An EPR investigation into the reactions of alkaline hydrogen peroxide with cyanamide

Abstract

Free-radical involvement in an alkaline hydrogen peroxide/cyanamide system has been demonstrated using electron paramagnetic resonance (EPR) spectroscopy. A stable free radical is formed which shows coupling to two pairs of equivalent ¹⁴N nuclei (a_¹⁴N1 = 7.30, a_¹⁴N2 = 2.13 G). Both hydroxyl and carbon-centered radicals have been trapped with 5,5-dimethyl-4,5-dihydro-3H-pyrrole N-oxide (DMPO) (DMPO–OH: a_H = a_N = 14.9 G, DMPO–C: a_H = 24.0, a_N = 16.4 G). The presence of HOO˙ has been inferred based on the absence of reactivity in the presence of superoxide dismutase. Involvement of superoxide and cyanamide radicals has been demonstrated by the formation of ring-opened and cyanamide coupled products obtained from reactions of alkaline hydrogen peroxide–cyanamide with substituted aromatic compounds.