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Yu. S. Demidova - One of the best experts on this subject based on the ideXlab platform.

  • Hydrogenation of (–)-Carvone in Presence of Gold Catalysts: Role of the Support
    Catalysis in Industry, 2018
    Co-Authors: Yu. S. Demidova, Andrey Simakov, I.l. Simakova, D. Yu. Murzin
    Abstract:

    The liquid phase hydrogenation of biomass derived (–)-carvone into industrially valuable Dihydrocarvone was studied over monometallic Au catalysts supported on alumina, titania and zirconia, as well as on the mesoporous carbon support Sibunit in methanol as a solvent (100°C, hydrogen pressure 9 bar). It was shown that among the three types of functional groups present in carvone, which can be hydrogenated, namely C=O, conjugated and isolated C=C groups, hydrogenation of the latter was predominant. The catalytic activity was found to depend on the catalyst support type. Under comparative reaction conditions, the carvone conversion increased in the following sequence: Au/C ≪Au/ZrO2 < Au/Al2O3 ≪Au/TiO2. A higher activity of Au catalysts over metal oxides as compared to Au/C can be caused by the presence of acid sites as well as oxygen vacancies in their structure allowing strong adsorption of carvone through its carbonyl moiety. All catalysts supported on oxides showed similar selectivity towards trans- and cis-Dihydrocarvone with the ratio between isomers (trans-/cis-isomer) being about 1.8, while this value for Au/C was close to 3.9, which can be related to a much lower carvone conversion in the latter case.

  • Selective one-pot carvone oxime hydrogenation over titania supported gold catalyst as a novel approach for Dihydrocarvone synthesis
    Journal of Molecular Catalysis A: Chemical, 2016
    Co-Authors: Yu. S. Demidova, I.l. Simakova, E. V. Suslov, Olga A. Simakova, Konstantin P. Volcho, N.f. Salakhutdinov, D. Yu. Murzin
    Abstract:

    Abstract It was shown for the first time that Dihydrocarvone can be selectively produced by gold-catalyzed one-pot transformation of carvone oxime. This reaction was carried out at 100 °C under hydrogen pressure of 9 bar over 1.9 wt.% Au/TiO2 catalyst using methanol as a solvent. Dihydrocarvone synthesis was shown to occur via carvone formation with the subsequent hydrogenation of its conjugated C C double bond. Application of Au/TiO2 catalyst for both deoximation and selective hydrogenation of olefinic C C functional group is reported for the first time. The combination of these steps provides optimization of the synthetic method for Dihydrocarvone production from carvone oxime which is a key intermediate in carvone synthesis from limonene. Despite a lower reaction rate than in the case of carvone, a significant increase in the stereoselectivity towards trans-Dihydrocarvone was observed in the case of carvone oxime hydrogenation. The ratio between trans- and cis-Dihydrocarvone was close to 4.0 compared to 1.8 achieved in the case of carvone hydrogenation.

  • selective carvone hydrogenation to Dihydrocarvone over titania supported gold catalyst
    Catalysis Today, 2015
    Co-Authors: Yu. S. Demidova, I.l. Simakova, E. V. Suslov, Olga A. Simakova, Konstantin P. Volcho, N.f. Salakhutdinov, Yu D Murzin
    Abstract:

    Abstract Selective hydrogenation of natural carvone to industrially valuable Dihydrocarvone was carried out at 100 °C under hydrogen pressure over a 1.9 wt.% Au/TiO2 catalyst. The gold catalyst has demonstrated high activity as well as stereo- and chemoselectivity in conjugated C C double bond hydrogenation with predominant formation of trans-Dihydrocarvone. The catalytic activity and trans- to cis-isomers ratio were shown to strongly depend on the solvent. In a range of C1 C3 alcohol solvents both catalytic activity and trans- to cis-Dihydrocarvone ratio increased following the order: 2-propanol

Olga A. Simakova - One of the best experts on this subject based on the ideXlab platform.

