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论文类型：期刊论文

发表时间：2014-08-01

发表刊物：JOURNAL OF THEORETICAL & COMPUTATIONAL CHEMISTRY

收录刊物：SCIE、Scopus

卷号：13

期号：5

ISSN号：0219-6336

关键字：Antioxidant; diarylamine; DFT; bond dissociation enthalpy; one-electron oxidation potential; reaction rate constant

摘要：Diarylamines (Ar2NH) are generally used as antioxidants to inhibit or retard the auto-oxidation degradation of lubricating oil by trapping ROO center dot radicals. In the present study, 20 kinds of 4,4'-disubstituted diphenylamine compounds were investigated through density functional theory (DFT) calculations. The results indicate that the N-H bond dissociation enthalpy (BDE) linearly correlates its one-electron oxidation potential, the difference in Mulliken atomic charge on the two atoms of N-H bond, the reaction rate constant of hydrogen transfer from Ar2NH to peroxy radical, and the chemical hardness of the resulted Ar2N center dot radical, respectively. The substitution of alkyl groups (electron-donating groups) decreases the N-H BDE, one-electron oxidation potential and the reaction rate constant, while that of significant electron-withdrawing groups such as -NO2 and -COOCH3 increases these three parameters. The electron-donating groups such as alkyls could improve the antioxidation performance of 4,4'-disubstitued diphenylamines whereas electron-withdrawing groups have the contrary effect. In addition, the frontier molecular orbital of Ar2NH has been also analyzed.