Monomeric lignin models

Kondo R, H Yamagami, K Sakai (1993) Xylosation of phenolic hydroxyl groups of the monomeric lignin model compounds 4-methylgnaiacol and vanillyl alcohol by Coriolus versicolor. Appl Environ Microbiol 59 438-441. 

Metabolism of Monomeric Lignin Models. Leisola and coworkers (31,37) have reported on the products of the lignin peroxidase catalyzed oxidation of veratryl alcohol. Veratraldehyde was the major product (> 70% yield), together with a number of minor products, the quinones 13 and 14 and the ringopened lactones 16 and 17. In addition, Shimada et al. (38,39) showed that the 6-lactone 18 was also formed. Recently we obtained evidence that the ortho-quinone 15 and the 6-lactone 19 were also products of the lignin peroxidase catalyzed oxidation of veratryl alcohol (Schmidt ef al, Biochemistry, in press). Mechanisms for the formation of those compounds... 

In an attempt to relate calculated results to experimental findings for monomeric, lignin model compounds, preliminary work has compared theoretically determined electron densities and chemical shifts reported from carbon-13 nuclear magnetic resonance spectroscopy (62). Although chemical shifts are a function of numerous factors, of which electron density is only one, both theoretical and empirical relationships of this nature have been explored for a variety of compound classes, and are reviewed by Ebra-heem and Webb (63), Martin et al. (64), Nelson and Williams (65), and Farnum (66). 

Monomeric lignin models Vanillin c8h8o, Eriksson and Gierer 1985... 

Elder, T. 1999. Correlation of experimental and ab initio C-NMR chemical shifts for monomeric lignin model compounds. J. Mol. Struct-Theochem. 505 257-267. 

K Tatsumi and N Terashima. Oxidative degradation of lignin. (4) Reactivities of monomeric lignin model compounds with hydrogen peroxide. Mokuzai Gakkaishi 27 873-878, 1981. 

HR Nimz and H Schwind. Oxidation of monomeric lignin model compounds with peracetic acid. Cellulose Chem. Technol. 13 35 6, 1979. 

Since all of the model compounds examined were monomeric lignin-like structures, our current studies do not address the possibility of an intramolecular photochemical initiated reaction contributing to brightness reversion. Investigations directed at examining this latter issue are ongoing. 

In this section, examples of information available from ozonation of lignin model compounds, related compounds, and lignins will be presented. Table 6.7.2 lists the monomeric and dimeric lignin model compounds that have been ozonated. 

In other work related to bleaching chemistry, the reactions of chlorine dioxide with monomeric [44] and dimeric [45] lignin model compounds have been studied computationally. These studies closely parallel experimental work in which oxidation mechanisms were proposed [46-51]. In accord with the experimental work, which reports higher reactivity of phenolic compounds, the heats of reaction for these compounds are lower than those for etherified models. The experimentally based mechanisms were generally found to be energetically feasible, but in some cases the electronic results were not consistent with the proposed mechanisms. 

Gierer, J. Opara, A. E. Enzymic degradation of lignin. Action of peroxidase and laccase on monomeric and dimeric model compounds. Acta Chem. Scand. 1973, 27,... 

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