烷基化芳胺润滑添加剂抗氧抗腐蚀机理的密度泛函理论研究

Density Functional Theory Study on Action Mechanism of Anti-Oxidant and Anti-Corrosive for Alkylated Arylamine Additive

采用量子化学的密度泛函理论计算了8种烷基化芳胺抗氧抗腐蚀添加剂与烷氧自由基(C6H13O.)的结合能以及与铁原子簇的化学吸附作用能,探讨了化合物的结构特征、作用机理、授受电子的性质和取代基效应.结果表明:这些添加剂的HOM O均为带有杂原子的孤对电子的π-分子轨道,HOM O可以与金属原子的LUM O发生相互作用,HOM O的电子转移到金属原子的LUM O上形成配位键和稳定的吸附态;添加剂的LUM O均为苯环的π-共轭体系组成,可与RO.的SOM O相互作用,LUM O接受RO.的电子生成稳定的加成产物,添加剂具有授受电子性质;烷基化芳胺添加剂抗氧抗腐蚀性能与取代基的供电子效应或共轭效应有关,当供电子效应强时可以增加添加剂与RO.的结合能以及与铁原子簇的化学吸附作用能.依据计算结果可以推测8种化合物的抗氧抗腐性能由高到低顺序为:化合物Ⅰ>Ⅵ>Ⅷ>Ⅶ>Ⅲ>Ⅴ>Ⅳ>Ⅱ,计算结果与实验结果一致.

Combination energy of alkylated arylamine to n-hexane oxygen radical（C6H13O·） and chemical adsorption of alkylated arylamine to Fe atom cluster for eight anti-oxidant and anti-corrosive additives have been obtained by density functional theory. Structural characteristics, action mechanism, giving and accepting electron properties, substituent effect are explored. It is indicated that HOMO of the additives are π-molecular orbital with lone pare electron and LUMO of the additives are made up of π-conjugated system of benzene ring. Theoretical studies showed that alkylated arylamine containing phenyl group and N atom of a lone pair electron can not only combine with RO · , but also can react with Fe atom. Action mechanism of anti-oxidant and anti-corrosion is that LUMO of the additives reacts with SOMO of RO · to form stable nucleophilic addition product and to terminate oxygen radical reaction; HOMO of the additives reacts with LUMO of Fe atom, and lone pair electron of HOMO translates more easy to LUMO of iron atom to form chemical adsorption state and oil film on metal surface, which can inhibit oil catalytic degradation and protect metals from corrosion. Anti-oxidant and anti-corrosive ability of the additives are related to giving electron effect and conjugating electron effect. Therefore, according to the calculated results we predict that order of anti-oxidant and anti-corrosive property of eight compounds is as following ： Ⅰ〉Ⅵ〉Ⅷ〉Ⅶ〉Ⅲ〉Ⅴ〉Ⅳ〉Ⅱ ,which is in good argeement with experiment results.