Structural characterization of milled wood lignins from different eucalypt species
2008 (English)In: Holzforschung, ISSN 0018-3830, Vol. 62, no 5, 514-526 p.Article in journal (Refereed) Published
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 yielded information about relative abundances of inter-unit linkages in the whole polymer. All the lignins showed a predominance of beta-O-4' ether linkages (66-72% of total side-chains), followed by beta-beta' resinol-type linkages (16-19%) and lower amounts of beta-5' phenylcoumarin-type (3-7%) and beta-1' spirodienone-type linkages (1-4%). The analysis of desulfurated 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 beta-beta' dimers included two syringyl units indicating that most of the beta-beta' 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 beta-beta' syringaresinol substructure attached to a guaiacyl unit through a 4-O-5' linkage.
Place, publisher, year, edition, pages
2008. Vol. 62, no 5, 514-526 p.
2D-NMR, desulfuration, dimers, eucalypt wood, Eucalyptus dunnii, Eucalyptus globulus, Eucalyptus grandis, Eucalyptus maidenii, Eucalyptus nitens, heteronuclear single quantum correlation (HSQC), milledwood lignin (MWL), pyrolysis-GC/MS, thioacidolysis, trimers, pyrolysis-gas chromatography, nuclear-magnetic-resonance, nmr-spectroscopy, chemical-structure, technical lignins, hardwood, lignins, tree variation, py-gc/ms, globulus, delignification
IdentifiersURN: urn:nbn:se:kth:diva-17799DOI: 10.1515/hf.2008.096ISI: 000258963400004ScopusID: 2-s2.0-48649085851OAI: oai:DiVA.org:kth-17799DiVA: diva2:335844
QC 201005252010-08-052010-08-05Bibliographically approved