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Mild heterogeneous palladium-catalyzed cleavage of β-o-4'-ether linkages of lignin model compounds and native lignin in air

Galkin, M. V., Sawadjoon, S., Rohde, V., Dawange, M. & Samec, J. S. M., 1-Jan-2014, In : ChemCatChem. 6, 1, p. 179-184 6 p.

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  • Mild Heterogeneous Palladium-Catalyzed Cleavage

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DOI

  • Maxim V. Galkin
  • Supaporn Sawadjoon
  • Volker Rohde
  • Monali Dawange
  • Joseph S.M. Samec

A mild and robust heterogeneous palladium-catalyzed C - O 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.

Original languageEnglish
Pages (from-to)179-184
Number of pages6
JournalChemCatChem
Volume6
Issue number1
Publication statusPublished - 1-Jan-2014
Externally publishedYes

    Keywords

  • cleavage reactions, green chemistry, heterogeneous catalysis, lignin, palladium, polymers

ID: 74457903