Thermodynamic properties of polybrominated thianthrenes by density functional theory
The thermodynamic properties of 75 polybrominated thianthrenes (PBTAs) in the ideal gas state at 298.15 K and 1.013 ×105 Pa were calculated at the B3LYP/6-31G level using Gaussian 98 program and their thermodynamic parameters were obtained.The isodesmic reactions were designed to calculate standard enthalpy of formation and standard free energy of formation of PBTAs congeners.The relations of these thermodynamic parameters with the number and position of Br atom substitution were discussed, and it was found that there existed high correlation between thermodynamic parameters (thermal correction to energy, heat capacity at constant volume, entropy,standard enthalpy of formation and standard free energy of formation) and number and position of Br atom substitution.On the basis of the relative magnitude of their standard free energy of formation, the order of relative stability of PBTA congeners was theoretically proposed.