Structure lignin

Hammel KE, MD Mozuch, KA Jensen, PJ Kersten (1994) HjOj recycling during oxidation of the arylglycerol P-aryl ether lignin structure by lignin peroxidase and glyoxal oxidase. Biochemistry 33 13349-13354. 

Zhang, L. Gellerstedt, G. NMR observation of a new lignin structure, a spiro-dienone. J. Chem. Soc., Chem. Commun. 2001, 2744—2745. 

Lapierre, C. Pollet, B. MacKay, J. J. Sederoff, R. R. Lignin structure in a mutant pine deficient in cinnamyl alcohol dehydrogenase. J. Agric. Food Chem. 2000, 48, 2326-2331. 

The oxidized mediator form, produced in the course of the enzymatic reaction, can nonenzymatically oxidize compounds (including nonphenolic lignin structures) with ionization potentials exceeding the potentials of laccases (Morozova and others 2007). 

Gould, R. F., ed., Lignin Structure and Reactions, Advances in Chemistry Series, American Chemical Society Publications, 1966. 

Gould, R. F., ed., Lignin Structure and Reactions, Advances in Chemistry Series, No. 59, American Chemical Society, Washington, D.C., 1966 and Rebello, A., "Composition of Wood", in Environmental Biogeochemistry, Nriagu, J., 2 vol., 1975, Ann Arbor Science Publishers, Ann Arbor, Michigan. 

Figure 6.5 Lignin structures identified in extracts from the white water from a newsprint machine.

The Norwegian company Borregaard makes vanillin by chemo-oxidation of cheap natural lignin. In view of the complexity of the lignin structure this is a remarkable achievement. This semi-synthetic vanillin is, however, not allowed to carry the qualification of natural . Borregaard is the only global producer of lignin-vanillin or wood-sourced vanillin , with a volume of about 2000 t a-1. They obtain 4 kg vanillin from one ton of wood. This vanillin is more expensive than synthetic vanillin, but the flavorist needs lower doses of the extra round flavor . 

The presence of lignin structural units was confirmed by retention time data and by comparisons of mass spectra to library spectra, to spectra of authentic standards, and to published mass spectra of lignin phenols Fill. 

The analysis of lignitic woods by analytical pyrolysis has shown that lignin structural units can be preserved as biomaikers in samples as old as Carboniferous age, or approximately 300 million years. At least half or more of the pyrolysis products in lignitic wood of Cretaceous age are methoxyphenols characteristic of lignin. The pn uct distributions in these Cretaceous samples indicate that the lignin is mainly altered in the 3-carbon side chains. Phenols, cresols, catechols, and other methylated phenols account for most of the remaining pyrolysis products. It is likely diat these products are also derived frx>m li in, especially lignin that has been altered by coalification reactions. 

Lignin Structure in situ in Vascular Plant CeU Walls... 

It should now be self-evident that substantial progress has been made in developing methodology to probe lignin structure in situ. Obviously similar strategies for suberin also could be developed. The following points can now be made ... 

Twenty-three years have elapsed since the American Chemical Society published a book devoted to papers from a symposium exclusively about lignin. In the preface to Lignin Structure and Reactions (Advances in Chemistry Series 59, 1966), the symposium chairperson remarked that the current presentation of lignin structure is oversimplified.. . . more ingenious work is needed to establish the sequence of units—the most prominent singular task of future lignin research. Presumably, the author of these words had in mind the sequence of intermonomer linkages rather than the units themselves (which differ only in their aromatic methoxyl substitution pattern), and from this perspective his observation could be as true in 1989 as it was in 1966. 

We should note, also, that the lignin in the S2 layers is chemically bonded to the polysaccharide moiety (87-92). Such bonds occur not only in wood but may be formed during chemical pulping (93,94). Even if the lignin-carbohydrate bonds are restricted to the hemicelluloses (95), the regularity of these chain molecules will probably impose some non-randomness on the lignin structure. 

Association of kraft lignin is mainly based on internal and external factors. The composition and the functional groups within the kraft lignin structure are important internal factors in determining the thermodynamic behavior of kraft lignin. The major groups are the aromatic ring (1/C9),... 

A considerable amount of data has accumulated regarding the modification of lignins to engineering plastics. Unfortunately, the incorporation of various monomers and polymers, such as di- and polyvalent epoxyphenols, esters and isocyanates, in the lignin structure in most cases resulted in brittle or tarry materials whose properties designated them as potential adhesives, lacquers, dispersants and films, but not as structural materials (36-40). 

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