Allyl- and Propenyl-Substituted Nitrogen-Containing Aromatic Compounds as Antioxidants for Hydrocarbons

A series of multifunctional nitrogen-containing phenolic compounds were synthesized via the Mannich reaction of 2-allyl- and 2-propenylphenols with aldehydes (formaldehyde or benzaldehyde) and various amines (aniline, n-propylamine, n-hexylamine, n-octylamine, or diethylamine). The products were characterized by NMR, IR spectroscopy, and elemental analysis. These compounds were evaluated as antioxidants for isopropylbenzene (cumene) at concentrations of 5 × 10–5 mol/L under autoxidation conditions and 5 × 10–4 mol/L in oxidation initiated by azobisisobutyronitrile. In this model system, the synthesized compounds exhibited high antioxidant activity, and the reaction kinetics in their presence outperformed those of the commercial antioxidant, 2,6-di-tert-butyl-4-methylphenol (ionol).