REACTIONS OF LIGNIN WITH CYANAMIDE ACTIVATED HYDROGEN-PEROXIDE PART 2- THE DEGRADATION MECHANISM OF PHENOLIC LIGNIN MODEL COMPOUNDS

The reactions of monomeric phenolic lignin model compounds with cyanam ide activated hydrogen peroxide were studied. Analyses of the various reaction products indicate four main reactions occur; aromatic hydroxy lation, demethoxylation, radical coupling and oxidative ring opening. The predominate products from apocynol and acetoguaiacone were dicarbo xylic acid compounds, maleic/fumaric, oxalic, and succinic acid deriva tives, consistent with degradation by superoxide. In the degradation o f creosol, 3-hydroxy-4-methoxy-6-methyl-N-methylaniline was the major compound is elated, providing evidence of a cyanamide radical. Finally , plausible pathways to the formation of superoxide anion and cyanamid e oxidation products from alkaline hydrogen peroxide and cyanamide are proposed and their impact on delignification is discussed.