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  • 1.
    Dawange, Monali
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
    Galkin, Maxim V.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
    Samec, Joseph S. M.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
    Selective Aerobic Benzylic Alcohol Oxidation of Lignin Model Compounds: Route to Aryl Ketones2015In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 7, no 3, p. 401-404Article in journal (Refereed)
    Abstract [en]

    A mild and chemoselective oxidation of the -alcohol in -O-4-ethanoaryl and -O-4-glycerolaryl ethers has been developed. The benzylic alcohols were selectively dehydrogenated to the corresponding ketones in 60-93% yield. A one-pot selective route to aryl ethyl ketones was performed. The catalytic system comprises recyclable heterogeneous palladium, mild reaction conditions, green solvents, and oxygen in air as oxidant. Catalytic amounts of a coordinating polyol were found pivotal for an efficient aerobic oxidation.

  • 2.
    Galkin, Maxim
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Synthetical Organic Chemistry.
    Palladium-catalyzed lignin valorization: Towards a lignin-based biorefinery2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The work described in this thesis focuses on the cleavage of the β-O-4′ bond, which is the most abundant interunit linkage in the lignin polymer.

    In the first part, three methods based on palladium catalysis have been developed and their applicability has been verified using lignin model compounds. A transfer hydrogenolysis of the β-O-4′ bond using formic acid as a mild hydrogen donor together with a base. An aerobic oxidation of the benzylic alcohol motif in the β-O-4′ linkage to generate a key intermediate in the cleavage reaction was performed. A redox neutral cleavage of the β-O-4′ bond was accomplished in which no stoichiometric reducing or oxidizing agents were added.

    In the second part of the thesis, a mechanistic study is presented. The corresponding ketone from a dehydrogenation reaction of the benzylic alcohol motif was identified to be the key intermediate. This ketone and its enol tautomer was found to be responsible for the β-O-4′ bond cleavage reaction under the employed reaction conditions.

    In the final part of this thesis, the methodologies have been applied to native lignin. The depolymerization reaction was combined with organosolv pulping. This approach was successful, and together with cellulose and hemicellulose, propenyl aryls were generated in excellent yields directly from wood. In this transformation, the lignin derived molecules have been reduced by an endogenous hydrogen donor from the wood.

    List of papers
    1. Mild Heterogeneous Palladium-Catalyzed Cleavage of beta-O-4 '-Ether Linkages of Lignin Model Compounds and Native Lignin in Air
    Open this publication in new window or tab >>Mild Heterogeneous Palladium-Catalyzed Cleavage of beta-O-4 '-Ether Linkages of Lignin Model Compounds and Native Lignin in Air
    Show others...
    2014 (English)In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 6, no 1, p. 179-184Article in journal (Refereed) Published
    Abstract [en]

    A mild and robust heterogeneous palladium-catalyzed CO bond cleavage of 2-aryloxy-1-arylethanols using formic acid as reducing agent in air was developed. The cleaved products were isolated in 92-98% yield; and by slightly varying the reaction conditions, a ketone, an alcohol, or an alkane can be generated in near-quantitative yield. This reaction is applicable to cleaving the -O-4-ether bond found in lignin polymers of different origin. The reaction was performed on a lignin polymer model to generate either the monomeric aryl ketone or alkane in a quantitative yield. Moderate depolymerization was achieved with native lignin at similar reaction conditions. Mechanistic studies under kinetic control indicate that an initial palladium-catalyzed dehydrogenation of the alcohol is followed by insertion of palladium to an enol equivalent. A palladium-formato complex reductively cleaves the palladium-enolate complex to generate the ketone.

    Keywords
    heterogeneous catalysis, cleavage reactions, green chemistry, palladium, polymers, lignin
    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:uu:diva-220309 (URN)10.1002/cctc.201300540 (DOI)000330636800023 ()
    Note

    De två första författarna delar första författarskapet.

    Available from: 2014-03-17 Created: 2014-03-12 Last updated: 2017-12-05Bibliographically approved
    2. Selective Aerobic Benzylic Alcohol Oxidation of Lignin Model Compounds: Route to Aryl Ketones
    Open this publication in new window or tab >>Selective Aerobic Benzylic Alcohol Oxidation of Lignin Model Compounds: Route to Aryl Ketones
    2015 (English)In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 7, no 3, p. 401-404Article in journal (Refereed) Published
    Abstract [en]

    A mild and chemoselective oxidation of the -alcohol in -O-4-ethanoaryl and -O-4-glycerolaryl ethers has been developed. The benzylic alcohols were selectively dehydrogenated to the corresponding ketones in 60-93% yield. A one-pot selective route to aryl ethyl ketones was performed. The catalytic system comprises recyclable heterogeneous palladium, mild reaction conditions, green solvents, and oxygen in air as oxidant. Catalytic amounts of a coordinating polyol were found pivotal for an efficient aerobic oxidation.

