Thermochemistry of Chlorobenzenes and Chlorophenols:  Ambient Temperature Vapor Pressures and Enthalpies of Phase Transitions

This work has been undertaken in order to obtain additional data on vapor pressures of chlorobenzene derivatives and to develop the group-additivity values necessary for predicting their vaporization enthalpies at the reference temperature T = 298.15 K. Molar enthalpies of sublimation and of vaporization of hexachlorobenzene and of mono-, di-, tri-, and pentachlorophenol were obtained from the temperature dependence of the vapor pressure measured by the transpiration method. Thermochemical investigations of chlorobenzenes and chlorophenols available in the literature were collected and combined with our own experimental results to obtain their reliable standard molar enthalpies of vaporizaton at T = 298.15 K. The COSMO-RS procedure has been used for a priori prediction of the vapor pressures and vaporization enthalpies of the whole data set of chlorobenzenes and chlorophenols. The new results help to resolve uncertainties in the available thermochemical data on chlorobenzenes and chlorophenols studied.