N1-3. P.123-130. DOI: 10.1016/S1381-1169(96)00310-X WOS Scopus РИНЦ
Dates:
Published print: | Dec 23, 1996 |
Published online: | Dec 16, 1999 |
Identifiers:
Web of science | WOS:A1996WC26500012 |
Scopus | 2-s2.0-0030599607 |
Elibrary | 13234146 |
Chemical Abstracts | 1996:737387 |
Chemical Abstracts (print) | 126:103957 |
OpenAlex | W2004291555 |