Ewellyn A. Capanema, Mikhail Yu Balakshin, Chen-Loung Chen, Josef S. Gratzl, Hanna Gracz
Structural Analysis of Residual and Technical Lignins by 1H-13C Correlation 2D NMR-Spectroscopy
Summary
Structural analysis was conducted on residual lignin from pine Kraft AQ pulp, Eucalyptus Kraft lignin
from Eucalyptus globulus and Repap Organosolv lignin by 2D 13C-1H correlation NMR spectroscopic
techniques such as HMQC sequence. These lignins contain a rather wide variety of saturated aliphatic
groups. The HMQC NMR spectra of the lignins do not verify the presence of diarylmethane moieties in
any lignin investigated. The type and amount of other condensed structures depend on the nature of lignin
preparation. All the lignins investigated still contained ?-O-4?, pino- and syringayresinol (?-??) and
phenylcoumarane (?-5?) structures. Stilbene structures were also identified. Vinyl ether structures were
present only in Eucalyptus Kraft lignin. All the lignins contain ?-carbonyl groups conjugated to aromatic
moieties as terminal side chains rather than involving ?-O-4? structures. No coniferyl alcohol and
coniferyl aldehyde type structures are detected in the lignins after pulping. The spectra of kraft lignins
show some new signals, the origin of which is discussed.
Holzforschung, Walter de Gruyter
Print ISSN: 0018-3830
Volume: 55, 04/2001
Pages: 302 - 308
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