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Please use this identifier to cite or link to this item: http://hdl.handle.net/10261/34790
Title: Structural characterization of milled wood lignin from different eucalypt species
Authors: Rencoret, Jorge ; Río Andrade, José Carlos del ; Marques, Gisela ; Gutiérrez Suárez, Ana ; Ibarra, David; Santos, José Ignacio; Jiménez-Barbero, Jesús; Martínez, Ángel T.
Keywords: Eucalypt wood
Milled-wood lignin (MWL)
Eucalyptus globulus
Eucalyptus nitens
Eucalyptus maidenii
Eucalyptus grandis
Eucalyptus dunnii
Issue Date: 2008
Publisher: Walter de Gruyter
Citation: Holzforschung 62: 514-526 (2008)
Abstract: The chemical structure of milled-wood lignins from Eucalyptus globulus, E. nitens, E. maidenii, E. grandis, and E. dunnii was investigated. The lignins were characterized by analytical pyrolysis, thioacidolysis and 2D-NMR that confirmed the predominance of syringyl over guaiacyl units and only showed traces of p-hydroxyphenyl units. E. globulus lignin had the highest syringyl content. The heteronuclear single quantum correlation (HSQC) NMR spectra gave information about relative abundances of inter-unit linkages in the whole polymer. All the lignins showed a predominance of β-O-4' ether linkages (66-72% of total side-chains), followed by β-β' resinol-type linkages (16-19%) and lower amounts of β-5' phenylcoumaran-type (3-7%) and β-1' spirodienone-type linkages (1-4%). The analysis of desulphurated thioacidolysis dimers provided additional information on the relative abundances of the various carbon-carbon and diaryl ether bonds, and the type of units (syringyl or guaiacyl) involved in each of the above linkage types. Interestingly, 93-94% of the total β-β' dimers included two syringyl units indicating that most of the β-β' substructures identified in the HSQC spectra were of the syringaresinol type. Moreover, three isomers of a major trimeric compound were found which were tentatively identified as arising from a β-β' syringaresinol substructure attached to a guaiacyl unit through a 4-O-5' linkage.
Description: Rencoret, Jorge et al.-- 13 pages, 7 figures, 6 tables, 49 references.
URI: http://hdl.handle.net/10261/34790
DOI: http://dx.doi.org/10.1515/HF.2008.096
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