  • Selective one-pot carvone oxime hydrogenation over titania supported gold catalyst as a novel approach for Dihydrocarvone synthesis
    Journal of Molecular Catalysis A: Chemical, 2016
    Co-Authors: Yu. S. Demidova, I.l. Simakova, E. V. Suslov, Olga A. Simakova, Konstantin P. Volcho, N.f. Salakhutdinov, D. Yu. Murzin
    Abstract:

    Abstract It was shown for the first time that Dihydrocarvone can be selectively produced by gold-catalyzed one-pot transformation of carvone oxime. This reaction was carried out at 100 °C under hydrogen pressure of 9 bar over 1.9 wt.% Au/TiO2 catalyst using methanol as a solvent. Dihydrocarvone synthesis was shown to occur via carvone formation with the subsequent hydrogenation of its conjugated C C double bond. Application of Au/TiO2 catalyst for both deoximation and selective hydrogenation of olefinic C C functional group is reported for the first time. The combination of these steps provides optimization of the synthetic method for Dihydrocarvone production from carvone oxime which is a key intermediate in carvone synthesis from limonene. Despite a lower reaction rate than in the case of carvone, a significant increase in the stereoselectivity towards trans-Dihydrocarvone was observed in the case of carvone oxime hydrogenation. The ratio between trans- and cis-Dihydrocarvone was close to 4.0 compared to 1.8 achieved in the case of carvone hydrogenation.

  • selective carvone hydrogenation to Dihydrocarvone over titania supported gold catalyst
    Catalysis Today, 2015
    Co-Authors: Yu. S. Demidova, I.l. Simakova, E. V. Suslov, Olga A. Simakova, Konstantin P. Volcho, N.f. Salakhutdinov, Yu D Murzin
    Abstract:

    Abstract Selective hydrogenation of natural carvone to industrially valuable Dihydrocarvone was carried out at 100 °C under hydrogen pressure over a 1.9 wt.% Au/TiO2 catalyst. The gold catalyst has demonstrated high activity as well as stereo- and chemoselectivity in conjugated C C double bond hydrogenation with predominant formation of trans-Dihydrocarvone. The catalytic activity and trans- to cis-isomers ratio were shown to strongly depend on the solvent. In a range of C1 C3 alcohol solvents both catalytic activity and trans- to cis-Dihydrocarvone ratio increased following the order: 2-propanol

Prakash Gopinath - One of the best experts on this subject based on the ideXlab platform.

  • triphase catalytic activity of a new insoluble multi site phase transfer catalyst in c alkylation of Dihydrocarvone a kinetic study
    Journal of Molecular Catalysis A-chemical, 2009
    Co-Authors: Eagambaram Murugan, Prakash Gopinath
    Abstract:

    Abstract A new insoluble multi-site triphase catalyst viz., polymer-supported 1,3,4-tris(triethylammoniummethylene chloride)-2-methylbenzene (PSTTACMB) containing three active sites was synthesized by simplified procedure and its structure was characterized by FT-IR, solid 13C NMR, TGA, [chloride ion] and SEM analyses. The catalytic efficiency of PSTTACMB was ascertained by comparing with insoluble single-site PTC viz., polymer-supported benzyltriethylammonium chloride (PSBTEAC) through determination of pseudo-first order rate constant for C-alkylation of Dihydrocarvone with 1-bromobutane using 25% (w/w) NaOH at 60 °C under identical experimental conditions. Further, the dependency of rate of C-alkylation of Dihydrocarvone on different kinetic variables was studied by varying the stirring speed, [substrate], [catalyst], [NaOH] and temperature. Based on the observed kinetic results and activation energy, a suitable mechanism was proposed.

  • Triphase catalytic activity of a new insoluble multi-site phase transfer catalyst in C-alkylation of Dihydrocarvone—A kinetic study
    Journal of Molecular Catalysis A-chemical, 2009
    Co-Authors: Eagambaram Murugan, Prakash Gopinath
    Abstract:

    Abstract A new insoluble multi-site triphase catalyst viz., polymer-supported 1,3,4-tris(triethylammoniummethylene chloride)-2-methylbenzene (PSTTACMB) containing three active sites was synthesized by simplified procedure and its structure was characterized by FT-IR, solid 13C NMR, TGA, [chloride ion] and SEM analyses. The catalytic efficiency of PSTTACMB was ascertained by comparing with insoluble single-site PTC viz., polymer-supported benzyltriethylammonium chloride (PSBTEAC) through determination of pseudo-first order rate constant for C-alkylation of Dihydrocarvone with 1-bromobutane using 25% (w/w) NaOH at 60 °C under identical experimental conditions. Further, the dependency of rate of C-alkylation of Dihydrocarvone on different kinetic variables was studied by varying the stirring speed, [substrate], [catalyst], [NaOH] and temperature. Based on the observed kinetic results and activation energy, a suitable mechanism was proposed.

Yu D Murzin - One of the best experts on this subject based on the ideXlab platform.

