Issue 6, 2023

Mild and selective etherification of wheat straw lignin and lignin model alcohols by moisture-tolerant zirconium catalysis

Abstract

The direct etherification of wheat straw lignin and lignin model compounds using alcohols as reagents and zirconocene triflate as moisture-tolerant Lewis acidic catalyst is herein described. Visual kinetic analysis was used to assess the average orders in the reaction components to map similarities between the model substrates and guide the method development. Full selectivity for the formation of benzylic ethers was obtained for models bearing free phenols and/or aliphatic alcohols, demonstrating that the present strategy enables a complementary reactivity to traditional phenolic lignin functionalisation. The reaction proceeds under mild conditions in absence of water-scavenging techniques and furnished a variety of ethers derived from lignin models with side chains bearing synthetic handles of relevance for thermoset applications. Finally, application of the Zr-mediated protocol on wheat straw-derived lignin resulted in the first example of metal-catalysed direct benzylic allylation of lignin using allyl alcohol as reagent, generating water as by-product.

Graphical abstract: Mild and selective etherification of wheat straw lignin and lignin model alcohols by moisture-tolerant zirconium catalysis

Supplementary files

Article information

Article type
Paper
Submitted
06 Dec 2022
Accepted
01 Mar 2023
First published
02 Mar 2023
This article is Open Access
Creative Commons BY license

Green Chem., 2023,25, 2401-2408

Mild and selective etherification of wheat straw lignin and lignin model alcohols by moisture-tolerant zirconium catalysis

C. Margarita, D. Di Francesco, H. Tuñon, I. Kumaniaev, C. J. Rada and H. Lundberg, Green Chem., 2023, 25, 2401 DOI: 10.1039/D2GC04650D

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