The Reactions of Lignin with Alkaline Hydrogen Peroxide. Part V. The Formation of Stilbenes.

Abstract

The reaction of 3-ethoxy-2,3-bis(4-hydroxy-3-methoxyphenyl)propanol (I) [54443-58-2] as a lignin [9005-53-2] model compd. with H2O2 at pH 12 and 14 resulted in the formation of 2,3-bis(4-hydroxy-3-methoxyphenyl)-2-propen-1-ol (II) [54208-45-6] and of II with 4,4'-dihydroxy-3,3'-dimethoxystilbene (III) [4957-27-1], resp., indicating that during the H2O2 bleaching of pulp, structures are introduced into lignin that can be easily converted into quinones (III is a vinylog of hydroquinone). The reaction of I with H2O2 at 30.degree. and pH 12-14 followed the 1st order kinetics.