Kinetics of Hydroperoxide Epoxidation of 1-Octene in the Presence of MoB2

We have studied the kinetics of the process of epoxidation of 1-octene by tert-butyl hydroperoxide in the presence of molybdenum boride MoB₂. We have studied the effect of the concentrations of starting materials and reaction products on the process. We suggest a kinetic scheme and we calculate the kinetic parameters of the process.     

The study of cyclooctene oxidation with molecular oxygen catalyzed by VSi2

The catalytic effect of VSi₂ on initial stages of the liquid-phase oxidation of cyclooctene by molecular oxygen was studied. The vanadium disilicide influences on the oxidation process in the presence of hydroperoxide. VSi₂ takes part in a radical formation stage by catalysis of hydroperoxide decomposition reaction. The catalyst was investigated before and after reaction using FTIR spectroscopy. From the data obtained, the kinetic model of the catalytic oxidation process was proposed and the equation for the reaction rate was derived. The equation has described all observed dependences of reaction rate on the concentration of reactants and content of catalyst.      

Structural investigation of the antibiotic sporaviridin: 11—Molecular secondary ion mass spectral studies on the constituent pentasaccharides viridopentaoses

Molecular secondary ion mass spectra of three pentasaccharides, viridopentaoses A, B and C, using various matrices, are discussed. The appearance of the molecular ion species is dependent upon the relative proton affinities between the sample and the organic matrix material. However, the presence of sodium ion, rather than proton, also greatly influences the appearance of the molecular ion species. The glycosidic linkages are mainly cleaved between the glycosidic oxygen atom and the anomeric carbon atom to give informative sugar sequence ions. These fragmentations have been confirmed by the linked scanning technique (B/E).     

Kinetic study of hydroperoxide epoxidation of 1‐octene in the presence of molybdenum disilicide as a catalyst in a low concentration range of olefin

The kinetic regularities of the influence of low 1‐octene concentrations on its epoxidation by tert‐butyl hydroperoxide in the presence of molybdenum disilicide (MoSi₂) as a catalyst were investigated. The minimum in the dependence of the initial rate of hydroperoxide consumption on 1‐octene concentration was observed. The kinetic scheme of epoxidation, which includes the competition between hydroperoxide and olefin for the catalytic active centers, was proposed. The equation for the reaction rate was derived according to the kinetic scheme. The kinetic parameters of epoxidation were calculated. © 2009 Wiley Periodicals, Inc. Int J Chem Kinet 41: 623–628, 2009     

FTIR investigation into transition metal disilicides as catalysts for <Emphasis Type="Italic">tert</Emphasis>-butyl hydroperoxide decomposition

Disilicides of molybdenum, tungsten, tantalum, and titanium were studied using FTIR spectroscopy to establish the origin of their different catalytic activities in the decomposition of tert-butyl hydroperoxide. The FTIR spectra of the metal disilicides before and after the decomposition reaction show that their different catalytic activities are caused not only by the nature of the transition metal, but also by different abilities of their surfaces to adsorb water. The increase in the catalyst’s ability to adsorb water leads to a decrease in catalyst activity.     

Synthesis, physical–chemical, and catalytic properties of mixed compositions Ag/H3PMo12O40/SiO2

Deposited catalysts composition H₃PMo₁₂O₄₀/SiO₂ and Ag/H₃PMo₁₂O₄₀/SiO₂ have been synthesized on the basis of fumed silica, including milling technique. Physical–chemical characteristics of prepared catalysts have been studied by means of XRD, DTA-TG, FTIR, UV–Vis spectroscopy, and adsorption of nitrogen. Catalysts possess meso- or meso-macroporous structure and contain deposited Keggin heteropolycompounds. Deposition of heteropolycompounds on support with high specific surface area results in increase of selectivity to epoxide in epoxidation reactions. The use of milling during catalyst synthesis leads to further growth of selectivity of epoxides formation.