REACTIONS OF LIGNIN WITH CYANAMIDE ACTIVATED HYDROGEN-PEROXIDE PART 1- THE DEGRADATION OF LIGNIN MODEL COMPOUNDS

Monomeric lignin model compounds representing various functional group s found in residual lignins were reacted with cyanamide activated hydr ogen peroxide. Non-phenolic lignin model compounds failed to react eve n under extreme reaction conditions (90 degrees C), while phenolic lig nin model compounds underwent rapid oxidation. Reaction optimization s tudies reveal that these reactions are strongly dependent on pH and th e cyanamide-to-peroxide ratio, while temperature is not a factor. Thro ugh the use of electron paramagnetic resonance (EPR) spectroscopy free radical involvement has been demonstrated. Ln contrast to previous li terature, a predominately free-radical mechanism exists, and on the ba sis of the reactions carried out in the presence of superoxide dismuta se, the presence of . O-2(-) has been determined.