A reusable catalytic system for sulfide oxidation and epoxidation of allylic alcohols in water catalyzed by poly(dimethyl diallyl) ammonium/polyoxometalate
Highly efficient oxidation of sulfides with hydrogen peroxide catalyzed by [SeO4{WO(O2)2}2]2−
作者:Keigo Kamata、Tomohisa Hirano、Noritaka Mizuno
DOI:10.1039/b907952a
日期:——
By using the selenium-containing dinuclear peroxotungstate at 0.005â0.1 mol%, various kinds of sulfides could be converted into the corresponding sulfoxides or sulfones in excellent yields with one or two equivalents of H2O2 with respect to the sulfide, respectively.
The selenium-containing dinuclear peroxotungstate, [(n-C4H9)4N]2[SeO4WO(O2)2}2] (I), acts as a homogeneous catalyst for the selective oxidation of various kinds of cyclic mono- and disulfides with 30% aqueous H2O2. The cyclic disulfides were selectively oxidized to the corresponding monosulfoxides with one equivalent of H2O2 with respect to the sulfides. In the presence of two equivalents of H2O2, the oxidation of dibenzothiophene gave the corresponding sulfone in 98% yield under the mild conditions. The negative Hammett Ï value (â0.62) for the competitive oxidation of p-substituted thioanisoles and the low XSO (XSO = (nucleophilic oxidation)/(total oxidation)) value of 0.14 for the I-catalyzed oxidation of thianthrene 5-oxide (SSO) revealed that I is a strong electrophilic oxidant. The reactivities of the di- and tetranuclear peroxotungstates with XO4nâ ligands (X = Se(VI), As(V), P(V), S(VI), and Si(IV)) were strongly dependent on the kinds of hetero atoms. The reaction rates for the sulfoxidation decreased with an increase in the XSO values and a peroxotungstate with a stronger electrophilicity was more active for the sulfoxidation. The kinetic and mechanistic investigations showed that the electrophilic attack of the peroxo oxygen at the sulfur atom is a key step in the sulfoxidation. The computational investigation supported the high chemoselectivitiy for the sulfoxidation of diallyl sulfide.
A reusable catalytic system for sulfide oxidation and epoxidation of allylic alcohols in water catalyzed by poly(dimethyl diallyl) ammonium/polyoxometalate
An effective catalyst based on a polyoxometalate and a polymer has been developed for the oxidation of sulfides and allylic alcohols under mild conditions in water.
基于多酸和聚合物的有效催化剂已经在水中温和条件下开发用于氧化硫化物和烯丙基醇。
[γ-1,2-H2SiV2W10O40] Immobilized on Surface-Modified SiO2 as a Heterogeneous Catalyst for Liquid-Phase Oxidation with H2O2
with TBA-I. The oxidation can be stopped immediately by removal of the solid catalyst, and vanadium and tungsten species can hardly be found in the filtrate after removal of the catalyst. These results rule out any contribution to the observed catalysis from vanadium and tungsten species that leach into the reaction solution, which means that the observed catalysis is truly heterogeneous in nature. In