Abstract
Here, we report a catalytic, light-driven method for the redox-neutral depolymerization of native lignin biomass at ambient temperature. This transformation proceeds via a proton-coupled electron-Transfer (PCET) activation of an alcohol O-H bond to generate a key alkoxy radical intermediate, which then facilitates the β-scission of a vicinal C-C bond. Notably, this single-step depolymerization is driven solely by visible-light irradiation, requires no stoichiometric chemical reagents, and produces no stoichiometric waste. This method exhibits good efficiency and excellent selectivity for the activation and fragmentation of the β-O-4 linkage in the polymer backbone, even in the presence of numerous other PCET-Active functional groups. The feasibility of this protocol in enabling the cleavage of the β-1 linkage in model lignin dimers was also demonstrated. These results provide further evidence that visible-light photocatalysis can serve as a viable method for the direct conversion of lignin biomass into valuable arene feedstocks.
Original language | English (US) |
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Pages (from-to) | 800-805 |
Number of pages | 6 |
Journal | ACS Catalysis |
Volume | 10 |
Issue number | 1 |
DOIs | |
State | Published - Jan 3 2020 |
All Science Journal Classification (ASJC) codes
- Catalysis
- General Chemistry
Keywords
- C-C bond cleavage
- alkoxy radicals
- lignin depolymerization
- photoredox catalysis
- proton-coupled electron transfer