Ru-Catalyzed Hydrogenolysis of Lignin: Base-Dependent Tunability of Monomeric Phenols and Mechanistic Study

By Helong Li, Guo-yong Song. ACS Catalysis, 2019

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Substantial attention has been given to depolymerization of lignin into monomeric phenols in recent years because lignin is a renewable and CO2-netural aromatic resource. Recent results indicated that the base can shift the selectivity from C3-fragmented phenols to C2-fragmented phenols partially in transition metal-catalyzed lignin hydogenolysis, while reaction mechanisms have remained elusive. Using a series of dimeric, trimeric, and polymeric β-O-4 lignin mimics, as well as their deuterated analogues, we now report an in-depth experimental study on the mechanism of Ru/C-catalyzed hydogenolysis lignin. Experimental evidence based on substrate probes, reactivity examination of possible intermediates, and isotopic labeling experiments confirmed that the reported pathways, such as enol ether generated via α,β-dehydration reaction or Cα carbonyl compounds generated via dehydrogenation or consecutive Cβ–O and Cγ–OH bonds hydrogenolysis, are irrelevant to current reactions. For C3-fragmented phenols with Ru/C...

Subfields: Biomedical Engineering, Biotechnology, Plant Science

View Paper: https://www.semanticscholar.org/paper/b3b00617743e095ca265c8a1fea551604bbb7953