Effects of solvation and ionization on 13C NMR spectra of lignin model compounds, spruce milled wood lignin and kraft lignin

A1 Journal article (refereed)


Internal Authors/Editors


Publication Details

List of Authors: Tatiana G. Fedulina, Muza F. Kiryushina, Sergey M. Shevchenko, Andrey V. Pranovich
Publisher: Taylor & Francis
Publication year: 2017
Journal: Journal of Wood Chemistry and Technology
Journal acronym: J. Wood Chem. Technol.
Volume number: 37
Issue number: 4
Start page: 241
End page: 250
Number of pages: 10
ISSN: 0277-3813
eISSN: 1532-2319


Abstract

The effects of alkali and polar aprotic solvent on the aromatic carbons signals in C-13 NMR (Carbon-13 nuclear magnetic resonance) spectra of lignin model compounds and spruce milled wood lignin (MWL) were studied. It was found that in 1M aqueous NaOH signal shifts of C-1 and C-4 carbon atoms in the aromatic ring were the most noticeable in lignin models with free phenolic hydroxyl groups, which are ionized under the conditions. A similar effect in the spectra of the studied model compounds was observed in 0.5M aqueous NaOD-deuterated dimethyl sulfoxide (DMSO) mixture (DMSO: water ratio 3:7 v/v). The model data help explaining changes in the C-13 NMR spectra of MWL and lignin in situ dissolved in spruce kraft black liquor caused by ionization. In the C-13 NMR spectra of spruce black liquor the signals of phenolic and non-phenolic lignin units are clearly separated and do not overlap with the signals of the carbon atoms of carbohydrates and other aliphatic products of wood degradation. The data obtained are useful in understanding the important role of solvation and ionization processes leading to lignin solubilization.


Keywords

aqueous alkali NMR, C-13 NMR, lignin model compounds, NaOD

Last updated on 2019-24-06 at 05:46