    Keywords
    biomass valorization, heterogeneous catalysis, lignin, oxidation, palladium
    National Category
    Chemical Sciences
    Identifiers
    urn:nbn:se:uu:diva-246820 (URN)10.1002/cctc.201402825 (DOI)000349147100005 ()
    Available from: 2015-03-11 Created: 2015-03-10 Last updated: 2017-12-04Bibliographically approved
    3. Mild and Robust Redox-Neutral Pd/C-Catalyzed Lignol -O-4 Bond Cleavage Through a Low-Energy-Barrier Pathway
    Open this publication in new window or tab >>Mild and Robust Redox-Neutral Pd/C-Catalyzed Lignol -O-4 Bond Cleavage Through a Low-Energy-Barrier Pathway
    2015 (English)In: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 8, no 13, p. 2187-2192Article in journal (Refereed) Published
    Abstract [en]

    A Pd/C catalyzed redox neutral CO bond cleavage of 2-aryloxy-1-arylethanols has been developed. The reactions are carried out at 80 degrees C, in air, using a green solvent system to yield the aryl ketones in near quantitative yields. Addition of catalytic amounts of a hydrogen source to the reaction mixture activates the catalyst to proceed through a low energy barrier pathway. Initial studies support a transfer hydrogenolysis reaction mechanism that proceeds through an initial dehydrogenation followed by an enol adsorption to Pd/C and a reductive CO bond cleavage.

    Keywords
    heterogeneous catalysis, lignin, palladium, reaction mechanisms, transfer hydrogenolysis
    National Category
    Chemical Sciences
    Identifiers
    urn:nbn:se:uu:diva-259649 (URN)10.1002/cssc.201500117 (DOI)000357619000004 ()25925736 (PubMedID)
    Funder
    Swedish Energy Agency
    Available from: 2015-08-20 Created: 2015-08-10 Last updated: 2017-12-04Bibliographically approved
    4. Selective Route to 2-Propenyl Aryls Directly from Wood by a Tandem Organosolv and Palladium-Catalysed Transfer Hydrogenolysis
    Open this publication in new window or tab >>Selective Route to 2-Propenyl Aryls Directly from Wood by a Tandem Organosolv and Palladium-Catalysed Transfer Hydrogenolysis
    2014 (English)In: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 7, no 8, p. 2154-2158Article in journal (Refereed) Published
    Abstract [en]

    A tandem organosolv pulping and Pd-catalysed transfer hydrogenolysis depolymerisation and deoxygenation has been developed. The tandem process generated 2-methoxy-4-(prop-1-enyl)phenol in 23 % yield (92 % theoretical monomer yield) starting from pine wood and 2,6-dimethoxy-4-(prop-1-enyl)phenol in 49 % yield (92 % theoretical monomer yield) starting from birch wood. Only endogenous hydrogen from wood was consumed, and the reaction was performed using green solvents.

    Keywords
    Biomass, Lignin Green, Chemistry, Palladium, catalysis
    National Category
    Organic Chemistry
    Research subject
    Chemistry with specialization in Organic Chemistry
    Identifiers
    urn:nbn:se:uu:diva-226637 (URN)10.1002/cssc.201402017 (DOI)000340519500016 ()
    Funder
    Swedish Energy Agency
    Available from: 2014-06-18 Created: 2014-06-18 Last updated: 2017-12-05Bibliographically approved
  • 3.
    Galkin, Maxim
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Synthetical Organic Chemistry.
    Samec, Joseph
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Synthetical Organic Chemistry.
    Selective Route to 2-Propenyl Aryls Directly from Wood by a Tandem Organosolv and Palladium-Catalysed Transfer Hydrogenolysis2014In: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 7, no 8, p. 2154-2158Article in journal (Refereed)
    Abstract [en]

    A tandem organosolv pulping and Pd-catalysed transfer hydrogenolysis depolymerisation and deoxygenation has been developed. The tandem process generated 2-methoxy-4-(prop-1-enyl)phenol in 23 % yield (92 % theoretical monomer yield) starting from pine wood and 2,6-dimethoxy-4-(prop-1-enyl)phenol in 49 % yield (92 % theoretical monomer yield) starting from birch wood. Only endogenous hydrogen from wood was consumed, and the reaction was performed using green solvents.

  • 4.
    Galkin, Maxim V.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
    Dahlstrand, Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
    Samec, Joseph S. M.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
    Mild and Robust Redox-Neutral Pd/C-Catalyzed Lignol -O-4 Bond Cleavage Through a Low-Energy-Barrier Pathway2015In: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 8, no 13, p. 2187-2192Article in journal (Refereed)
    Abstract [en]

    A Pd/C catalyzed redox neutral CO bond cleavage of 2-aryloxy-1-arylethanols has been developed. The reactions are carried out at 80 degrees C, in air, using a green solvent system to yield the aryl ketones in near quantitative yields. Addition of catalytic amounts of a hydrogen source to the reaction mixture activates the catalyst to proceed through a low energy barrier pathway. Initial studies support a transfer hydrogenolysis reaction mechanism that proceeds through an initial dehydrogenation followed by an enol adsorption to Pd/C and a reductive CO bond cleavage.

