Mechanistic Investigations of the Hydrogenolysis of Diaryl Ethers Catalyzed by Nickel Complexes of N-Heterocyclic Carbene Ligands.

ABSTRACT: Recent interest in the valorization of lignin has led to reactions involving the cleavage of strong aromatic C-O bonds. However, few experimental mechanistic studies of these reactions have been published. We report detailed mechanistic analysis of the hydrogenolysis of diaryl ethers catalyzed by the combination of Ni(COD)₂ (COD = 1,5-cyclooctadiene) and an N-heterocyclic carbene (NHC). Experiments on the catalytic reaction indicated that NaOt-Bu was necessary for catalysis, but kinetic analysis showed that the base is not involved in the rate-limiting C-O bond cleavage. The resting state of the catalyst is an NHC-Ni(η⁶-arene) complex. Substitution of the coordinated solvent with diaryl ether allowed isolation of a diaryl ether-bound Ni complex. Rate-limiting C-O bond

SUBMITTER: Saper NI 

PROVIDER: S-EPMC11620758 | biostudies-literature | 2017 Dec

REPOSITORIES: biostudies-literature