Copper Catalyzed Alcohol Oxidation and Cleavage of β-O-4 Lignin Model Systems: From Development to Mechanistic Examination

Lignin, an abundant natural polymer with high aromaticity, is a potential source of renewable chemicals and fuels among other biomaterials. Herein, a study on copper catalyzed alcohol oxidation and cleavage of lignin β-O-4 model substrates is reported. The potential of CuX/BiPy/TEMPO(/additive) systems (X=halide or triflate, BiPy=2,2’-bipyridine; TEMPO=2,2,6,6-tetramethylpiperidine-N-oxyl) was explored and the optimized protocol was studied with several type of model compounds. Mechanistic studies elucidated two types of cascade reactions: Both involve a cleavage of Cα–Cβ bond, which is most likely activated by 1) primary alcohol oxidation in β-O-4 glycerolaryl ethers resulting in retro-aldol cleavage and 2) Cβ–H oxidation after secondary alcohol oxidation in β-O-4 ethanolaryl ethers leading to oxidative radical cleavage. The first process affords aromatic aldehydes while the latter delivers aryl acids.

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biomass conversion, catalysis, copper, lignin, oxidation

DOI

10.1002/slct.201802715

Citation

Salonen, H E P, Mecke, C P A, Karjomaa, M I, Joensuu, P M & Koskinen, A M P 2018, ' Copper Catalyzed Alcohol Oxidation and Cleavage of β-O-4 Lignin Model Systems : From Development to Mechanistic Examination ', ChemistrySelect, vol. 3, no. 44, pp. 12446-12454 . https://doi.org/10.1002/slct.201802715

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https://urn.fi/URN:NBN:fi:aalto-201903112200

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[article-cris] Kemian tekniikan korkeakoulu / CHEM

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Copper Catalyzed Alcohol Oxidation and Cleavage of β-O-4 Lignin Model Systems: From Development to Mechanistic Examination

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