abstract
The structure of lignosulphonates (LS) from acidic magnesium-based sulphite pulping of Eucalyptus globulus wood has been studied. LS from thin and thick spent liquors were purified by dialysis and characterised by 1D/2D Nuclear Magnetic Resonance (NMR) and Electrospray Ionization Mass Spectrometry (ESI-MS). It was suggested that major part of LS is comprised of partially sulphonated low molecular weight oligomers formed via extensive cleavage of -O-4 bonds in eucalypt lignin upon sulphite pulping. More than ten types of LS structures derived from different lignin structural units have been identified. A significant proportion of LS ( 20%) is comprised by monomeric compounds, mainly 4-allyl-2,6-dimethoxyphenyl- -sulphonic and 4-propyl-2,6-dimethoxyphenyl-, -disulphonic acids. LS revealed partial degradation during the thin liquor evaporation leading to cleavage of ether and carbon-carbon linkages in the side chain and to the increasing of the condensation degree.
keywords
MASS-SPECTROMETRY; FINE CHEMICALS; LIGNIN; VANILLIN; BEHAVIOR
subject category
Materials Science
authors
Marques, AP; Evtuguin, DV; Magina, S; Amado, FML; Prates, A
our authors
Dmitry Evtyugin
Associate Professor with Aggregation
Sandra Pereira Magina
Researcheracknowledgements
This work was financially supported by the Foundation of the Science and the Technology (FCT), grant reference SFRH/BD/31463/2006, and by the innovation PRIME Program (grant SIME I&DT no. 00/22689).