Wood lignin

The polydispersity of softwood milled wood lignin, as measured by M /M = 2.5, is high compared with that of cellulose and its derivatives. 

Fig. 12. Portion of dynamic thermogravimetric curves between 130 and 400°C, with temperature rising 6°C per minute for wood, lignin, and a-ceUulose.

The structure of the second abundant component of the wood, lignin (Fig. 12) has been extensively studied using liquid state NMR and very detailed information... 

Karhunen, P Rummakko, P. Pajunen, A. Brunow, G. Synthesis and crystal structure determination of model compounds for the dibenzodioxocine structure occurring in wood lignins. J. Chem. Soc., Perkin Trans. 1996, 1, 2303-2308. 

Milled wood lignin (MWL) is produced by grinding wood in a rotary or vibratory ball mill. Lignin can be extracted from the resulting powder using solvents such as methylbenzene or... 

Lignin from Sound Wood Lignin from Decayed Wood... 

We considered whether to measure whole wood, lignin, or cellulose, wood being about 25 percent lignin on the average [18]. 

Sudo, K., Shimizu, K. and Sakurai, K. (1985). Characterization of steamed wood lignin from beech wood. Holzforschung, 39(5), 281-288. 

Comparisons made between unpurified spruce milled-wood lignin fractions and unfractionated poljrmers made from coniferjd alcohol alone already revealed the great qualitative similarity between natural and biosynthetically duplicated lignins [see, for example, K. Freudenberg in 94), pp, 125—126]. When a purified lignin fraction is compared tvith an identical fraction made from a mixture of all three -coumaryl alcohols, the resemblance is of course much greater. 

Kawamura, /., and T, Higuchi Comparative Studies of Milled Wood Lignins from Different Taxonomical Origins by Infrared Spectroscopy. In (10), pp.439--f56. 

Okay, A. Hydrogenation Products of Spruce Milled-Wood Lignin and of Related Model Compounds. Holzforschung J7, 105—110 (1963) J. Org. Chem. 27, 1783-1786 (1962). 

Sarkanen, K. V. Wood Lignins. In Browning, B. L. (Editor) The Chemistry of Wood. Interscience Publishers, New York-London, 1963, pp. 249-311. 

Konishi et al. (4,5) reported that milled wood lignin (MWL) treated with the laccase from C. versicolor suffered oxidative polymerization, depolymerization producing... 

Figure 1. Among the five resonance structures shown, Ra, Rb and Rc will undergo random coupling reactions more readily than Rd and Re, since the radicals Rd and Re are sterically hindered. Indeed, this is what is found experimentally, since only minor amounts of 0-1 structures (derived from Rd) have been found in milled wood lignin (22,23), and demethoxylation does not occur to any appreciable extent during lignin formation (21). The reactivity of the phenoxy radical, Ra, will be affected greatly by pH since it can be masked by protons under acidic conditions, and its reactivity will thus be diminished. On the other hand, the reactivity of Rb and Rc will not be affected appreciably by pH. Thus more frequent coupling of Rb-Rc, Rb-Rb and Rc-Rc can be expected at low pH, and more of Ra-Rb and Ra-Rc coupling at high pH.

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