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Süss-Fink, Georg

Nom
Süss-Fink, Georg
Affiliation principale
Fonction
Professeur ordinaire
Email
georg.suess-fink@unine.ch
Identifiants
https://libra.unine.ch/handle/123456789/385

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  • Publication
    Métadonnées seulement
    Oxidation of 2-propanol and cyclohexane by the reagent "Hydrogen peroxide - Vanadate anion - Pyrazine-2-carboxylic acid": Kinetics and Mechanism
    (2007)
    Kozlov, Yuriy N
    ;
    Romakh, Vladimir B
    ;
    Kitaygorodskiy, Alex
    ;
    Buglyo, Peter
    ;
    Süss-Fink, Georg 
    ;
    Shul'pin, Georgiy B
    The vanadate anion in the presence of pyrazine-2-carboxylic acid (PCA equivalent to pcaH) efficiently catalyzes the oxidation of 2-propanol by hydrogen peroxide to give acetone. UV-vis spectroscopic monitoring of the reaction as well as the kinetics lead to the conclusion that the crucial step of the process is the monomolecular decomposition of a diperoxovanadium(V) complex containing the pca ligand to afford the peroxyl radical, HOO center dot and a V(IV) derivative. The rate-limiting step in the overall process may not be this (rapid) decomposition itself but (prior to this step) the slow hydrogen transfer from a coordinated H2O2 molecule to the oxygen atom of a pca ligand at the vanadium center: "(pca)(O)V center dot center dot center dot O2H2" -> "(pca)(HO-)V-OOH". The V(IV) derivative reacts with a new hydrogen peroxide molecule to generate the hydroxyl radical ("V-IV" + H2O2 -> "V-V" + HO- + HO center dot), active in the activation of isopropanol: HO center dot + Me2CH(OH) -> H2O + Me2C center dot(OH). The reaction with an alkane, RH, in acetonitrile proceeds analogously, and in this case the hydroxyl radical abstracts a hydrogen atom from the alkane: HO center dot + RH -> H2O + R-center dot. These conclusions are in a good agreement with the results obtained by Bell and co-workers (Khaliullin, R. Z.; Bell, A. T.; Head-Gordon, M. J. Phys. Chem. B 2005, 109, 17984-17992) who recently carried out a density functional theory study of the mechanism of radical generation in the reagent under discussion in acetonitrile.
  • Publication
    Métadonnées seulement
    The kinetics and mechanism of cyclohexane oxygenation by hydrogen peroxide catalyzed by a binuclear iron complex
    (2003)
    Kozlov, Yuriy N
    ;
    Gonzalez-Cuervo, Laura
    ;
    Süss-Fink, Georg 
    ;
    Shul'pin, Georgiy B
    The binuclear iron complex containing 1,3,7-triazacyclononane and acetate bridges as ligands was found to catalyze effective oxidation of alkanes by hydrogen peroxide in acetonitrile at room temperature in the presence of pyrazine-2-carboxylic acid (P) as a cocatalyst. The primary reaction products were alkylhydroperoxides, which gradually decomposed to produce the corresponding ketones (aldehydes) and alcohols. Alkane activation was caused by the attack of hydroxyl radicals on a C-H alkane bond, which resulted in the formation of alkyl radicals. Hydroxyl radicals were generated in the rate-determining step of monomolecular decomposition of the iron diperoxo adduct with one P molecule. A kinetic model of the process that satisfactorily described the whole set of experimental data was suggested. The constants of supposed equilibria and the rate constant for the decomposition of the diperoxo complex of iron with P were estimated.