DFRC method for lignin analysys.: 1.: New method for βaryl ether cleavage:: Lignin model studies

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" was coined for derivatization followed by reductive cleavage. Derivatization, accompanied by cell wall solubilization, is accomplished with acetyl bromide (AcBr); reductive cleavage of resulting beta-bromo ethers utilizes zinc in acetic acid. Degradation monomers, 4-acetoxycinnamyl acetates, from beta-ether cleavage by the DFRC method were identified by NMR, CC-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 (> 92%) yield. The DFRC method produces simpler mixtures of monomers with higher yields than alternative hydrolytic methods. Because of its relative simplicity, mild conditions, and exceptional selectivity, this method should become a powerful analytical method for lignin characterization.