Thomas Q. Hu, Graham R. Cairns, Brian R. James
Removal of Phenolic Hydroxyl Groups in Lignin Model Compounds and Its Effect on Photostability
Summary
The phenolic hydroxyl groups in the lignin model compounds, 2-methoxy-4-propylphenol and 4-hydroxy-3-methoxyacetophenone, were removed by first converting the hydroxyl groups to the trifluoromethanesulfonates
(triflates) and then cleaving the triflate substituents via catalytic hydrogen transfer.
The products, 1-methoxy-3-propylbenzene and 3-methoxyacetophenone, were characterized by 1H and
13C NMR, mass spectrometry and elemental analyses. The effect of the removal of the phenolic groups
on the photostability of the model compounds was evaluated by impregnating the compounds into Whatman
filter paper sheets, and subjecting them to an accelerated yellowing experiment in a UV chamber.
The removal of the phenolic groups resulted in a significant yellowing inhibition, with a higher photostabilizing
effect than methylation or acetylation of the hydroxyl, particularly for the model compound
without an ?-carbonyl group.
Holzforschung, Walter de Gruyter
Print ISSN: 0018-3830
Volume: 54, 02/2000
Pages: 127 - 132
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