On the Determination of β-Aryl Ether Units in Wood Lignin by an Ozonation Method

Abstract

The determination of lignin structures by ozonation is rather unique and unlike other analytical techniques is based largely on the formation of side-chain oxidation products. Also, it can readily reveal the proportion of the two stereoisomers of β-aryl ether structures from the yields of erythronic (E) and threonic (T) acids. We have observed that the relative yields of these two acids vary significantly depending on how they are determined. For example, the E/T ratio of these two tetronic acids from the ozonation of spruce wood lignin in situ varies from 1.10 to 1.57 based on their analysis as the free acid and lactone derivatives, respectively. Thus, the work-up procedure of the reaction products is very important to the ozonation technique.

Keywords:

• Ozonation
• β-Aryl ether units
• Erythro/threo ratio
• Lignin analysis

Acknowledgments

The financial support of this study by the Empire State Paper Research Associates (ESPRA) and by the U.S. Department of Energy (Award NO. DE-FC07-96 ID-134438) is gratefully appreciated.