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United States Department of Agriculture

Agricultural Research Service

Title: The Dfrc Method for Lignin Analysis. Part 1. a New Method for Beta-Aryl Ether Cleavage: Lignin Model Studies

Authors
item Lu, Fachuang - UNIV OF WISCONSIN-MADISON
item Ralph, John

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 3, 1997
Publication Date: N/A

Interpretive Summary: Lignin, a major component in all plants, is a polymer that limits digestion of plants by animals and is what must be removed from wood to make paper. There are many analytical methods for lignin but no chemical method is as valuable as a technique called thioacidolysis, developed in France. However thioacidolysis uses extraordinarily noxious and stinky chemicals that make the method difficult to carry out even in a modern lab environment. We hav developed a method that gives the same type of analytical data as thioacidolysis but is much less noxious. Furthermore, the conditions and the chemistry are much simpler and more selective and give higher yields of the products that are analyzed. The new method has been coined the "DFRC" method (for Derivatization Followed by Reductive Cleavage, but also identifying the Dairy Forage Research Center where it was developed). The DFRC method cleanly degrades lignins (even in whole plant materials) to simple analyzable compounds that give a tremendous insight into the structural details of the original lignin. Scientists will use this technique in a wide variety of studies ranging from optimization of pulping processes in pulp mills to the identification of how a plant responds to various genetic mutations that are forced on it. Such studies are at the heart of efforts to improve agricultural sustainability.

Technical Abstract: A new method for selective and efficient cleavage of arylglycerol-beta-aryl (beta-O-4) ether linkages in lignins is described and applied to several lignin beta-ether models. The term "DFRC" for was coined Derivatization Followed by Reductive Cleavage. Derivatization, accompanied by cell wall solubilization, is accomplished with acetyl bromide (AcBr); reductive cleavage of resulting beta-bromoethers utilizes zinc in acetic acid. Degradation monomers, 4-acetoxycinnamyl acetates, from beta-ether cleavage by the DFRC method were identified by NMR, GC-MS and comparison of GC retention times with authentic compounds. Under the conditions used in this study, the beta-ether linkage of all models was cleaved in very high yield. Compared to hydrolytic methods (acidolysis, thioacidolysis), the DFRC method produces the simplest mixtures of monomers with higher yields. Because of its relative simplicity, mild conditions, and exceptional selectivity, this method should become a powerful analytical method for lignin characterization.

Last Modified: 12/20/2014
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