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Polyoxometalate (POM) oxidation of lignin model compounds

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Published/Copyright: December 5, 2007
Holzforschung
From the journal Volume 62 Issue 1

Abstract

Various lignin model compounds were oxidized with polyoxometalate (POM), K5[SiVW11O40]·12 H2O, in sodium acetate buffer (I=0.2 M, pH 5.0) and the reaction kinetics were investigated. The reactions were found to have second order reaction rates, first order with regards to both lignin model compound and POM. A dramatic increase in reactivity was observed upon addition of methoxyl groups in ortho-positions to the phenolic hydroxyl group. Syringyl units reacted faster than guaiacyl units. Reaction rates of para-substituted guaiacyl and syringyl model compounds showed a strong dependency on the nature of the substituents. The reaction rate of a 5-5′ dimer lignin model compound was extremely fast. The addition of the ortho-phenol substituent not only increased the electron density of the aromatic ring, but also helped stabilize the intermediate phenoxy radical through resonance stabilization and delocalization.

Keywords: kinetics; lignin model compounds; oxidation; polyoxometalate (POM)
Corresponding author. Biomaterials Chemistry, Faculty of Forestry, University of British Columbia, Vancouver, BC, Canada Phone: +1-604-822-5254, Fax: +1-604-822-9104,
Received: 2007-5-1
Accepted: 2007-8-6
Published Online: 2007-12-05
Published in Print: 2008-1-1

©2008 by Walter de Gruyter Berlin New York

Articles in the same Issue

  1. Meetings
  2. Evaluation of Eucalyptus grandis Hill ex Maiden biopulping with Ceriporiopsis subvermispora under non-aseptic conditions
  3. Paper dry strength improvement by xyloglucan addition: Wet-end application, spray coating and synergism with borate
  4. A new and facile method for isolation of lignin from wood based on complete wood dissolution
  5. Isolation and characterization of lignins from Eucalyptus grandis Hill ex Maiden and Eucalyptus globulus Labill. by enzymatic mild acidolysis (EMAL)
  6. Fractionation and characterization of xylan rich extracts from birch
  7. Polyoxometalate (POM) oxidation of lignin model compounds
  8. Pyrolytic cleavage mechanisms of lignin-ether linkages: A study on p-substituted dimers and trimers
  9. Polysaccharide degradation in waterlogged oak wood from the ancient warship Vasa
  10. Degradation of polyethylene glycol and hemicellulose in the Vasa
  11. Selection criteria of Eucalyptus globulus Labill. for production of chemithermomechanical pulps (CTMP)
  12. The effect of (induced) dislocations on the tensile properties of individual Norway spruce fibres
  13. Mode I and Mode II fracture toughness of densified Sitka spruce fabricated in an airtight atmosphere with high-temperature steam
  14. Characteristic properties of embedding strength for the nailing of the gonfolo rose (Qualea rosea Aubl.)
  15. Adhesive penetration of wood cell walls investigated by scanning thermal microscopy (SThM)
  16. Laboratory screening of tropical hardwoods for natural resistance to the marine borer Limnoria quadripunctata: The role of leachable and non-leachable factors
  17. Decay resistance of wood treated with amino-silicone compounds
  18. Hydrothermal treatment of mixed preservative-treated wood waste
  19. Variation of tracheid length within annual rings of Scots pine and Norway spruce
https://doi.org/10.1515/HF.2008.006
Keywords for this article
kinetics; lignin model compounds; oxidation; polyoxometalate (POM)

Articles in the same Issue

  1. Meetings
  2. Evaluation of Eucalyptus grandis Hill ex Maiden biopulping with Ceriporiopsis subvermispora under non-aseptic conditions
  3. Paper dry strength improvement by xyloglucan addition: Wet-end application, spray coating and synergism with borate
  4. A new and facile method for isolation of lignin from wood based on complete wood dissolution
  5. Isolation and characterization of lignins from Eucalyptus grandis Hill ex Maiden and Eucalyptus globulus Labill. by enzymatic mild acidolysis (EMAL)
  6. Fractionation and characterization of xylan rich extracts from birch
  7. Polyoxometalate (POM) oxidation of lignin model compounds
  8. Pyrolytic cleavage mechanisms of lignin-ether linkages: A study on p-substituted dimers and trimers
  9. Polysaccharide degradation in waterlogged oak wood from the ancient warship Vasa
  10. Degradation of polyethylene glycol and hemicellulose in the Vasa
  11. Selection criteria of Eucalyptus globulus Labill. for production of chemithermomechanical pulps (CTMP)
  12. The effect of (induced) dislocations on the tensile properties of individual Norway spruce fibres
  13. Mode I and Mode II fracture toughness of densified Sitka spruce fabricated in an airtight atmosphere with high-temperature steam
  14. Characteristic properties of embedding strength for the nailing of the gonfolo rose (Qualea rosea Aubl.)
  15. Adhesive penetration of wood cell walls investigated by scanning thermal microscopy (SThM)
  16. Laboratory screening of tropical hardwoods for natural resistance to the marine borer Limnoria quadripunctata: The role of leachable and non-leachable factors
  17. Decay resistance of wood treated with amino-silicone compounds
  18. Hydrothermal treatment of mixed preservative-treated wood waste
  19. Variation of tracheid length within annual rings of Scots pine and Norway spruce
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