Heterogeneous H2O2-based selective oxidations over zirconium tungstate α-ZrW2O8

Catalytic properties of a crystalline zirconium tungstate, ZrW2O8, the material known mainly for its isotropic negative coefficient of thermal expansion, have been assessed for the liquid-phase selective oxidation of a range of organic substrates comprising C=C, OH, S and other functional groups usi...

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Published in:Dalton transactions : an international journal of inorganic chemistry 2024-01, Vol.53 (4), p.1528-1540
Main Authors: Vasilii Yu Evtushok, Ivanchikova, Irina D, Zalomaeva, Olga V, Gubanov, Alexander I, Kolesov, Boris A, Glazneva, Tatiana S, Kholdeeva, Oxana A
Format: Article
Language:English
Subjects:
Aldehydes
Epoxidation
Functional groups
Hydrogen peroxide
Infrared spectroscopy
Ketones
Leaching
Liquid phases
Oxidation
Oxidizing agents
Singlet oxygen
Substrates
Sulfones
Thermal expansion
Zirconium
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Summary:Catalytic properties of a crystalline zirconium tungstate, ZrW2O8, the material known mainly for its isotropic negative coefficient of thermal expansion, have been assessed for the liquid-phase selective oxidation of a range of organic substrates comprising C=C, OH, S and other functional groups using aqueous hydrogen peroxide as the green oxidant. Samples of ZrW2O8 were prepared by hydrothermal synthesis and characterised by N2 adsorption, PXRD, SEM, EDX, FTIR and Raman spectroscopic techniques. Studies by IR spectroscopy of adsorbed probe molecules (CO and CDCl3) revealed the presence of Brønsted acidic and basic sites on the surface of ZrW2O8. It was demonstrated that ZrW2O8 is able to activate H2O2 under mild conditions and accomplish the epoxidation of C=C bonds in alkenes and unsaturated ketones, oxidation of thioethers to sulfoxides and sulfones, along with the oxidation of alcoholic functions to produce ketones and aldehydes. The oxidation of tetramethylethylene and α-terpinene over ZrW2O8 revealed the formation of peroxidation products, 2,3-dimethyl-3-butene-2-hydroperoxide and endoperoxide ascaridole, respectively, indicating the involvement of singlet oxygen in the oxidation process. The ZrW2O8 catalyst preserves its structure and morphology under the turnover conditions and does not suffer from metal leaching. It can be easily recovered, regenerated by calcination, and reused without the loss of activity and selectivity.
ISSN:1477-9226
1477-9234
DOI:10.1039/d3dt03495j