MEASUREMENT OF INDUCTION PERIODS IN INHIBITED FREE‐RADICAL OXIDATION BY INFRARED CHEMILUMINESCENCE AT 1270 nm

— Infrared chemiluminescence at 1.27 µ. appears after the consumption of phenolic inhibitors in solutions of 1-tetralyl hydroperoxide in tert-butylbenzene (BPh), initiated with di-tert-butyl hyponitrite (BHN) at 68oC. The induction periods with phenols were in excellent agreement with ones calculated from rates of decomposition of the initiator. Di-(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, benzhyd-rol, a derivative of benzhydrol, and di-rerr-butyl ketoxime under these conditions showed no inhibition or a weak effect. Initiated solutions 2.5 mM in p,p′-di-tert-octyldiphenylamine showed no detectable emission at 1270 nm because of efficient quenching of 1O2 by diaryl nitroxides formed from the amine, and because the oxidation products of the amine are peroxy scavengers (Thomas, J. R. 1960, J. Amer. Chem. Soc. 82, 5955). The relative yields of IR luminescence from several alkyl hydroperoxides and oxygen-hydrocarbon mixtures, initiated in each case by BHN, were found to vary substantially with the structure of the hydrocarbon and with the solvent.