Monomeric lignin model compounds representing various functional groups found in residual lignins were reacted with cyanamide activated hydrogen peroxide. Non-phenolic lignin model compounds failed to react even under extreme reaction conditions (90 °C), while phenolic lignin model compounds underwent rapid oxidation. Reaction optimization studies reveal that these reactions are strongly dependent on pH and the cyanamide-to-peroxide ratio, while temperature is not a factor. Through the use of electron paramagnetic resonance (EPR) spectroscopy free radical involvement has been demonstrated. In contrast to previous literature, a predominately free-radical mechanism exists, and on the basis of the reactions carried out in the presence of Superoxide dismutase, the presence of ·Ο 2 -has been determined.

The reactions of monomeric phenolic lignin model compounds with cyanamide activated hydrogen peroxide were studied. Analyses of the various reaction products indicate four main reactions occur; aromatic hydroxylation, demethoxyiation, radical coupling and oxidative ring opening. The predominate products from apocynol and acetoguaiacohe were dicarboxylic acid compounds, maleic/fumaric, oxalic, and succinic acid derivatives, consistent with degradation by Superoxide. In the degradation of creosol, 3-hydroxy-4-methoxy-6-methyl-N-methylaniline was the major compound isolated, providing evidence of a cyanamide radical. Finally, plausible pathways to the formation of Superoxide anion and cyanamide oxidation products from alkaline hydrogen peroxide and cyanamide are proposed and their impact on delignification is discussed.