Purification, Structural Characterization, and Modification of Organosolv Wheat Straw Lignin

Biolignin, a wheat straw lignin produced by acetic acid/formic acid/water hydrolysis, was characterized by 31P and 13C–1H 2D NMR spectroscopy and by size-exclusion chromatography. Biolignin is a mixture of low molar mass compounds (M n = 1660 g/mol) made up of S, G, and H units and of coumaric and f...

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Bibliographic Details
Published in:Journal of agricultural and food chemistry 2015-06, Vol.63 (21), p.5178-5188
Main Authors: Mbotchak, Laurie, Le Morvan, Clara, Duong, Khanh Linh, Rousseau, Brigitte, Tessier, Martine, Fradet, Alain
Format: Article
Language:English
Subjects:
acetates
acetic acid
alkaline hydrolysis
Chemical Sciences
Chromatography, Gel
esterification
ethanol
ferulic acid
formic acid
gel chromatography
Hydrolysis
lignin
Lignin - chemistry
Lignin - isolation & purification
Magnetic Resonance Spectroscopy
Molecular Structure
Molecular Weight
nuclear magnetic resonance spectroscopy
phenol
Plant Extracts - chemistry
Plant Extracts - isolation & purification
Plant Stems - chemistry
solvents
Triticum - chemistry
wheat straw
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Summary:Biolignin, a wheat straw lignin produced by acetic acid/formic acid/water hydrolysis, was characterized by 31P and 13C–1H 2D NMR spectroscopy and by size-exclusion chromatography. Biolignin is a mixture of low molar mass compounds (M n = 1660 g/mol) made up of S, G, and H units and of coumaric and ferulic acid units. β-5 and β-O-4 interunit linkages are partially acylated in the γ-position by acetate and p-coumarate groups. Deacylated samples with a low content of contaminants were obtained by combining alkaline hydrolysis and solvent extraction. The high phenolic OH content found by 31P NMR reflects the presence of condensed aromatic units, such as 5–5 units. Reaction of purified lignin with ethanol and ethane-1,2-diol yielded esterified lignins much more soluble than Biolignin in common organic solvents. During this reaction, the secondary OH of β-O-4 linkages was simultaneously etherified. Phenol hydroxyethylation by 2-chloroethanol yielded samples containing only aliphatic hydroxyl groups.
ISSN:0021-8561
1520-5118
DOI:10.1021/acs.jafc.5b02071