  • selective carvone hydrogenation to Dihydrocarvone over titania supported gold catalyst
    Catalysis Today, 2015
    Co-Authors: Yu. S. Demidova, I.l. Simakova, E. V. Suslov, Olga A. Simakova, Konstantin P. Volcho, N.f. Salakhutdinov, Yu D Murzin
    Abstract:

    Abstract Selective hydrogenation of natural carvone to industrially valuable Dihydrocarvone was carried out at 100 °C under hydrogen pressure over a 1.9 wt.% Au/TiO2 catalyst. The gold catalyst has demonstrated high activity as well as stereo- and chemoselectivity in conjugated C C double bond hydrogenation with predominant formation of trans-Dihydrocarvone. The catalytic activity and trans- to cis-isomers ratio were shown to strongly depend on the solvent. In a range of C1 C3 alcohol solvents both catalytic activity and trans- to cis-Dihydrocarvone ratio increased following the order: 2-propanol

I.l. Simakova - One of the best experts on this subject based on the ideXlab platform.

  • Hydrogenation of (–)-Carvone in Presence of Gold Catalysts: Role of the Support
    Catalysis in Industry, 2018
    Co-Authors: Yu. S. Demidova, Andrey Simakov, I.l. Simakova, D. Yu. Murzin
    Abstract:

    The liquid phase hydrogenation of biomass derived (–)-carvone into industrially valuable Dihydrocarvone was studied over monometallic Au catalysts supported on alumina, titania and zirconia, as well as on the mesoporous carbon support Sibunit in methanol as a solvent (100°C, hydrogen pressure 9 bar). It was shown that among the three types of functional groups present in carvone, which can be hydrogenated, namely C=O, conjugated and isolated C=C groups, hydrogenation of the latter was predominant. The catalytic activity was found to depend on the catalyst support type. Under comparative reaction conditions, the carvone conversion increased in the following sequence: Au/C ≪Au/ZrO2 < Au/Al2O3 ≪Au/TiO2. A higher activity of Au catalysts over metal oxides as compared to Au/C can be caused by the presence of acid sites as well as oxygen vacancies in their structure allowing strong adsorption of carvone through its carbonyl moiety. All catalysts supported on oxides showed similar selectivity towards trans- and cis-Dihydrocarvone with the ratio between isomers (trans-/cis-isomer) being about 1.8, while this value for Au/C was close to 3.9, which can be related to a much lower carvone conversion in the latter case.

  • Selective one-pot carvone oxime hydrogenation over titania supported gold catalyst as a novel approach for Dihydrocarvone synthesis
    Journal of Molecular Catalysis A: Chemical, 2016
    Co-Authors: Yu. S. Demidova, I.l. Simakova, E. V. Suslov, Olga A. Simakova, Konstantin P. Volcho, N.f. Salakhutdinov, D. Yu. Murzin
    Abstract:

    Abstract It was shown for the first time that Dihydrocarvone can be selectively produced by gold-catalyzed one-pot transformation of carvone oxime. This reaction was carried out at 100 °C under hydrogen pressure of 9 bar over 1.9 wt.% Au/TiO2 catalyst using methanol as a solvent. Dihydrocarvone synthesis was shown to occur via carvone formation with the subsequent hydrogenation of its conjugated C C double bond. Application of Au/TiO2 catalyst for both deoximation and selective hydrogenation of olefinic C C functional group is reported for the first time. The combination of these steps provides optimization of the synthetic method for Dihydrocarvone production from carvone oxime which is a key intermediate in carvone synthesis from limonene. Despite a lower reaction rate than in the case of carvone, a significant increase in the stereoselectivity towards trans-Dihydrocarvone was observed in the case of carvone oxime hydrogenation. The ratio between trans- and cis-Dihydrocarvone was close to 4.0 compared to 1.8 achieved in the case of carvone hydrogenation.

  • selective carvone hydrogenation to Dihydrocarvone over titania supported gold catalyst
    Catalysis Today, 2015
    Co-Authors: Yu. S. Demidova, I.l. Simakova, E. V. Suslov, Olga A. Simakova, Konstantin P. Volcho, N.f. Salakhutdinov, Yu D Murzin
    Abstract:

    Abstract Selective hydrogenation of natural carvone to industrially valuable Dihydrocarvone was carried out at 100 °C under hydrogen pressure over a 1.9 wt.% Au/TiO2 catalyst. The gold catalyst has demonstrated high activity as well as stereo- and chemoselectivity in conjugated C C double bond hydrogenation with predominant formation of trans-Dihydrocarvone. The catalytic activity and trans- to cis-isomers ratio were shown to strongly depend on the solvent. In a range of C1 C3 alcohol solvents both catalytic activity and trans- to cis-Dihydrocarvone ratio increased following the order: 2-propanol