Highly Selective Thioether Oxidation with H2O2 Catalyzed by Zr‐Substituted Keggin Phosphotungstate. Mechanistic Insights Full article
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ChemCatChem
ISSN: 1867-3880 , E-ISSN: 1867-3899 |
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| Output data | Year: 2024, Volume: 16, Number: 7, Article number : e202301374, Pages count : 10 DOI: 10.1002/cctc.202301374 | ||||
| Tags | homogeneous catalysis • hydrogen peroxide • Keggin phosphotungstate • sulfoxidation •zirconium | ||||
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Funding (1)
| 1 | Russian Science Foundation | 22-23-00410 |
Abstract:
The Zr-monosubstituted phosphotungstate (Bu4N)8[{PW11O39Zr(μ-OH)(H2O)}2] (1) is a highly active and selective catalyst for thioether sulfoxidation with aqueous H2O2 in acetonitrile or acetonitrile/ethanol. The reaction proceeds unprecedentedly fast and completes within seconds at room temperature. Various sulfides produce corresponding sulfoxides with selectivity of 98–99% and oxidant utilization efficiency of 92–99%. The reaction mechanism was investigated using test substrates, kinetic, isotopic labeling, and spectroscopic tools. The oxidation of thianthrene-5-oxide and competitive sulfide−sulfoxide oxidation point to an electrophilic oxidation mechanism, but a V-shaped Hammett plot found for oxidation of p-substituted thioanisoles may suggest a biphilic nature of active species. Kinetic study revealed that the rate-limiting step of the reaction is the interaction of a peroxo zirconium intermediate with organic substrate. ATR-FT-IR and 31P NMR spectroscopic studies coupled with stoichiometric experiments indicated that peroxo species capable of transferring oxygen atom to thioethers are dimeric side-on mono- and diperoxo complexes, [Zr2(μ-η2:η2-O2){PW11O39}2(H2O)x]8- (I) and [{Zr(μ-η2-O2)}2(PW11O39)2(H2O)y]10-(II), and monomeric Zr-hydroperoxo [Zr(η2-OOH)PW11O39]4‒ (III) and peroxo [Zr(η2-O2)PW11O39]5‒ (IV) species, which dominate at high excess of H2O2. While I and III are endowed with electrophilic oxygen, which can be transferred to electron-rich sulfides, more negatively charged II and IV preferably react with thioethers comprising electron-withdrawing substituents.
Cite:
Zalomaeva O.V.
, Maksimchuk N.V.
, Marikovskaya S.M.
, Antonov A.A.
, Kholdeeva O.A.
Highly Selective Thioether Oxidation with H2O2 Catalyzed by Zr‐Substituted Keggin Phosphotungstate. Mechanistic Insights
ChemCatChem. 2024. V.16. N7. e202301374 :1-10. DOI: 10.1002/cctc.202301374 WOS Scopus РИНЦ AN OpenAlex
Highly Selective Thioether Oxidation with H2O2 Catalyzed by Zr‐Substituted Keggin Phosphotungstate. Mechanistic Insights
ChemCatChem. 2024. V.16. N7. e202301374 :1-10. DOI: 10.1002/cctc.202301374 WOS Scopus РИНЦ AN OpenAlex
Dates:
| Submitted: | Oct 28, 2023 |
| Accepted: | Dec 5, 2023 |
| Published online: | Dec 19, 2023 |
| Published print: | Apr 9, 2024 |
Identifiers:
| Web of science: | WOS:001130080500001 |
| Scopus: | 2-s2.0-85180180396 |
| Elibrary: | 63358579 |
| Chemical Abstracts: | 2023:2663367 |
| OpenAlex: | W4389347848 |