Lignins in wood

Solution Properties. Lignin in wood behaves as an insoluble, three-dimensional network. Isolated lignins (milled wood, kraft, or organosolv lignins) exhibit maximum solubiUty in solvents having a Hildebrand s solubiUty parameter, 5, of 20.5 — 22.5(J/cm ) (10 — ll(cal/cm ) > and A// in excess of 0.14 micrometer where A]1 is the infrared shift in the O—D bond when the solvents are mixed with CH OD. Solvents meeting these requirements include dioxane, acetone, methyl ceUosolve, pyridine, and dimethyl sulfoxide. 

B. J. Fergus, "The Distribution of Lignin in Wood as Determined by Ultraviolet Microscopy," Ph.D. thesis, McGill University, Montreal, Canada,... 

The support for a chemical linkage between cellulose and lignin in wood, presented by Hibbert and co-workers (90), is based on their treatment of oak wood with acetic anhydride, glacial acetic acid and catalytic amounts of sulfuric acid. A fraction soluble in dioxane was found to have, after several precipitations, the same composition of lignin, cellulose and pentosan as that of the wood itself. 

Importantly, most of these degradative reactions of lignin sub-structiare models were also suggested to occur in the degradation of proto lignin in wood (6). 

Saka, S. Goring, D. A. I. Localization of Lignins in Wood Cell Walls In Biosynthesis and Biodegradation of Wood Components Higuchi, T., Ed. Academic Press New York, 1985 pp. 51-62. 

Evidence supporting the original paradigm of lignin in wood as a random, three-dimensional network polymer is reviewed. More recent results which do not fit this simple picture are discussed. A modified paradigm is proposed in which lignin in wood is comprised of several types of network which differ from each other both ultrastructurally and chemically. When wood is deligni-fied, the properties of the macromolecules made soluble reflect the properties of the network from which they are derived. 

On heating wood meal for 16 h with the dioxane-phosphate buffer, 17% of the total lignin in wood dissolved. As revealed by Figure 13, about... 

American Society for Testing and Materials. (1956), Standard Test for Lignin in Wood, D 271-248, American Society for Testing and Materials, Philadelphia, PA. 

Schuerch C (1952) The solvent properties of liquids and their relation to the solubility, swelling, isolation and fractionation of lignin J Am Chem Soc 74 5061-5067 Scott JAN, Procter AR, Fergus BJ, Goring DAI (1969) The application of ultraviolet microscopy to the distribution of lignin in wood Description and validity of the technique Wood Sci Technol 3 73 - 92... 

Determination of Acid-Insoluble (Klason) Lignin in Wood and Pulp... 

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