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化学学报
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化学学报 ›› 2006, Vol. 64 ›› Issue (19): 1961-1968. 上一篇    下一篇

研究论文

多溴二苯并呋喃的热力学性质和稳定性的密度泛函理论研究

余菁1, 张幸川1, 王遵尧*,1, 曾小兰2   

  1. (1嘉兴学院生物与化学工程学院 嘉兴 314001)
    (2桂林工学院材料与化学工程系 桂林 541004)
  • 投稿日期:2006-01-10 修回日期:2006-03-30 发布日期:2006-10-14
  • 通讯作者: 王遵尧

Study on the Thermodynamic Properties and Stability of a Series of Polybrominated Dibenzo-furans by Density Functional Theory

YU Jing1; ZHANG Xing-Chuan1; WANG Zun-Yao*,1; ZENG Xiao-Lan2   

  1. (1 School of Biological and Chemical Engineering, Jiaxing University, Jiaxing 314001)
    (2 Department of Material and Chemical Engineering, Guilin Institute of Technology, Guilin 541004)
  • Received:2006-01-10 Revised:2006-03-30 Published:2006-10-14
  • Contact: WANG Zun-Yao

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被引次数

54 | 15

在B3LYP/6-31G*水平上对二苯并呋喃和135个多溴二苯并呋喃系列化合物(PBDF)进行了全优化计算和振动分析, 得到各分子的总能量(ET)、焓(H0)、熵(S0)、自由能(G0)和恒容热容(CV0), 研究了这些参数与溴原子的取代数目及取代位置的关系. 溴原子置换在不同位置时, 使ET, H0和G0数值增加大小次序为: 1(9)＞3(7)＞2(8)＞4(6), 即置换在1(9)位最不稳定; 两个溴原子处在同一苯环时, ET, H0和G0数值也都增加, 增加的顺序为: 邻>>间＞对, 即相互处于邻位最不稳定. 而且有两个溴原子同时取代在1和9位时, 使H0和G0的数值的增加比取代在邻位、间位和对位时的增加值都大. 每增加1个溴原子, S0增大约40.1 J•mol－1•K－1, CV0增大约16.3 J•mol－1•K－1. 同时, 设计等键反应, 计算了各异构体的标准生成热(Hf0)和标准生成自由能(Gf0). 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, 各异构体组中的稳定性顺序与PCDF系列的稳定性顺序基本一致.

关键词: 多溴二苯并呋喃, 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 (H0), entropy (S0), free energy (G0) and constant volume molar heat capacity (CV0) for dibenzo-furan and 135 polybrominated dibenzo-furans (PBDF), were predicted by fully optimized calculation and frequency analysis at the B3LYP/6-31G* level. In addition, the dependence of these thermodynamic parameters on the number and the position of bromine substitution were discussed. It was suggested that the total energy, enthalpy and free energy of PBDF vary remarkably with the positions of bromine substitution, with the order of decrease of parameter value being 1(9) position＞3(7) position＞2(8) position＞4(6) position. It was also found that the thermodynamic parameters are all increased in the case of the two bromine substitutions on the same aromatic ring, compared with that on two aromatic rings, with the increase effect order being ortho>>meta＞para. Moreover, the increment of the H0 and G0 values of PBDF congeners with both 1 and 9 positions substituted with bromine is larger than the corresponding values of that with substitution at ortho position, meta position and para position respectively. With addition of each bromine atom to PBDF, the increased values of S0 and CV0 are about 40.1 and 16.3 J•mol－1•K－1 respectively. The isodesmic reactions were designed for calculating standard formation heat (Hf0) and standard free energy (Gf0) of PBDF. The relative stability of PBDF congeners was theoretically proposed in this work. The most stable and unstable isomer in different isomer groups of PBDF are similar to those for PCDF.

Key words: polybrominated dibenzo-furan, DFT method, thermodynamic property, relative stability