Vignette d'image

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

Résultat de la recherche

Filtres

23
221
Réinitialiser les filtres

Paramètres

Voici les éléments 1 - 10 sur 23
  • Publication
    Métadonnées seulement
    Vanadate ion-catalyzed oxidation of methane with hydrogen peroxide in an aqueous solution
    (2008)
    Romakh, Vladimir B
    ;
    Süss-Fink, Georg 
    ;
    Shul'pin, Georgiy B
    It was shown that, unlike methane oxidation with the reagent "hydrogen peroxide-vanadate anion-pyrazine-2-carboxylic acid (PCA)" in acetonitrile, the performance of the process in an aqueous solution is accompanied by the intense parallel degradation of the cocatalyst. Therefore, relatively high yields of methane oxidation products (largely, formic acid) cannot be attained unless a rather high PCA concentration is used. Admixtures of a strong acid (sulfuric, trifluoroacetic, or perchloric) increase the yield of the products. It was found that perchloric acid can also be used as a cocatalyst instead of PCA.
  • 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
    Regioselective alkane oxygenation with H2O2 catalyzed by titanosilicalite TS-1
    (2006)
    Shul'pin, Georgiy B
    ;
    Sooknoi, Tawan
    ;
    Romakh, Vladimir B
    ;
    Süss-Fink, Georg 
    ;
    Shul'pina, Lidia S
    Titanosilicalite TS-1 catalyses oxidation of light (methane, ethane, propane and n-butane) and normal higher (hexane, heptane, octane and nonane) alkanes to give the corresponding isomeric alcohols and ketones. The oxidation of higher alkanes proceeds in many cases with a unique regioselectivity. Thus, in the reaction with n-heptane the CH2 groups in position 3 exhibited a reactivity 2.5 times higher than those of the other methylene groups. This selectivity can be enhanced if hexan-3-ol is added to the reaction mixture, the 3-CH2/2-CH2 ratio becoming 10. It is assumed that the unusual selectivity in the oxidation of n-heptane (and other higher alkanes) is due to steric hindrance in the catalyst cavity. As a result, the catalytically active species situated on the catalyst walls can only easily react with certain methylenes of the alkane, which is adsorbed in the cavity taking U-shape (hairpin) conformations. (c) 2006 Elsevier Ltd. All rights reserved.
  • Publication
    Métadonnées seulement
    Alkane oxygenation with H2O2 catalysed by FeCl3 and 2,2 '-bipyridine
    (2005)
    Shul'pin, Georgiy B
    ;
    Golfeto, Camilla C
    ;
    Süss-Fink, Georg 
    ;
    Shul'pina, Lidia S
    ;
    Mandelli, Dalma
    The H2O2-FeCl3-bipy system in acetonitrile efficiently oxidises alkanes predominantly to alkyl hydroperoxides. Turnover numbers attain 400 after 1 h at 60 degrees C. It has been assumed that bipy facilitates proton abstraction from a H2O2 molecule coordinated to the iron ion (these reactions are stages in the catalytic cycle generating hydroxyl radicals from the hydrogen peroxide). Hydroxyl radicals then attack alkane molecules finally yielding the alkyl hydroperoxide. (c) 2005 Elsevier Ltd. All rights reserved.
  • Publication
    Métadonnées seulement
    Oxidation of saturated hydrocarbons with peroxides catalyzed by iridium and palladium complexes
    (2005)
    Shul'pina, Lidia S
    ;
    Kudinov, A R
    ;
    Süss-Fink, Georg 
    ;
    Loginov, D A
    ;
    Shul'pin, Georgiy B
  • 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
    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.
  • 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
    Hydrogen peroxide oxidation of saturated hydrocarbons catalyzed by osmium compounds
    (2002)
    Shul'pin, Georgiy B
    ;
    Süss-Fink, Georg 
    Osmium derivatives, in particular OsCl3, catalyze the effective oxidation of saturated hydrocarbons in acetonitrile. The products formed are a ketone (aldehyde) and an alcohol. The addition of nitrogen heterocycles, such as pyridine, accelerated the reaction and increased the product yields. The ketone (aldehyde)/alcohol ratio dramatically changed in this case. In the presence of pyridine, the reaction occurred stereoselectively. The suggested reaction mechanism includes hydrogen atom abstraction from an alkane by an osmium oxo compound, resulting in the formation of the alkyl radical, which yields the alkylperoxyl radical after addition of an oxygen molecule. The latter radical degrades in the presence of the osmium complex under reaction conditions to give a ketone (aldehyde) and an alcohol.
  • Publication
    Métadonnées seulement
    Hydrogen hydroperoxide oxidation of ethane and other alkanes catalyzed by chromium compounds
    (2002)
    Süss-Fink, Georg 
    ;
    Shul'pin, Georgiy B
    Chromium oxo derivatives (H2CrO4) catalyze the effective oxidation of ethane and other saturated hydrocarbons with hydrogen peroxide or tert-butyl hydroperoxide in an acetonitrile solution at 60degreesC. Alkyl hydroperoxides, ketones (aldehydes), and alcohols are formed as main products. The oxidation of ethane gives ethyl hydroperoxide, acetaldehyde, ethanol, and acetic acid. The turnover frequency reaches 620 h(-1) in this case, and the product yield in terms of H2O2 consumed is 21%.