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  • 1
    Electronic Resource
    Electronic Resource
    Quantum-chemistry and catalysis in oxidation of hydrocarbons (1981)
    s.l. : American Chemical Society
    Accounts of chemical research 14 (1981), S. 1-7 
    Details
    ISSN: 1520-4898
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ar00061a001
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  • 2
    Electronic Resource
    Electronic Resource
    On the molecular mechanism of catalytic oxidation of olefins (1991)
    Springer
    Catalysis letters 9 (1991), S. 297-309 
    Details
    ISSN: 1572-879X
    Keywords: Butane oxidation ; oxide catalysis ; molybdenum oxide catalysts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract In every oxidation reaction two reactants take part: oxygen and the molecule to be oxidized. The reaction may thus start either by activation of the dioxygen (electrophilic oxidation) or by activation of the hydrocarbon molecule (nucleophilic oxidation). The surface of an oxide catalyst for selective oxidation must thus be tailored to perform a complex multistep operation on the reacting molecules, at the same time hindering those interactions that could lead to unwanted byproducts. A theoretical description of chemical reactions may be attempted on the basis of the concept of the potential energy hypersurface for molecular motions. The minima on such a hypersurface correspond to stable systems; i.e., to reactants and products of the reaction network investigated. As the networks for the oxidation of hydrocarbons on oxide surfaces are relatively large systems, even the semiempirical computation is time-consuming and further simplifications of the model must be adopted to make full description feasible. Analysis of experimental data suggests that as the form of the transition state is already determined at the preliminary stage of the reaction, the energy gradient estimated from the difference of total energies at two points chosen at relatively large distances between the reactants may be taken as an indication of the potential barrier encountered on approach from a given direction. Thus, reaction pathways characterized by the lowest energy barriers may then be analyzed. Calculations were carried out for the reaction pathways in the system composed on non-activated and activated butene interacting with molecular or atomic oxygen. A general conclusion may be formulated that the important functions of active centers of the oxidation catalyst consist in the adsorption of the reacting molecules in the appropriate mutual orientation and in modification of their relative electrophilic-nucleophilic character.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00773187
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  • 3
    Electronic Resource
    Electronic Resource
    The pseudopotential-CI study of the interaction between ethylene and metal atoms, metal Oxides, and their cations (Me = Be, Mg, and Zn) (1986)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 29 (1986), S. 1535-1554 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Potential energy curves for the lowest singlet and triplet states of Me + C2H4, Me+ + C2H4, MeO, MeO + C2H4, and (MeO + C2H4)+ systems for Me = Be, Mg, and Zn have been determined employing PP-MRD-CI or an all electron MRD-CI procedure. A binding interaction in the ground state has been found for oxides, all cation systems, and the BeO + C2H4 system. In the cases of MgO + C2H4 and ZnO + C2H4, only low lying excited states exhibit attractive interactions. Among three oxides considered, BeO is less pronounced biradically than MgO and ZnO. In order to obtain a binding interaction between an oxide and the olefin in the ground state, the p orbital of the metal must be sufficiently involved in binding.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560290544
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  • 4
    Electronic Resource
    Electronic Resource
    Biosynthesis of Nitric Oxide - Quantum Chemical Modelling of Nω-Hydroxy-l-arginine Formation (1997)
    Weinheim : Wiley-Blackwell
    Chemistry - A European Journal 3 (1997), S. 609-613 
    Details
    ISSN: 0947-6539
    Keywords: amino acids ; biosynthesis ; hydroxylations ; nitric oxides ; semiempirical calculations ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The electronic structure (charge distribution, bond indices, character of the frontier orbitals) and geometry (bond distances and angles) of L-arginine and N-methyl-L-arginine were determined by means of the INDO procedure. The method was also adopted to model the conversion of L-arginine into N-hydroxy-L-arginine in biological systems. This revealed that the approach of diatomic O species does not result in reaction, whereas the approach of either an O atom or an O2- ion leads to insertion of oxygen and formation of hydroxy-L-arginine. The insertion of oxygen between the nitrogen and hydrogen atoms leads to more stable products than insertion into the C-H bond. The same results were obtained for N-methyl-L-arginine, and are consistent with the hypothesis that the inhibitive effect of N-substitution in L-arginine is of no importance for the first step in the biosynthesis of NO (hydroxylation process). The mechanistic considerations based on the charge distribution and frontier orbital characteristics led to the conclusion that the most probable mechanism of L-arginine hydroxylation consists in electrophilic attack of [FeO]3+ at the Nω-H bond, initiated by the reduction of L-arginine+, followed by insertion of oxygen and product oxidation.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chem.19970030417
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