ON THE PRODUCTION OF NITROXIDE RADICALS BY SINGLET OXYGEN REACTION: AN EPR STUDY

Abstract— The production of free radicals by reaction of 2,2,6,6-tetramethyl-4-piperidinol with singlet oxygen was studied by EPR spectroscopy. The rate constant of the amine was found to be equal to 8 ×10⁵ M ^-1s^-1 in ethanol and to 4 × 10⁷M^-1s^-1 in phosphate buffer (pH 8). Competition experiments were performed with singlet oxygen quenchers such as NaN₃, DABCO and the quenching rate constants were found to be consistent with the literature values. The EPR method proved to be a valuable technique to study the reaction of singlet O₂ with the sterically hindered amine without any interfering effect.