Pd/C promotes C–H bond activation and oxidation of p-hydroxybenzoate during hydrogenolysis of poplar

Abstract Hydrogenolysis of lignin generates a portfolio of products, the yields of which are generally calculated using a subset of phenolic monomers that are dependent on the lignin composition, product distribution, and analytical technique. Some lignins are naturally γ-acylated; poplar lignins, f...

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Main Authors: Canan Sener, Vitaliy I. Timokhin, Jan Hellinger, John Ralph, Steven D. Karlen
Format: Article
Language:English
Published: Nature Portfolio 2025-06-01
Series:Nature Communications
Online Access:https://doi.org/10.1038/s41467-025-60270-x
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author Canan Sener
Vitaliy I. Timokhin
Jan Hellinger
John Ralph
Steven D. Karlen
author_facet Canan Sener
Vitaliy I. Timokhin
Jan Hellinger
John Ralph
Steven D. Karlen
author_sort Canan Sener
collection DOAJ
description Abstract Hydrogenolysis of lignin generates a portfolio of products, the yields of which are generally calculated using a subset of phenolic monomers that are dependent on the lignin composition, product distribution, and analytical technique. Some lignins are naturally γ-acylated; poplar lignins, for example, have p-hydroxybenzoate groups on 1–15% of their syringyl subunits. Upon hydrogenolysis, it is generally assumed that the p-hydroxybenzoate is cleaved before the deacylated lignin is depolymerized. Hydrogenolysis of model γ-p-hydroxybenzoylated β-aryl ethers do not, however, produce the deacylated β-aryl ether intermediates, as was previously conjectured; products instead derive from palladium-assisted reactions on the cinnamyl p-hydroxybenzoates resulting in initial β-ether cleavage. The p-hydroxybenzoate moiety itself also undergoes carboxylate-assisted palladium-catalyzed C–H bond activation to form the 2,4-dihydroxybenzoate, that subsequently converts to the 2,4-dihydroxycyclohex-1-enoate. These details underscore previously unrecognized pathways and products that are key to understanding the different hydrogenolysis product distributions from naturally acylated lignins that are prevalent biomass-conversion feedstocks.
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issn 2041-1723
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publishDate 2025-06-01
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spelling doaj-art-24999a3ef6a945a083bf8824c8eafa2d2025-08-20T03:25:19ZengNature PortfolioNature Communications2041-17232025-06-011611810.1038/s41467-025-60270-xPd/C promotes C–H bond activation and oxidation of p-hydroxybenzoate during hydrogenolysis of poplarCanan Sener0Vitaliy I. Timokhin1Jan Hellinger2John Ralph3Steven D. Karlen4Wisconsin Energy Institute, University of WisconsinWisconsin Energy Institute, University of WisconsinWisconsin Energy Institute, University of WisconsinWisconsin Energy Institute, University of WisconsinWisconsin Energy Institute, University of WisconsinAbstract Hydrogenolysis of lignin generates a portfolio of products, the yields of which are generally calculated using a subset of phenolic monomers that are dependent on the lignin composition, product distribution, and analytical technique. Some lignins are naturally γ-acylated; poplar lignins, for example, have p-hydroxybenzoate groups on 1–15% of their syringyl subunits. Upon hydrogenolysis, it is generally assumed that the p-hydroxybenzoate is cleaved before the deacylated lignin is depolymerized. Hydrogenolysis of model γ-p-hydroxybenzoylated β-aryl ethers do not, however, produce the deacylated β-aryl ether intermediates, as was previously conjectured; products instead derive from palladium-assisted reactions on the cinnamyl p-hydroxybenzoates resulting in initial β-ether cleavage. The p-hydroxybenzoate moiety itself also undergoes carboxylate-assisted palladium-catalyzed C–H bond activation to form the 2,4-dihydroxybenzoate, that subsequently converts to the 2,4-dihydroxycyclohex-1-enoate. These details underscore previously unrecognized pathways and products that are key to understanding the different hydrogenolysis product distributions from naturally acylated lignins that are prevalent biomass-conversion feedstocks.https://doi.org/10.1038/s41467-025-60270-x
spellingShingle Canan Sener
Vitaliy I. Timokhin
Jan Hellinger
John Ralph
Steven D. Karlen
Pd/C promotes C–H bond activation and oxidation of p-hydroxybenzoate during hydrogenolysis of poplar
Nature Communications
title Pd/C promotes C–H bond activation and oxidation of p-hydroxybenzoate during hydrogenolysis of poplar
title_full Pd/C promotes C–H bond activation and oxidation of p-hydroxybenzoate during hydrogenolysis of poplar
title_fullStr Pd/C promotes C–H bond activation and oxidation of p-hydroxybenzoate during hydrogenolysis of poplar
title_full_unstemmed Pd/C promotes C–H bond activation and oxidation of p-hydroxybenzoate during hydrogenolysis of poplar
title_short Pd/C promotes C–H bond activation and oxidation of p-hydroxybenzoate during hydrogenolysis of poplar
title_sort pd c promotes c h bond activation and oxidation of p hydroxybenzoate during hydrogenolysis of poplar
url https://doi.org/10.1038/s41467-025-60270-x
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