Ethers, lignin

Hammel KE, MD Mozuch, KA Jensen, PJ Kersten (1994) HjOj recycling during oxidation of the arylglycerol P-aryl ether lignin structure by lignin peroxidase and glyoxal oxidase. Biochemistry 33 13349-13354. 

Schmidt, J.A., Berinstain, A.B., de Rege, F., Heitner, C., Johnston, L.J., Scaiano, J.C. "Effect of Solvent on the Photodegradation of a-Guaiacoxyacetoveratrone, A Phenacyl-a-Aryl Ether Lignin Model" In Paper Lignocellulosics, Science, Technology, Development and Use Kennedy, J.F., Philips,G.O. and Williams, P.A. eds , Ellis Harwood Limited, N. Y., p.587. 

Ralph, J. (1993) H NMR of acetylated P-ether/P-ether lignin model trimers. Magn. Reson. Chem. 31(4), 357-363. 

U Tuor, H Wariishi, HE Schoemaker, MH Gold. Oxidation of phenolic arylglycerol beta-aryl ether lignin model compounds hy manganaese peroxidase from Phanerochaete chrysosporium. Oxidative cleavage of an alpha-carhonyl model compound. Biochemistry 31 4986 995, 1992. 

Scheme 16.14 shows the reactions of two dimeric cyclic ether lignin models with O2 [64] Oxidation of the dimeric cyclic ether pinoresinol, 54 with O2 from NaOCl/ H2O2 at pH 7 underwent cleavage of the phenyl-aliphatic bond to produce meth-oxy-hydroquinone, 50 and 2,6-dihydroxy-3,7-dioxabicyclo [3.3.0] octane, 55. When treated under the same conditions as pinoresinol, 54, dihydrodehydrodiisoeugenol, 56 did not undergo any bond cleavage but rather an oxidation of the phenolic moiety to form the quinol, 57 (Scheme 16.14). 

JA Schmidt, AB Berinstain F de Rege, C Heitner, and LJ Johnston, Effect of Solvent on the Photodegradation of a-Guaiacoxylacetoveratrone, a Phenacyl- 3-aryl Ether Lignin Model, in JF Keimedy, GO Phillips, and PA Williams, Eds. Ligno-Cellidosics, Science, Technology, Development and Use. Chichester ElUs Horwood, 1992, p. 587. 

Proper extraction process needs special requirements to fractionate a certain hemicellulose or mixture of hemicelluloses. However, the presence of lignin network as well as ester and ether lignin-carbohydrate linkages limits the hemicellulose extraction... 

The MWEL is a very representative preparation to study ether lignin-carbohydrate linkages in wood since it would appear that it contains all of the original ether linkages [20]. Therefore, it is very appropriate to study the ether LCC linkages with the help of wet chemistry methods, such as meth-ylation and DDQ degradative techniques. However, in contrast to the CEL, the MWEL is not completely soluble in NMR solvents, and therefore its analysis by high-resolution spectroscopic methods is not viable. 

Fig. 3. Simide rquesentative hemicelluloses-ester-FA-ether-lignin tmdges.

Fig. 4. A simple leptesentative hemicelluloses-ester-diFA-ether-lignin bridge.

FIGURE 9.4 MnP-catalyzed oxidation of phenolic aryglycerol P-aryl ether lignin model compound (Wong, 2009). 

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