Mono-copper substituted phosphotungstate was supported on hydrous zirconia by wet impregnation, characterized and evaluated for its catalytic activity in the solvent-free flexible oxidation of styrene using TBHP as oxidant.

In the present work, an attempt has been made to induce chirality in coppersubstituted phosphotungstate (PW 11 Cu) by functionalization with (S)-(+)-1-phenylethylamine (S-PEA) via a ligand substitution approach. The formation of a N→Cu dative bond was confirmed by 13 C NMR, while 1 H NMR, circular dichroism spectroscopy and optical rotation studies confirmed the introduction of chirality to the Keggin structure. The synthesized material was used as the heterogeneous catalyst for the asymmetric epoxidation of styrene using various green oxidants to obtain high enantiomeric excess (ee), and the reaction with molecular oxygen was found to give the best ee. Regeneration studies were carried out, and the catalyst was found to be suitable for the same. A probable mechanism is also proposed. A comparison with other copper-based polyoxometalate catalysts clearly demonstrate the superiority and novelty of the present catalyst in terms of the reaction conditions as well as the obtained ee.

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The present paper describes a facile microwave route for the synthesis of Cesium salt of mono‐copper substituted phosphotungstate, Cs5[PW11Cu(H2O)O39].4H2O, from H3PW12O40, CuCl2 and CsCl, its characterization and catalytic activity towards solvent‐free, selective epoxidation of cis‐cyclooctene using TBHP as the oxidant. In order to confirm the superiority of the microwave technique, the said complex was also synthesized by reflux method and the same studies were carried out. The present complex is found to be sustainable as well as recyclable without any change in % conversion as well as % selectivity towards epoxide. A detailed kinetic study showed an overall second order dependence of the reaction with respect to cyclooctene and TBHP.