Identification of a diagnostic structural motif reveals a new reaction intermediate and condensation pathway in kraft lignin formation
MetadataShow full item record
Altmetrics Handle Statistics
Altmetrics DOI Statistics
Kraft lignin, the main by-product of the pulping industry, is an abundant, yet highly underutilized renewable aromatic polymer. During kraft pulping, the lignin undergoes extensive structural modification, with many labile native bonds being replaced by new, more recalcitrant ones. Currently little is known about the nature of those bonds and linkages in kraft lignin, information that is essential for its efficient valorization to renewable fuels, materials or chemicals. Here, we provide detailed new insights into the structure of softwood kraft lignin, identifying and quantifying the major native as well as kraft pulping-derived units as a function of molecular weight. De novo synthetic kraft lignins, generated from (isotope labelled) dimeric and advanced polymeric models, provided key mechanistic understanding of kraft lignin formation, revealing different process dependent reaction pathways to be operating. The discovery of a novel kraft-derived lactone condensation product proved diagnostic for the identification of a previously unknown homovanillin based condensation pathway. The lactone marker is found in various different soft- and hardwood kraft lignins, suggesting the general pertinence of this new condensation mechanism for kraft pulping. These novel structural and mechanistic insights will aid the development of future biomass and lignin valorization technologies.
Lancefield , C S , Wienk , H L J , Boelens , R , Weckhuysen , B M & Bruijnincx , P C A 2018 , ' Identification of a diagnostic structural motif reveals a new reaction intermediate and condensation pathway in kraft lignin formation ' , Chemical Science , vol. 9 , no. 30 , pp. 6348-6360 . https://doi.org/10.1039/c8sc02000k
Copyright © 2018The Author(s). Open Access Article. This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence.
DescriptionThe authors gratefully acknowledge financial support of NWO, the Smart Mix Program of the Netherlands Ministry of Economic Affairs and the Netherlands Ministry of Education, Culture and Science. The NWO Large grant 175.107.301.10 is also gratefully acknowledged.
Items in the St Andrews Research Repository are protected by copyright, with all rights reserved, unless otherwise indicated.