四氯二苯并对二噁英的从头算和密度泛函理论研究

Ab initio and DFT Calculations of Tetrachlorodibenzo - p - dioxins

用HF/6-311G**和B3LYP/6-311G**方法全优化计算22个四氯二苯并对二噁英(简称TCDD)分子,预言了能量最低的异构体不是毒性最大的2,3,7,8-TCDD,而是1,3,6,8-TCDD,这一结论与以前采用AM1和PM3方法得到的结论不同。得到的异构体相对稳定性次序与垃圾焚烧炉中生成的异构体的百分比次序基本一致,说明焚烧炉中产生的TCDD主要受热力学控制。

HF/6-311G** andB3LYP/6-311G** calculations of tetrachlorodibenzo-p-dioxins (TCDDs) predicted that the lowest - energy isomer is not the most toxic 2,3,7,8 - TCDD isomer but 1,3,6,8 - TCDD. This is contrary to the AMI and PM3 prediction which are used for the elucidation of the isomer distribution of the TCDD homologue in combustion - derived samples. The conclusion of stability for various isomers was discussed with respect to their total energies. The comparison of the above conclusion with the observed percentage of TCDDs from the incinerator shows that the distribution of TCDD isomers generated in incinerator is controlled by thermody-namically.