NMR Assignment for Diaryl Ether Structures (4-O-5 Structures) in Pine Wood Lignin
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Updated: Mar 22, 2026

Extraction of Lignin with High β-O-4 Content by Mild Ethanol Extraction and Its Effect on the Depolymerization Yield
Published on: January 7, 2019
Yanding Li1, Takuya Akiyama1,2, Tomoya Yokoyama1
1Wood Chemistry Laboratory, Department of Biomaterial Sciences, Graduate School of Agricultural and Life Sciences, The University of Tokyo , Bunkyo-ku, Tokyo 113-8657, Japan.
Abstract:
A 4-O-5-tetramer lignin model compound carrying β-O-4 linkages on each of the side-chain moieties was synthesized, as well as 4-O-5-coupled dehydrodiconiferyl alcohol. By comparison with their NMR data, two cross-signals in the HSQC spectrum of pine milled wood lignin recorded in DMSO-d6 were assigned to H2/C2 and H6/C6 correlations on the aromatic rings of 4-O-5-linked units. Although the H2/C2 correlation peak appeared in the same region as syringyl units, nitrobenzene oxidation of the pine lignin did not yield any syringyl-type product, but did release a 4-O-5-type product.
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