Study of the Thermodynamic Properties for Polychlorinated 5,10-Dihydrophenarsazine

Abstract

136 polychlorinated 5,10-dihydrophenarsazine (PCPhZ) in the ideal gas state at 298.15 K and 101.3 kPa have been calculated at the B3LYP/6-31G* level using Gaussian 03 program, and their thermodynamic parameters were obtained. The isodesmic reactions were designed to calculate standard enthalpy of formation (ΔfHө) and standard free energy of formation (ΔfGө) of PCPhZ congeners. The relations of these thermodynamic parameters with the number and position of Cl atom substitution (NPCS) were discussed, and it was found that there exist high correlation between thermodynamic parameters (heat capacity at constant volume (Cvө), entropy (Sө), ΔfHө and ΔfGө) and NPCS. On the basis of the relative magnitude of their ΔfGө, the order of relative stability of PCPhZ congeners was theoretically proposed.