Squalene, a model compound of polyisoprene or natural rubber, was employed as solvent to study the reaction between ozone and a series of N,N′-substituted-p-phenylenediamines (PPDs) and other secondary aromatic amines. In all cases, it was found that nitroxyl radicals were formed nearly quantitatively by the action of ozone on the squalene solutions containing dissolved the selected additives. The resulting nitroxyl radicals from PPDs or from other secondary aromatic amines were easily detected by electron spin resonance spectroscopy at room temperature and the isotropic and anisotropic hyperfine interaction constants of the said nitroxides were determined. The FT-IR spectroscopy was employed to show the easy oxidation of unprotected squalene when exposed to an ozone stream, while in presence of PPDs, ozone is quantitatively scavenged by the PPDs forming the resulting nitroxides and protecting completely squalene from ozonolysis reactions. The nitroxyl radicals formed by PPDs or secondary aromatic amine ozonation exert a permanent antioxidant activity entering in a redox cycle already known to ensure a long flex fatigue life or the given rubber compound.

中文翻译：

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臭氧作用于含有仲芳胺抗氧化剂的角鲨烯上形成氨氧基（硝酰基或硝基氧）自由基

以聚异戊二烯或天然橡胶的模型化合物角鲨烯为溶剂，研究臭氧与一系列N , N'-取代-p的反应。-苯二胺 (PPD) 和其他仲芳胺。在所有情况下，发现通过臭氧对含有溶解的选定添加剂的角鲨烯溶液的作用，几乎定量地形成了硝酰基自由基。在室温下通过电子自旋共振光谱很容易检测到来自 PPD 或其他仲芳胺的硝酰基自由基，并确定了所述硝基氧的各向同性和各向异性超精细相互作用常数。FT-IR 光谱用于显示未受保护的角鲨烯在暴露于臭氧流时容易氧化，而在 PPD 存在下，臭氧被 PPD 定量清除，形成所得的氮氧化物并完全保护角鲨烯免受臭氧分解反应。