Synthesis of 1,3,5-Tris(phenylamino) Benzene Derivatives and Experimental and Theoretical Investigations of Their Antioxidation Mechanism

1,3,5-Tris(phenylamino) benzene and a series of its substitution derivatives were synthesized. The structure of the as-synthesized products was confirmed by nuclear magnetic resonance spectroscopy and high resolution mass spectra. Moreover, the antioxidation behavior of 1,3,5-tris(phenylamino) benzene and its substitution derivatives as antioxidants in several ester oils was evaluated by a rotary oxygen bomb test and pressurized differential scanning calorimetry, while theoretical calculations were conducted to examine their antioxidation mechanism. It was found that 1,3,5-tris(phenylamino) benzene exhibits better antioxidation ability at elevated temperature (150 and 210 °C) than commonly used commercial antioxidant diphenylamine. In the meantime, the substitution groups exhibit significant effects on the antioxidation behavior of 1,3,5-tris(phenylamino) benzene and its derivatives. This is because the substituents result in changes in the molecular structure and electronic effect of the as-synthesized products, thereby causing s change in their antioxidation behavior.