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Differences in biosyntheses of guaiacyl and syringyl lignins in woods (1977)

Higuchi, T. ; Shimada, M. ; Nakatsubo, F. ; [et al.]

Springer

Wood science and technology 11 (1977), S. 153-167

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ISSN: 1432-5225

Source: Springer Online Journal Archives 1860-2000

Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Notes: Summary Metabolic differences in the formation of guaiacyl and syringyl lignins were explained in terms of the different functions of O-methyltransferases and reducing enzymes which participate in methylation and reduction of the hydroxycinnamic acid intermediates in the biosynthetic pathway of these two types of lignins. Sinapyl alcohol was dehydrogenated with peroxidase and H2O2 under various reaction conditions. Chemical properties of the dehydrogenation polymers (DHPs) formed were characterized, and the possible occurrence of syringyl lignin in hardwood was discussed. DHP and dimers of p-coumaryl alcohol were also characterized and discussed in relation to the formation of grass lignin which contains p-hydroxyphenyl propane as an additional lignin monomer.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00350993

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13C nuclear magnetic resonance studies of cellulose acetate (1984)

Miyamoto, T. ; Sato, Y. ; Shibata, T. ; [et al.]

New York : Wiley-Blackwell

Journal of Polymer Science: Polymer Chemistry Edition 22 (1984), S. 2363-2370

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ISSN: 0360-6376

Keywords: Physics ; Polymer and Materials Science

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: 13C-NMR spectra of ring carbons and O-acetyl carbonyl carbons of cellulose acetate (CA) in dimethyl sulfoxide-d6 were analyzed. The CA samples with the degree of substitution (DS) ranging from 0.84 and 1.91 were prepared by homogeneous acetylation of cellulose with acetic anhydride in a 10% LiCl/dimethyl acetamide solvent. It was found that the use of these low DS samples permitted easier assignments not only of the ring carbon but also of the O-acetyl carbonyl carbon signals. The assignments were confirmed by comparing with the 1H-NMR spectra of the samples obtained by complete acetylation of the corresponding CA samples with acetyl-d3 chloride. Two methods for determining the distribution of O-acetyl groups of CA, i.e., the relative DS at the three different types of hydroxyl groups, were developed. One is based on the measurements of the relative intensities of the signals for the ring carbons and the other is based on the measurements of the relative intensities of the signals for the O-acetyl carbonyl carbons.

Additional Material: 4 Ill.