%A HOU Hai-Feng, CHEN Bin-Yuan, ZHANG Xue-Sheng, WANG Zun-Yao
%T Comparative Studies on Some Properties of Polyfluorinated, Polychlorinated and Polybrominated Dibenzo-*p*-dioxins
%0 Journal Article
%D 2011
%J Acta Chimica Sinica
%R
%P 617-626
%V 69
%N 06
%U http://sioc-journal.cn/Jwk_hxxb/EN/
%8 2011-03-28
%X The thermodynamic properties of 76 polyfluorinated dibenzo-*p*-dioxins (PFDDs) in the ideal gas state at 298.15 K and 1.013×10^{5} Pa have been calculated at the B3LYP/6-311G** and B3LYP/6-31G* levels using Gaussian 03 program, and it was found that values of standard enthalpy of formation (Δ_{f}*H*^{?}), standard free energy of formation (Δ_{f}*G*^{?}) and standard entropy (*S*^{?}) were broadly consistent under the two base groups. According to the relative magnitude of their Δ_{f}*G*^{?} at the B3LYP/6-311G** level, the relative stability order of PFDD congeners was theoretically proposed. Octanol-water partition coefficients (lg *K*_{ow}) of polybrominated dibenzofurans (PBDDs), polychlorinated dibenzofurans (PCDDs) and PFDDs were calculated by group contributions. Comparison of the properties (including lg *K*_{ow}, *S*^{?}, Δ_{f}*H*^{?} and Δ_{f}*G*^{?}) between PFDDs and PCDDs, PBDDs was carried out. Moreover, the relative rate constants of formation reactions of PFDDs and the values of molar heat capacity at constant pressure (*C*_{p,m}) from 200 to 1800 K for PFDDs congeners were calculated using a statistical thermodynamics calculation program. The temperature dependence relation of *C*_{p,m} was obtained using the least-squares method. The result shows that there exists very good relationship between *C*_{p,m} and temperature (*T*, *T*^{－1} and *T*^{－2}) for almost all PFDD congeners.