Radical scaveging mechanism of distearyl hydroxylamine antioxidant

Abstract

Distearyl hydroxylamine has been developed as a polymer stabilizer, but the mechanism of action has not yet been clarified. The mechanism was investigated by evaluating the radical-scavenging potential. Distearyl hydroxylamine could better scavenge oxygen-centered radicals such as an alkoxy radical than carbon-centered radicals. The αα-dimethylbenzyloxy radical scavenging ability (kinh=5.8×104 dm 3.mol-1.s-1) of distearyl hydroxylamine was considerably higher than that of BHT (kinh=1.7×104 dm3.mol-1.s-1) or HALS NOH, but the radical scavenging number (n) of distearyl hydroxylamine was not so high as that reported previously. The high radical-scavenging ability of distearyl hydroxylamine seems to be based on the easier cleavage of the C-N bond of N,N-distearyl nitroxide radical derived from hydrogen abstraction by an alkoxy radical, compared with that of HALS NOH. A new radical scavenging mechanism of distearyl hydroxylamine is proposed based on the observations of electron spin resonance spectroscopy.