Quantum-chemical modeling of the spatial and electronic structure of asphaltenes containing different numbers of electron-withdrawing substituents used the DFT/B3LYP-6-31G(d,p) method to predict the reactivity of petroleum asphaltenes upon their chemical modification. The change of torsion angle of the polycondensed aromatic asphaltene structure depending on the type of substituent was studied. The electronic structure and electron-density charge distribution over the aromatic carbon atoms were analyzed to determine the predominant direction of electrophilic substitution of the studied asphaltene model structures. A high degree of polycondensation of the asphaltenes and the presence of electron-donating aromatic heterocyclic fragments were shown not to affect significantly the direction of attack of an electrophilic reagent. Introduction of electron-withdrawing substituents decreased the rate of electrophilic substitution.

中文翻译：

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亲电取代反应中沥青质反应性的建模

含有不同吸电子取代基的沥青质的空间和电子结构的量子化学模型使用 DFT/B3LYP-6-31G(d,p) 方法来预测石油沥青质在其化学改性后的反应性。研究了缩聚芳族沥青质结构的扭转角随取代基类型的变化。分析了芳族碳原子上的电子结构和电子密度电荷分布，以确定所研究的沥青质模型结构的亲电取代的主要方向。沥青质的高度缩聚和给电子芳族杂环片段的存在表明不会显着影响亲电试剂的攻击方向。