Thermodynamics of vaporization of some cyclic perfluorocarbons

The temperature dependence of the saturation vapor pressure of perfluoro-meta-dimethylcyclohexane, (CF3)2C6F10, has been determined by the ebulliometric method in the moderate pressure range from 8.4 to 101.6 kPa. Enthalpies of vaporization have been obtained calorimetrically for perfluorobicyclo(4,4,0)dec(1,6)ene, C10F16, and (CF3)2C6F10 at T = 298.15 K. Densities of C10F16 have been measured in the small temperature range from 293 to 338 K. Critical parameters have been estimated from vapor pressure data and densities for the substances under study and for some mono- and bicyclo-perfluorocarbons investigated earlier. A second-order group additivity method has been applied to predict the vaporization enthalpies of some cyclic perfluorocarbons.