Selective oxidation of thioanisole with hydrogen peroxide using copper complexes encapsulated in zeolite: Formation of a thermally stable and reactive copper hydroperoxo species

[Cu(terpy)]²⁺ complexes encapsulated into Na-Y zeolite ([Cu(terpy)]²⁺@Y) were prepared, and their catalytic activities for the oxidation of sulfides using hydrogen peroxide were investigated. Several spectroscopic results, as well as elemental analysis, demonstrated the formation of [Cu(terpy)]²⁺ complexes in supercages of Y-zeolite. [Cu(terpy)]²⁺@Y exhibited high selectivity for the oxidation of thioanisole into methylphenylsulfoxide when H₂O₂ was used. The kinetic study of this oxidation at the catalyst [Cu(terpy)]²⁺@Y suggests that the reaction of [Cu(terpy)]²⁺ species with H₂O₂ is the rate-determining step. The oxidation of thioanisole, benzene, and 2-phenylethylamine using [[Cu(terpy)]²⁺@Y]∗, which was prepared from the reaction between [Cu(terpy)]²⁺@Y and H₂O₂, quantitatively proceeded to methylphenylsulfoxide, phenol, and 2-amino-1-phenylethanol, respectively. The reaction of [Cu(terpy)]²⁺@Y and H₂O₂ was found to yield thermally stable but active Cu^II-OOH species in [Cu(terpy)]²⁺@Y.