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Issue 8, 2002
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Singlet oxygen mediated degradation of lignin—isolation of oxidation products from steam-exploded lignin from pine

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Abstract

Lignin obtained from steam explosion of pine was fully characterized. Elemental analysis, GPC, and ultraviolet and 1H and 13C NMR spectra revealed that the obtained lignin contains both guaiacyl and syringyl units. Lignin was dissolved in acetonitrileethanol and treated with visible light in the presence of both oxygen and Rose Bengal for different irradiation times. Column chromatography of the residue showed the presence of six compounds: trans-sinapyl alcohol, 4-hydroxy-3,5-dimethoxybenzaldehyde, 4-hydroxy-3,5-dimethoxyphenylacetone, 4-hydroxy-3-methoxybenzaldehyde, cis-sinapyl alcohol, and sinapyl aldehyde. The total amount of fine chemicals increases with the irradiation time. However, it increases rapidly during the first eight hours, but increases slowly after this period. The most important compounds obtained were sinapyl alcohol and 4-hydroxy-3,5-dimethoxybenzaldehyde, but sinapyl alcohol was obtained in the highest amounts after eight hours' irradiation, while the highest amounts of 4-hydroxy-3,5-dimethoxybenzaldehyde were obtained after irradiation for 4 h. After 48 h irradiation comparable amounts of sinapyl aldehyde were obtained. We obtained only compounds derived from the syringyl units in lignin in agreement with the hypothesis that the guaiacyl units are more easily oxidised.

Graphical abstract: Singlet oxygen mediated degradation of lignin—isolation of oxidation products from steam-exploded lignin from pine

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Article information


Submitted
04 Mar 2002
Accepted
24 May 2002
First published
24 Jun 2002

Photochem. Photobiol. Sci., 2002,1, 570-573
Article type
Paper

Singlet oxygen mediated degradation of lignin—isolation of oxidation products from steam-exploded lignin from pine

C. Bonini, M. D'Auria and R. Ferri, Photochem. Photobiol. Sci., 2002, 1, 570
DOI: 10.1039/B202209E

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