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Study of alcoholic extraction of lignin by infrared spectrophotometry

J. Polčin, B. Košíková, J. Suchý, and M. Vašátková

Slovak Academy of Sciences, Bratislava

 

Abstract: By studying the kinetics of the methanolysis of milled spruce (Picea excelsa) and poplar (Populus monilifera) woods by infrared spectrophotometry, it was detd. that the absorption band at 1510 cm-1, corresponding to the aromatic ring, decreased in the extd. wood and at the same time there was a corresponding increase of absorption in MeOH exts. The extinction of the residual lignin in the wood was practically the same as that of an equal amt. of lignin which passed into the MeOH soln. The dependence of the extinction on lignin concn. conformed to Beer's law. The extinction of the residual lignin in wood, exposed to the action of an HCl soln. in MeOH at boiling temps. for a relatively short time, was twice as high in spruce and 60% higher in poplar than the extinction of an equal amt. of Klason lignin in the original wood. This increase of the absorption intensity can be explained by the cyclization of the propane chain with the formation of conjugated double bonds with the C5H6 ring, giving flavine or coumarone structures. The absorption intensity at 1230 cm-1 and 1270 cm-1, corresponding to the aromatic methoxyls, was related linearly to the amt. of Klason lignin in the wood.

Full paper in Portable Document Format: 167a562.pdf (in Slovak)

 

Chemical Papers 16 (7) 562–573 (1962)

Wednesday, October 23, 2019

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