  • 5.
    Galkin, Maxim V.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Synthetical Organic Chemistry.
    Sawadjoon, Supaporn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Synthetical Organic Chemistry.
    Rohde, Volker
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Synthetical Organic Chemistry.
    Dawange, Monali
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Synthetical Organic Chemistry.
    Samec, Joseph S. M.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Synthetical Organic Chemistry.
    Mild Heterogeneous Palladium-Catalyzed Cleavage of beta-O-4 '-Ether Linkages of Lignin Model Compounds and Native Lignin in Air2014In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 6, no 1, p. 179-184Article in journal (Refereed)
    Abstract [en]

    A mild and robust heterogeneous palladium-catalyzed CO bond cleavage of 2-aryloxy-1-arylethanols using formic acid as reducing agent in air was developed. The cleaved products were isolated in 92-98% yield; and by slightly varying the reaction conditions, a ketone, an alcohol, or an alkane can be generated in near-quantitative yield. This reaction is applicable to cleaving the -O-4-ether bond found in lignin polymers of different origin. The reaction was performed on a lignin polymer model to generate either the monomeric aryl ketone or alkane in a quantitative yield. Moderate depolymerization was achieved with native lignin at similar reaction conditions. Mechanistic studies under kinetic control indicate that an initial palladium-catalyzed dehydrogenation of the alcohol is followed by insertion of palladium to an enol equivalent. A palladium-formato complex reductively cleaves the palladium-enolate complex to generate the ketone.

  • 6.
    Galkin, Maxim V.
    et al.
    Stockholm Univ, Dept Organ Chem, S-10691 Stockholm, Sweden..
    Smit, Arjan T.
    Energy Res Ctr Netherlands ECN, Biomass & Energy Efficiency, Westerduinweg 3, NL-1755 LE Petten, Netherlands..
    Subbotina, Elena
    Stockholm Univ, Dept Organ Chem, S-10691 Stockholm, Sweden..
    Artemenko, Konstantin A.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Analytical Chemistry.
    Bergquist, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Analytical Chemistry.
    Huijgen, Wouter J. J.
    Energy Res Ctr Netherlands ECN, Biomass & Energy Efficiency, Westerduinweg 3, NL-1755 LE Petten, Netherlands..
    Samec, Joseph S. M.
    Stockholm Univ, Dept Organ Chem, S-10691 Stockholm, Sweden..
    Hydrogen-free catalytic fractionation of woody biomass2016In: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 9, no 23, p. 3280-3287Article in journal (Refereed)
    Abstract [en]

    The pulping industry could become a biorefinery if the lignin and hemicellulose components of the lignocellulose are valorized. Conversion of lignin into well-defined aromatic chemicals is still a major challenge. Lignin depolymerization reactions often occur in parallel with irreversible condensation reactions of the formed fragments. Here, we describe a strategy that markedly suppresses the undesired condensation pathways and allows to selectively transform lignin into a few aromatic compounds. Notably, applying this strategy to woody biomass at organosolv pulping conditions, the hemicellulose, cellulose, and lignin were separated and in parallel the lignin was transformed into aromatic monomers. In addition, we were able to utilize a part of the lignocellulose as an internal source of hydrogen for the reductive lignin transformations. We hope that the presented methodology will inspire researchers in the field of lignin valorization as well as pulp producers to develop more efficient biomass fractionation processes in the future.

  • 7.
    Kumaniaev, Ivan
    et al.
    Stockholm University, Department of Organic Chemistry.
    Subbotina, Elena
    Stockholm University, Department of Organic Chemistry.
    Sävmarker, Jonas
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Organic Pharmaceutical Chemistry. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Larhed, Mats
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Organic Pharmaceutical Chemistry. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Galkin, Maxim V.
    Stockholm University, Department of Organic Chemistry.
    Samec, Joseph S. M.
    Stockholm University, Department of Organic Chemistry.
    Lignin depolymerization to monophenolic compounds in a flow-through system2017In: Green Chemistry, ISSN 1463-9262, E-ISSN 1463-9270, Vol. 19, no 24, p. 5767-5771Article in journal (Refereed)
    Abstract [en]

    A reductive lignocellulose fractionation in a flow-through system in which pulping and transfer hydrogenolysis steps were separated in time and space has been developed. Without the hydrogenolysis step or addition of trapping agents to the pulping, it is possible to obtain partially depolymerized lignin (21 wt% monophenolic compounds) that is prone to further processing. By applying a transfer hydrogenolysis step 37 wt% yield of lignin derived monophenolic compounds was obtained. Pulp generated in the process was enzymatically hydrolyzed to glucose in 87 wt% yield without prior purification.

  • 8.
    Sawadjoon, Supaporn
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Synthetical Organic Chemistry.
    Galkin, Maxim
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Synthetical Organic Chemistry.
    Dahlstrand, Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
    Rohde, Volker
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
    Samec, Joseph S. M.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Synthetical Organic Chemistry.
    Selective palladium-catalyzed reductive cleavage of beta-O-4-glucolaryl ether linkages in lignin model compounds2013In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 245, p. 15-ORGN-Article in journal (Other academic)
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