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- Title
Mild Heterogeneous Palladium-Catalyzed Cleavage of β- O-4′-Ether Linkages of Lignin Model Compounds and Native Lignin in Air.
- Authors
Galkin, Maxim V.; Sawadjoon, Supaporn; Rohde, Volker; Dawange, Monali; Samec, Joseph S. M.
- Abstract
A mild and robust heterogeneous palladium-catalyzed CO bond cleavage of 2-aryloxy-1-arylethanols using formic acid as reducing agent in air was developed. The cleaved products were isolated in 92-98 % yield; and by slightly varying the reaction conditions, a ketone, an alcohol, or an alkane can be generated in near-quantitative yield. This reaction is applicable to cleaving the β- O-4′-ether bond found in lignin polymers of different origin. The reaction was performed on a lignin polymer model to generate either the monomeric aryl ketone or alkane in a quantitative yield. Moderate depolymerization was achieved with native lignin at similar reaction conditions. Mechanistic studies under kinetic control indicate that an initial palladium-catalyzed dehydrogenation of the alcohol is followed by insertion of palladium to an enol equivalent. A palladium-formato complex reductively cleaves the palladium-enolate complex to generate the ketone.
- Subjects
PALLADIUM carbonyls; ETHERS; SPECTRUM analysis; LIGNINS; CARBON cycle; CHEMICAL bonds; KETONES
- Publication
ChemCatChem, 2014, Vol 6, Issue 1, p179
- ISSN
1867-3880
- Publication type
Article
- DOI
10.1002/cctc.201300540