Lignins acetyl

Scientific NamelCommon Name Cellulose cellulose Lignin Acetyl extractives ... 

Functional Group Analysis. The total hydroxyl content of lignin is determined by acetylation with an acetic anhydride—pyridine reagent followed by saponification of the acetate, and followed by titration of the resulting acetic acid with a standard 0.05 W sodium hydroxide solution. Either the Kuhn-Roth (35) or the modified Bethge-Liadstrom (36) procedure may be used to determine the total hydroxyl content. The aUphatic hydroxyl content is determined by the difference between the total and phenoHc hydroxyl contents. 

Scientific name/Common name Glucan Xylan Galactan Arabinan Man nan Uronic anhydride Acetyl Lignin Ash... 

At3g06550 - are deficient in wall-bound acetate. It would be interesting to test their resistance, lignin depositions and other physiological parameters under the influence of pathogens. It may be that these experiments will make clear the role of polysaccharide acetylation. 

Repeated methylation of bagasse native lignin with dimethyl sulfate yielded a product with a 29-1 % methoxyl content. Four such methyl-ations did not change this value. However, the infrared spectrum of this derivative still revealed a small absorption band at 3400 cm1. Thus, it appeared that at least one hydroxyl group could not be methylated. Treatment of this methylated product with acetic anhydride and pyridine gave an acetate, which did not exhibit an absorption band at 3400 cm-1. Consequently, a tertiary hydroxyl group, which can be acetylated but not methylated, seems to be present in this lignin. 

The band at 280 mp persists in spite of such alterations in the molecule as are caused by inethylation, acetylation and treatment with sodium hydroxide. However, the absorption of the phenylhydrazones of spruce (33) and white Scots pine native lignins 111) are peculiar in that a second maximum occurs at 352 mp. Glading (33) suggests that the carbonyl group in spruce native lignin is highly enolized, and, therefore,... 

Callow, H.J. (1951). Acetylation of cellulose and lignin in jute. Journal of the Indian Chemical Society, 28(11), 605-610. 

Ohkoshi, M. and Kato, A. (1997b). C-NMR analysis of acetyl groups in acetylated wood II. Acetyl groups in lignin. Mokuzai Gakkaishi, 43(4), 364—369. 

Sander, C. and Koch, G. (2001). Effects of acetylation and hydrothermal treatment on lignin as revealed by cellular UV-spectroscopy in Norway spruce (Picea abies [L.] Karst.) Holzforschung, 55(2), 193-198. 

Even the mildest pulping process, hydrotropic extraction, i.e. repeated extraction with concentrated aqueous solutions of organo-philic electrolytes such as sodium xylenesulfonate or cymenesulfonate, has failed because of an outlet for the extracted lignin, wliich is precipitated by mere dilution of the solution. Other methods based on hydrolysis of the wood with acids, e.g. HCl, HNO3, AICI3, acetic acid, acetyl chloride, SOg, or phenol, are merely of laboratory interest. 

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