REACTION OF A STABLE NITROXYL RADICAL WITH METALLOPHENOLS

ESR has been used to investigate the kinetics of liquid-phase reaction s of 2,2,6,6-tetramethylpiperidin-1-oxyl with -hydroxybenzylidene)-4-h ydroxy-3,5-dimethylaniline (PhH) and its complexes with Co2+, Fe2+, an d Ni2+ (Ph2Co, Ph2Fe, and Ph2Ni). It has been established that the rea ction proceeds bimolecularly. The following rate constants have been d etermined (in liters/moles.sec): PhH 7.8.10(3) exp(-2918/T); Ph2Co 1.0 .10(4) exp(-2654/T); Ph2Fe 2.9.10(3) exp(-2249/T); Ph2Ni 1.3.10(3) exp (-2078/T). It has been concluded that the presence of the metal in th e chelate unit increases the reactivity of the phenol group to a sligh t degree.