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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
    Hydrogen peroxide oxygenation of alkanes including methane and ethane catalyzed by iron complexes in acetonitrile
    (2004)
    Shul'pin, Georgiy B
    ;
    Nizova, Galina V
    ;
    Kozlov, Yuriy N
    ;
    Gonzalez-Cuervo, Laura
    ;
    Süss-Fink, Georg 
    This paper describes an investigation of the alkane oxidation with hydrogen peroxide in acetonitrile catalyzed by iron(III) perchlorate (1), iron(III) chloride (2), iron(III) acetate (3) and a binuclear iron(III) complex with 1,4,7-triazacyclononane (4). The corresponding alkyl hydroperoxides are the main products. Nevertheless in the kinetic study of cyclohexane oxidation, the concentrations of oxygenates (cyclohexanone and cyclohexanol) were measured after reduction of the reaction solution with triphenylphosphine (which converts the cyclohexyl hydroperoxide to the cyclohexanol). Methane and ethane can be also oxidized with TONs up to 30 and 70, respectively. Chloride anions added to the oxidation solution with 1 activate the perchlorate iron derivative in acetonitrile, whereas the water as additive inactivates 2 in the H2O2 decomposition process. Pyrazine-2-carboxylic acid (PCA) added to the reaction mixture decreases the oxidation rate if 1 or 2 are used as catalysts, whereas compounds 3 and 4 are active as catalysts only in the presence of small amount of PCA. The investigation of kinetics and selectivities of the oxidations demonstrated that the mechanisms of the reactions are different. Thus, in the oxidations catalyzed by the 1, 3+PCA and 4+ PCA systems the main oxidizing species is hydroxyl radical, and the oxidation in the presence of 2 as a catalyst has been assumed to proceed (partially) with the formation of ferryl ion, (Fe-IV=O)(2+). In the oxidation catalyzed by the 4+PCA system (TONs attain 240) hydroxyl radicals were generated in the rate-determining step of monomolecular decomposition of the iron diperoxo adduct containing one PCA molecule. A kinetic model of the process which satisfactorily describes the whole set of experimental data was suggested. The constants of supposed equilibriums and the rate constant for the decomposition of the iron diperoxo adduct with PCA were estimated.
  • Publication
    Métadonnées seulement
    Hydroperoxidation of methane and other alkanes with H2O2 catalyzed by a dinuclear iron complex and an amino acid
    (2002)
    Nizova, Galina V
    ;
    Krebs, Bernt
    ;
    Süss-Fink, Georg 
    ;
    Schindler, Siegfried
    ;
    Westerheide, Lars
    ;
    Gonzalez-Cuervo, Laura
    ;
    Shul'pin, Georgiy B
    The compound [Fe-2(HPTB)([mu-OH)(NO3)(2)](NO3)(2).CH3OH.2H(2)O (1) containing a dinuclear iron(III) complex in which HPTB=N,N,N',N'-tetrakis(2-benzimidazolylmethyl)-2-hydroxo-1,3-diaminopro pane catalyzes the oxidation of alkanes with hydrogen peroxide in acetonitrile solution at room temperature only if certain amino acids (pyrazine-2-carboxylic, pyrazine-2,3-dicarboxylic or picolinic acid) are added to the reaction mixture. Alkyl hydroperoxides are formed as main reaction products. The turnover numbers attain 140 for cyclohexane, 21 for ethane and four for methane oxidation. The oxidation proceeds non-stereoselectively and bond selectivity parameters are low which testifies the participation of hydroxyl radicals in alkane functionalization. (C) 2002 Elsevier Science Ltd. All rights reserved.
  • Publication
    Métadonnées seulement
    Oxidations by the reagent 'O-2-H2O2 vanadate anion pyrazine-2-carboxylic acid'. Part 10 - Oxygenation of methane in acetonitrile and water
    (1998)
    Süss-Fink, Georg 
    ;
    Nizova, Galina V
    ;
    Stanislas, Sandrine
    ;
    Shul'pin, Georgiy B
    The oxidation of methane by a combination of air and hydrogen peroxide is effectively catalyzed in solution by a system composed of vanadate and pyrazine-2-carboxylic acid (PCA). In acetonitrile solution, containing the vanadate anion as tetrabutylammonium salt, the reaction gives, over a temperature range of 25 to 50 degrees C, methanol, carbon monoxide, formaldehyde, formic acid and carbon dioxide, the latter three compounds, however, being partially due to the oxidation of the acetonitrile used as the solvent, especially at higher temperatures. In aqueous solution, containing the vanadate anion in the form of the sodium salt, the reaction affords, over a temperature range of 40 to 70 degrees C, selectively methyl hydroperoxide within 4 h. The yield of CH3OOH attains 24%, based on H2O2, after 24 h at 50 degrees C, the catalytic turnover number being 480. The process seems to involve hydroxyl radicals, generated by the catalyst from H2O2 even at low temperatures. At 120 degrees C, methane is oxidized by O-2 and H2O2 to give formaldehyde and formic acid, even in the absence of the catalyst, presumably due to the formation of HO radicals from H2O2 in the presence of very low concentrations of metal ions from the autoclave under high temperature conditions. (C) 1998 Elsevier Science B.V.