Ionic complex of Vanadyl(IV) in the polymerization of 2-hydroxyethyl methacrylate as probed by EPR

The vanadyl ionic complex VO(DMSO)₅(ClO₄)₂ (I) exhibits high catalytic activity in the polymerization of 2-hydroxyethyl methacrylate (HEMA). The changes in the vanadium oxidation state during polymerization under argon and in the presence of oxygen were studied by EPR. Under aerobic conditions, the HEMA chain propagation radical was detected; this indicates the presence of a radical chain polymerization pathway caused by the ability of I to perform one-electron reduction of molecular O₂. The radical generation rate is controlled by the initial concentration of I: its increase results in the formation of inactive species, presumably, μ-peroxo complexes V^v-O-O-V^v. It was shown by kinetic methods that the radical-chain pathway initiated by the reaction of I with O₂ is not crucial in the HEMA polymerization.     

Oxidative transformations of cyclohexene hydroperoxide catalyzed by penta (dimethylsulfoxido) vanadyl hexathiocyanatoplatinate

Conclusions Oxidation of cyclohexenyl hydroperoxide by molecular oxygen in the presence of penta(dimethylsulfoxido)vanadyl hexathiocyanatoplatinate proceeds at a high rate at low temperatures with the formation of bifunctional, oxygen-containing products. The main route of the reaction is the molecular oxidation of the hydroperoxide with ring opening in a complex [Cat_m...HOOR_n]; oxidation of cyclohexenyl hydroperoxide to a dihydroperoxide takes place simultaneously by a chain mechanism.Deceased.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 48–53, January, 1987.     

Immobilized Osmium Clusters in the Processes of Liquid-Phase Oxidation of Cycloxehene

The reaction of catalytic hydroxylation of olefins by organic hydroperoxides in the presence of osmium carbonyl clusters supported on polymer matrices is studied. The process occurs with the predominant formation of unsaturated alcohols. The oxidative coupling of olefins with the formation of nonconjugated dienes and in which the double bonds remain intact occurs in parallel. In the course of the reaction, changes in the chemical structures of the initial osmium clusters are not observed.     

Study of the morphology of network material obtained by the catalytic polymerization of 2-hydroxyethyl methacrylate

The vanadyl ion complex VO(DMSO)₅(ClO₄)₂ (I) exhibits high catalytic activity in the polymerization of 2-hydroxyethyl methacrylate (HEMA) in both aerobic and anaerobic conditions. A feature of I is the formation of a network structure capable of swelling in aqueous medium. On the grounds of studying the elastic properties of hydrogels, the concentrations of elastically active chains n _c in a network of bulk poly(HEMA) is determined. An increase in the cross-link density is observed with increasing concentration of I. The topological structure and morphology of poly(HEMA) are investigated; structural manifestations of the bifunctional nature of the catalyst and two directions of polymerization initiation are found.