Abstract
| - A new method for selective and efficient cleavage ofarylglycerol-β-aryl (β-O-4) ether linkages inlignins is described and applied to several lignin β-ether models.The term “DFRC” was coined forderivatization followed by reductive cleavage. Derivatization,accompanied by cell wall solubilization,is accomplished with acetyl bromide (AcBr); reductive cleavage ofresulting β-bromo ethers utilizeszinc in acetic acid. Degradation monomers, 4-acetoxycinnamylacetates, from β-ether cleavage bythe DFRC method were identified by NMR, GC−MS, and comparison of GCretention times withauthentic compounds. Under the conditions used in this study, theβ-ether linkage of all modelswas cleaved in very high (>92%) yield. The DFRC method producessimpler mixtures of monomerswith higher yields than alternative hydrolytic methods. Because ofits relative simplicity, mildconditions, and exceptional selectivity, this method should become apowerful analytical methodfor lignin characterization. Keywords: Acetyl bromide; lignin; lignin model compound; β-aryl ether;thioacidolysis; β-bromoether; cleavage; quantitative analysis; gas chromatography; reductiveelimination; acetylation;bromination
|