多氯联苯醚的结构参数和热力学性质的密度泛函理论研究  

DFT Study on the Structural Parameters and Thermodynamic Properties of Polychlorinated Diphenyl Ethers

作　　者：曾小兰[1] 柳红霞[1] 刘红艳[1] 

机构地区：[1]桂林工学院材料与化学工程系

出　　处：《化学学报》2007年第17期1797-1806,共10页Acta Chimica Sinica

基　　金：国家自然科学基金(No.20477018)资助项目.

摘　　要：采用密度泛函理论(DFT)方法在B3LYP/6-31G*水平上对209个多氯联苯醚(PCDEs)系列化合物进行了全优化和振动分析计算,得到各分子的结构参数和热力学性质,并研究了这些参数与氯原子的取代位置及取代数目(NPCS)之间的关系.结果表明:分子平均极化率(α)、焓(H)、自由能(G)、恒容热容(CVs)和熵(S)与NPCS之间有很强的相关性(相关性系数r2分别为0.9955,1.0000,1.0000,0.9918,0.9995),分子体积(Vm)和最高占据轨道能(EHOMO)与NPCS也有较好的相关性,相关性系数r2分别为0.9735和0.9362.设计等键反应,计算了PCDEs系列化合物的标准生成热(△fH)和标准生成自由能(△fG).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.Fully optimized calculation and frequency analysis of 209 polychlorinated diphenyl ether （PCDE） compounds were carried out using DFT method at the B3LYP/6-31G＊ level and their structural and thermodynamic parameters were obtained. The relation of these parameters with number and position of C1 atom substitution （Npcs） was studied and it was found that there existed high correlation between molecular mean polarizability （a）, enthalpy （H^（-））, free energy （G^（-））, heat capacity at constant volume （ Cv^s ） or entropy （S^（-）） and Npcs （correlative coefficients being 0.9955, 1.0000, 1.0000, 0.9918 or 0.9995 respectively）. It was also found that molecular volume （Vm） and the energy of the highest occupied molecular orbital （EHoMo） have good correlation with Npcs and correlative coefficients r^2 were 0.9735 and 0.9362 respectively. The isodesmic reactions were designed to calculate standard enthalpy of formation （△fH^（-）） and standard free energy of formation （△fG^（-）） of PCDE congeners. The order of relative stability of PCDE congeners was theoretically proposed based on the relative magnitude of their △fG^（-）

关 键 词：多氯联苯醚 密度泛函理论(DFT) 氯原子取代位置 结构参数 热力学性质 相对稳定性 

分 类 号：O621.1[理学—有机化学]