Selective and Reusable Oxidation of Sulfides to Sulfoxides with Hydrogen Peroxide Catalyzed by Organic–Inorganic Polyoxometalate-Based Frameworks

Abstract

Several organic-inorganic polyoxometalatebased frameworks such as HSiW-MOF, PMo-MOF, HPMo-MOF and PW-MOF were prepared and characterized by Elemental analysis, UV-Vis, FT-IR and XRD. Thioanisole was used as the model of sulfur compound in the oxidation reaction. The effects of reaction time, type of solvent, amount of catalyst and oxidants in this catalytic system were investigated. At optimum conditions, PMo-MOF and PW-MOF are more active catalysts with respect to H 2 O 2 . Oxidation of various sulfides to sulfoxides using 30 % aqueous hydrogen peroxide as oxidant under mild reaction conditions in 90-100 % conversion and 95-100 % selectivity to sulfoxideswas performed. Both catalysts showed high catalytic activity in the oxidation of different sulfides with actively functional groups such as the hydroxyl group and C=C bonds. The heterogeneous catalyst (PW-MOF) could be recovered easily and reused five times without significant loss of its catalytic activity. Graphical AbstractS R R CH 3 OH, Room Temp. POM-MOF, H 2 O 2 S R R O

Ratio-Controlled Precursors of Anderson–Evans Polyoxometalates: Synthesis, Structural Transformation, and Magnetic and Catalytic Properties of a Series of Triol Ligand-Decorated {M2Mo6} Clusters (M = Cu2+, Co2+, Ni2+, Zn2+)

“…Gentle oxidation in many cases is very important because the intermediate oxidation state of thioethers such as sulfoxides is usually required for the preparation of drug molecules . The POM catalysts with strong oxidation activity for the full oxidation of thio compounds and other substrates can be found in many publications. , However, the higher selectivity of incomplete oxidation is less reported, and the known strategy is to incorporate POMs into the bone of metal–organic framework compounds for synergistic catalysis with the framework environment, while the corresponding POM alone cannot afford such a higher catalytic conversion and selectivity for sulfoxide products . Using electrostatic interaction, organic cations substitute for the counterions of POMs to form supramolecular complexes, which also afford increased activity for the oxidation of thioanisole to chiral sulfoxide when chiral ligands are employed. , More examples concerning the incomplete oxidation products of thioethers are listed in Table S2 for an intuitive contrast, where the catalysts are clusters or metallic oxides.…”

Two novel supramolecular structures of Evans–Showell type polyoxometalate for heterogeneous and efficient catalytic conversion of different sulfides

“…[21][22][23][24][25][26] To realize the heterogenization of POM anions, many POM-based metal-organic complexes with covalently-bonded frameworks on different dimensions have shown excellent performance in practical conversion reactions of different sulfides. [27][28][29][30] For example, Liu et al synthesized a novel polyoxovanadate-based metalorganic framework (POV-MOF) to achieve efficient conversion of different sulfides under mild conditions due to the excellent catalyst-oxidant electronic band structure matching. 31 Niu used a crown-shaped ligand to modify Anderson type polyoxometalate {TeMo 6 } and obtained its hexamer to achieve sulfide oxidation with the assistance of organic hydrogen peroxide.…”

H3PMo12O40@MOF as a New Catalytic System for Cycloxexanone Oxidation to Adipic Acid

“…To further make POMs more stable and efficient, options and strategies have been attempted. Among them, the introduction of highly porous crystalline solids as MCM-41 (Jatupisarnpong, 2012) or SBA-15 (Meng, 2015) to support the POMs or Metal-organic frameworks (MOFs) to incorpore them (Haddadi, 2015). MOFs are a family of organic-inorganic hybrid materials containing nanometric pores and channels built from organic ligands bridging metal ions (Lik, 2014).…”