Hydrogen peroxide molecular model

Like hydrogen peroxide the inorganic substances hydrazine (H2NNH2) and hydroxylamine (H2NOH) possess conformational mobility Wnte stmctural representations or build molecular models of two different staggered conformations of (a) hydrazine and (b) hydroxylamine... 

Using this approach of a selectivity term SPFR Sunder and Hempel (1996) successfully modeled the oxidation of small concentrations of Tri- and Perchloroethylene (c(M)a = 300-1300 pg D) by ozone and hydrogen peroxide in a synthetic ground water (pH = 7.5-8.5 c(Sj) = 1-3 mmol C03 L"1). In this study an innovative reaction system was used the oxidation was performed in a tube reactor and mass transfer of gaseous ozone to pure water was realized in a separate contactor being located in front of the tube reactor. By this way a homogeneous system was achieved. Since the two model compounds react very slowly with molecular ozone (kD < 0.1 L mol-1 s "1), nearly the complete oxidation was due to the action of hydroxyl radicals, which were produced from the two oxidants (03/H202). With... 

Much attention has focused on vitamin K 1 because of its function as an obligatory cofactor in enzymic sequences central to blood clotting. The role of molecular oxygen in the formation of vitamin K oxide 2 has been studied intensively, and the mechanism of the 1 —> 2 transformation has been the subject of much controversy. Oxidation of 1 with basic hydrogen peroxide also gives 2, and two obvious mechanisms can be postulated for this model oxidation. 180 labelling studies have been used to distinguish between these mechanisms. 

The reactions of the several manganese gluconate complexes with molecular oxygen and hydrogen peroxide have been studied in terms of stoichiometry and reaction kinetics. Reaction mechanisms are proposed on the basis of the kinetic data. In addition, the thermodynamic and mechanistic characteristics of an ideal model system for photosystem-II are analyzed and evaluated. 

Alves, V, Capanema, E., Chen, C. L., and Gratzl, J., Comparative studies on oxidation of lignin model compounds with hydrogen peroxide using Mn(IV)-Me(3)TACN and Mn(IV)-Me4DTNE as catalyst. J Molecular Catalysis A-Chemical 2003, 206 (1-2), 37-51. 

Fe20(0Ac)2Cl2(bipy)2 successfully hydroxylates C6, C3, and C2 alkanes when tert-butyl hydrogen peroxide (TBHP) is used as the oxygen donor ([5] [TBHP]-.[substrate] = 1 150 1100) the observed reactivity is C6 > C3 > C2 (Table IV). This work represents the first report of the oxidation of a small molecular weight alkane (ethane) by a characterized iron model compound. Reactions of this complex with Zn dust and acetic acid under 1 atm of dioxygen with cyclohexane gave rise to only cyclohexanone (turnover number 2.5). The parent tetrameric compound, 6, was reported to be a more efficient catalyst. 

In addition to understanding the interaction of radiation with water, the nuclear industry must obviously also take into account the excess production of molecular hydrogen and hydrogen peroxide, and control this excess in order to avoid explosive conditions and corrosion of the water circuitries. Due to the working conditions of the current reactors (T > 310 °C, P > 100 atm in Pressurized Water Reactor, PWR), it is mandatory to predict the evolution ofthe chemistry when submitted to high temperature and pressure. Nevertheless, a few experiments have shown that the linear Arrhenius law model is not applicable at temperatures above 250 °C. Hydrogen production overestimates have been necessary in... 

Several possible mechanisms are available for UV-induced photoreactions of iron complexes. First, direct photoreactions involving ligand-to-metal charge transfer are likely to be one of the most important mechanisms for photoreaction [117,198,224]. Second, iron complexes can be reduced by photochemically-produced superoxide [207-209]. Superoxide ions are formed via the photoreduction of molecular oxygen by CDOM and it is one of the most concentrated radicals in seawater and is the precursor to hydrogen peroxide [Chapter 8]. Superoxide-induced reduction of Fe(iii) is an important mechanism in certain lakes [207]. However, the fact that Fe(ii) photoproduction can be more rapid in oxygen-free water than in air-saturated water in acidic estuaries [59] or model systems with well-defined organic acid complexes of Fe(iii) [117] indicates that direct photolysis of Fe(iii) is likely to be a dominant mechanism for Fe(ii) photoproduction in many aquatic systems. 

Superoxide dismutases are a class of oxido-reductase enzymes which contain either Cu, Fe, or Mn at the active site and catalyze the dismutation of superoxide (1), the one-electron reduction product of molecular oxygen (Eqs. 1 and 2, where M" is the metalloenzyme in the reduced state and M" is the enzyme in the oxidized state) to oxygen and hydrogen peroxide. The SOD enzymes have been shown to have efficacy in animal models of disease states proposed to be, in part, mediated by superoxide, such as myocardial ischemia-reperfusion injury, " inflammation, and cerebral ischemia-reperfusion injury. Evidence for superoxide as a mediator... 

In this contribution we report on the incorporation of tin into the mesoporous molecular sieves MCM-41 and MCM-48 comparing traditional hydrothermal approach with microwave synthesis of these materials. X-ray powder diffraction, nitrogen adsorption isotherms, scanning electron microscopy and FUR of probe molecules were employed to characterize these molecular sieves. Oxidation of adamantanone with hydrogen peroxide was used as model reaction. 

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