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化学学报
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化学学报 ›› 2005, Vol. 63 ›› Issue (11): 964-972. 上一篇    下一篇

研究论文

多氯联苯系列化合物的热力学性质和稳定性的密度泛函理论研究

王遵尧*1 2，韩香云2，翟志才2，王连生1   

  1. (1南京大学环境学院 南京 210093)
    (2盐城工学院化工系 盐城 224003)
  • 投稿日期:2004-10-30 修回日期:2005-02-04 发布日期:2010-12-10
  • 通讯作者: 王遵尧

Study on the thermodynamic Property and Relative Stability of a Series of Polychlorinated Biphenyls by Density Functional Theory

WANG Zun-Yao*1,2, HAN Xiang-Yun2, ZHAI Zhi-Cai2, WANG Lian-Sheng1   

  1. (1 School of the Environment, Nanjing University, Nanjing 210093)
    (2 Yancheng Institute of Technology, Yancheng 224003)
  • Received:2004-10-30 Revised:2005-02-04 Published:2010-12-10
  • Contact: WANG Zun-Yao

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1707

被引次数

67

在B3LYP/6-31G*水平上计算了218个多氯联苯系列化合物(PCB), 得到分子总能量(ET)、焓(H°)、熵(S°)、自由能(G°)、零点振动能(EZPV)、恒容热容(CV°)和热能校正值(Eth), 研究了这些参数与氯原子的取代数目及取代位置的关系.氯原子置换在不同的位置使ET, H°和G°数值增加的顺序为: 2(6)位>>3(5)位＞4位, 即置换在2(6)位最不稳定; 两个氯原子在同一苯环比分别处于两个苯环的ET, H°和G°增大, 增加的顺序为: 邻位>>间位＞对位, 即相互处于邻位最不稳定. 每增加1个氯原子, S°增大约30 J•(mol•K)－1, Eth减小约22.2 kJ•mol－1, EZPV减小约25.5 kJ•mol－1, CV°增大约16 J•(mol•K)－1. 根据异构体自由能的相对大小, 从理论上求得异构体的相对稳定性顺序.

关键词: 二噁英, PCB, 密度泛函理论, 热力学性质, 相对稳定性

The thermodynamic function data, including total energy ET, enthalpy H°, entropy S°, free energy G°, zero-point vibration energy EZPV, constant volume molar heat capacity CV° and thermal energy correction Eth for 218 polychlorinated biphenyls (PCB), were predicted by fully optimized calculation at the B3LYP/6-31G* level. In addition, the dependence of these thermodynamic parameters on the number and the position of chlorine substitute was discussed. It was suggested that the total energy, enthalpy and free energy of PCB vary remarkably with the positions of chlorine substitutes, with the order of increase of parameter value being position 2(6)>>3(5)＞4. It was also found that the thermodynamic parameters were all increased in the case of the two chlorine substitutes on the same aromatic ring, compared with that on two aromatic rings, with the increase effect order being ortho>>meta＞para. With addition of each chlorine atom to PCB, the increased values of S° and CV° were about 30 and 16 J•(mol•K)－1, the decreased ones of Eth and EZPV about 22.2 and 25.5 kJ•mol－1, respectively. Also, the relative stability of PCB congeners was theoretically proposed in this work.

Key words: dioxin, polychlorinated biphenyl, DFT method, thermodynamic property, relative stability