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Chemical modeling of lignin

Train, P.M. Stochastic and Chemical Modelling of Lignin Liquefaction. Ph.D. Thesis, University of Delaware, 1987. [Pg.262]

Shevchenko, S. M., T. J. Elder, S. G. Semenov, andM. Ya.Zarubin. 1995. Conformational effects on the electronic structure and chemical reactivity of lignin model p-quinone methides and benzyl cations. Res. Chem. Inter. 21(3-5) 413 23. [Pg.346]

It is widely accepted that lignin is not a constitutionally defined compound, but that it is a physically and chemically heterogeneous material consisting of representative phenylpropane structures shown in Scheme 1. The phenylpropane units conjugate variously in the biosynthesis process and form a three dimensional polymer which does not have an ordered and regular macromolecular structure. The structural models of lignins have been illustrated by many authors, for example [12-14]. [Pg.7]

Barakat A, Chabbeit B, Cathala B (2007) Effect of reaction media concentration on the solubility and the chemical structure of lignin model compounds. Phytochemistry 68 118-25... [Pg.55]

Ralph, J. Lignin model quinone methides—facts and fallacies. In Proceedings of the Third International Symposium of Wood and Pulping Chemistry, Vancouver, BC, Canada, Chemical Institute of Canada (CIC), and Canadian Pulp and Paper Association (CPPA), Canada. 1985. [Pg.417]

Thus, a small concentration of ortho- or parabenzoquinone species in an environment of phenolic functions could explain the radical enhancement upon basification. The residual spin content of the neutral or acid form of lignin is almost nil in whole wood, very small in native lignins, but significant in kraft and other chemically modified lignins. Such a stable free radical could be attributed to (a) the small equilibrium concentration of I in Equation 1, (b) a semiquinone polymer patterned after synthetic models (4y 25) containing donor and acceptor groups, or (c) radicals entrapped and stabilized in a polymeric matrix (5,15). [Pg.67]

Hoffer, A., Kiss, G., Blazso, M., and Gelencser, A. (2004). Chemical characterization of humic-like substances (HULIS) formed from a lignin-type precursor in model cloud water. Geophys. Res. Lett., 31, doi 10.1029/2003GL018962. [Pg.480]

Effect of Chemical Modification with Polyethylene Glycol on the Brightness Stability of Lignin Model Compounds and High-Yield Pulp... [Pg.205]

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Lignin models

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