苯及其衍生物的密度泛函理论研究

摘要

Density functional theory B3LYP with 6-31G* basis set has been used to optimize the geometries of benzene and its derivatives .The stability ,Mulliken charges and vibrational frequencies have been investiga-ted.The results show that stability is intensive when the benzene ring is replaced by -CH3、 -NH2、-OH、-OCH3 .Electrophilic substitution could occur in ortho -position carbon and para -position carbon which have higher negative charge.C -H stretching vibration will move toward the short wavelength with -CH3 substituent.And C -H stretching vibration will move toward the long wavelength with -NH2、 -OH、-OCH3 .The regularity between benzene and its derivatives has been found ,thus providing theoretical guid-ance for experimental research .%　　采用密度泛函理论B3LYP/6-31G倡方法对苯及其衍生物进行结构优化，并对其稳定性、电荷布局、振动频率进行分析讨论。结果表明：当苯环上的一个氢被-CH3、-NH2、-OH、-OCH3取代后，其结构稳定性依次增强；邻对位碳原子具有较高的负电荷，所以邻对位易于发生亲电取代反应；取代基为-CH3的C -H 伸缩振动向短波方向移动，-NH2、-OH、-OCH3使 C -H 伸缩振动向长波方向移动。找到了苯及其衍生物之间存在的规律，为实验研究提供理论指导。