Thermodynamic properties of fluorine compounds. Part V. Vapour pressures of pentafluorobenzene, chloropentafluorobenzene, 2,3,4,5,6-pentafluorotoluene, and pentafluorophenol

Abstract

The vapour pressures of pentafluorobenzene and of pentafluorophenol have been measured in the range 200–1000 mm. Hg, and the results have been fitted by Antoine equations. The vapour pressures of chloropentafluorobenzene and 2,3,4,5,6-pentafluorotoluene have been measured over a longer range, 40–1500 mm. Hg, in apparatus modified so as to be more satisfactory at low pressures, and these results have been used for the comparison of five equations which have been recommended for the representation of vapour pressures. For these two compounds the three-constant Antoine equation is as satisfactory over the extended range as other equations containing four constants. Normal boiling points and heats of vaporization at the normal boiling point have been calculated for all four compounds.