Molecular Size Distribution of Lignin in Wood

Brown, Wyn; Falkehag, S. I.; Cowling, E.

doi:10.1038/214410a0

Cited by 44 publications

(22 citation statements)

References 2 publications

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“…Yet many authors have reported bimodal distributions of molecular weight in soluble lignins. Such bimodal behavior turns up not only in organosolv lignins (27)(28)(29) but also in lignins made soluble in the chemical pulping of wood (12,30 are being resolved into distributions with several maxima (31)(32)(33)(34)(35)(36)(37)(38). Some of these components are well-defined low molecular weight oligomers of the lignin macromolecule.…”

Section: Molecularmentioning

confidence: 99%

The Lignin Paradigm

Goring

1989

ACS Symposium Series

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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 delignified, the properties of the macromolecules made soluble reflect the properties of the network from which they are derived.

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Section: Molecularmentioning

confidence: 99%

The Lignin Paradigm

Goring

1989

ACS Symposium Series

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“…In lignin there are known to be few of the aldehydic and p-hydroxybenzyl alcohol groups. There would be numerous unsaturated alcohol groups at the boundary of the macromolecule, lignin being a finite polymer (Brown, Cowling and Falkehag 1968 a\s in the lignin formula of Freudenberg 1968). However, the most numerous reactive groups in lignin woulld be the free phenolic syringyl and guaiacyl groups, the<se woiuld be mainly responsible for the permanganate?…”

Section: Tissues Containing Polyphenolsmentioning

confidence: 99%

The Mechanism of Permanganate and Osmium Tetroxide Fixation and the Distribution of Lignin in the Cell Wall ofPinus radiata

Bland¹,

Foster²,

Logan³

1971

Holzforschung

121

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“…The individual blocks were brushed free of adhering mycelium, dried, and weighed and then collectively ground to pass a 40-mesh standard sieve. A separate group of blocks from the same lot (average weight loss 77.5%) was prepared similarly and analyzed as outlined by Brown et al 9 for Klason lignin, acid-soluble lignin, methoxyl content, and amounts of individual sugars after hydrolysis in sulfuric acid.…”

Section: Methodsmentioning

confidence: 99%

“…It is a substrate of particular interestg for comparison with milled wood lignin,lO~ll because it is apparently morphologically intact and nearly quantitatively representative of the lignin in wood. Other pertinent characteristics of enzymatically liberated lignins are discussed by Brown et al 9 The influence of chemical changes such as partial demethoxylation on the physical integrity of the polymer are unknown. I n an endeavor to obtain such information it was decided to make a comprehensive physicochemical and chemical comparison of this lignin with milled wood lignin and other lignin preparations from the same woods.…”

Section: Introductionmentioning

confidence: 98%

Preparative fractionation of lignin by gel‐permeation chromatography

1969

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SynopsisThe combination of an agarose gel (Bio-Gel A) and a dioxane-water (1:l) solvent system allowed the fractionation, on a preparative scale, of a very polydisperse, nonderivatized lignin preparation (enzymatically liberated lignin prepared from sweetgum sapwood with Lenzites trabea). Three fractions differing markedly in molecular weight were obtained. A gel of crosslinked alkylated dextran (Sephadex LH-20) with the same solvent system allowed division of the lowest molecular weight fraction into two fractions. These materials were characterized by measurements of intrinsic viscosity and number-average molecular weights in dimethylformamide and dioxane-water.It was established that the two highest molecular weight fractions were associated in an average trimeric form in dioxane-water (1 :1) as compared to the form (considered to be molecular) that occurred in dimethylformamide. Molecular size distributions and eluant volumes of the fractions were determined with a Sephadex G-1Wformamide system, the latter being one of the most powerful nonaqueous solvents for lignin. Adsorption effects were known to be absent in this case, and the lignin molecules were considered to be unassociated in formamide. The four fractions were distinguishable with the f0rmamide-G-100 system, thus indicating that the original fractionation was based on molecular size. The enzymatically liberated lignin contained molecules that comprised a continuum of molecular weights from approximately monomeric to molecules that were a t the limit of the solvating power of dioxane-water (1:l) and dimethylformamide. Limited physicochemical data were consistent with a compact, approximately spherically symmetric shape of the lignin in solution.

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Molecular Size Distribution of Lignin in Wood

Cited by 44 publications

References 2 publications

The Lignin Paradigm

The Lignin Paradigm

The Mechanism of Permanganate and Osmium Tetroxide Fixation and the Distribution of Lignin in the Cell Wall ofPinus radiata

Preparative fractionation of lignin by gel‐permeation chromatography

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