Theoretical Investigations on the Catalytic Antioxidation Mechanism of Diarylamine and Coordination Effects of Fe(Ⅲ) and Fe atom

Abstract

Diarylamine radical-trapping antioxidants (RTA) are widely used in petrochemical products. Herein, density functional theory calculations are used to investigate the catalytic oxidation inhibition mechanism of high-effective antioxidant diarylamine (Ar2NH). The coordination effects of Fe(Ⅲ) and Fe atom on the antioxidation is also investigated. The results indicated that the activation of Ar2NH is through reacting with ROO•, and oxygen may serve as a catalyst to participate in the reaction. Ar2NOR can decompose by transferring its β-site hydrogen to ROO• radical, resulting in the formation of Ar2N•. However, the thermal decomposition of Ar2NOR is difficult. The resulted Ar2N• can react with an R• radical to regenerate Ar2NH which reenter in the reaction system to complete the catalytic cycle. The detailed catalytic mechanism is feasible which could interpret the high efficiency of Ar2NH preferably. What’s more, the coordination of Fe(Ⅲ) and Fe atom could improve the antioxidant performance of Ar2NH by enhancing its radical scavenging ability in practical situations, especially Fe(Ⅲ).