A DFT Mechanistic Study on Base-Catalyzed Cleavage of the β-O-4 Ether Linkage in Lignin: Implications for Selective Lignin Depolymerization.

ABSTRACT: The detailed mechanism of the base-catalyzed C-C and C-O bond cleavage of a model compound representing the β-O-4 linkage in lignin is elucidated using DFT calculations at the M06/6-31G* level of theory. Two types of this linkage have been studied, a C2 type which contains no γ-carbinol group and a C3 type which contains a γ-carbinol. Cleavage of the C2 substrate is seen to proceed via a 6-membered transition structure involving the cation of the base, the hydroxide ion and the α-carbon adjacent to the ether bond. The reaction with KOH has the lowest activation barrier of 6.1 kcal mol^-1 with a calculated rate constant of 2.1 × 10⁸ s^-1. Cleavage of the C3 substrate is found to proceed via two pathways: an enol-formation pat

SUBMITTER: Mensah M 

PROVIDER: S-EPMC8892242 | biostudies-literature | 2022

REPOSITORIES: biostudies-literature