多溴代二苯胺热力学性质的密度泛函理论研究

在B3LYP/6-31G*水平上对209个多溴代二苯胺(PBDPA)系列化合物进行了全优化和振动分析计算, 得到各分子在298.15 K, 101.3 kPa标准状态下的热力学参数. 设计等键反应, 计算了PBDPA系列化合物的标准生成热(ΔfHÖ)和标准生成自由能(ΔfGÖ). 研究了热力学参数SÖ与溴原子的取代位置及取代数目(NPBS)之间的关系, 结果表明: PBDPA系列化合物的SÖ, ΔfHÖ和ΔfGÖ与NPBS之间有很强的相关性(R2≥0.984). 根据异构体标准生成自由能的相对大小, 从理论上求得异构体的相对稳定性. 以Gaussian 03程序的输出文件为基础, 采用统计热力学程序计算了PBDPA化合物在200 K至1000 K的摩尔恒压热容(Cp,m), 并用最小二乘法求得Cp,m与温度之间的相关方程, 发现Cp,m与T, T－1和T－2之间有着很好的相关性(R2＝1.000).

DFT Study on the Thermodynamic Properties of Polybrominated Diphenylamines

Abstract Fully optimized calculation and frequency analysis of 209 polybrominated diphenylamine (PBDPAs) compounds were carried out by using DFT method at the B3LYP/6-31G* level and their thermodynamic parameters in the ideal gas state at 298.15 K and 101.3 kPa were obtained. The isodesmic reactions were designed to calculate standard enthalpy of formation (ΔfH?) and standard free energy of formation (ΔfG?) of PBDPAs congeners. The relationships of these thermodynamic parameters with the number and the position of Br atom substitution (NPBS) were established, it was found that there exists high correlation between entropy (S?), standard enthalpy of formation (ΔfH?), standard free energy of formation (ΔfG?) and NPBS (R2≥0.984). The stability of PBDPAs congeners was theoretically proposed based on the relative magnitude of their ΔfG?. The values of Cp,m were calculated by using statistical thermodynamics calculation Program at the temperatures between(200 to 1000)K based on Gaussian 03 output files, and obtained relative equation between Cp,m and temperature by the least square method, found that Cp,m and T、T-1、T-2 have a very good relationship(R2=1.000). The isomer which has the highest toxicity may be has three numbers of Br atom according the Vm of PBDPAs.