This paper reports
thermodynamic properties of phase transitions
of 2,4,6-trichloro and 2,4,6-tribromo anisoles and of 2,4,6-tribromophenol.
The vapor pressures of both crystalline and liquid phases (including
supercooled liquid) of the three compounds were measured, respectively,
in the temperature ranges T = (297.1 to 368.3) K, T = (330.7 to 391.7) K, and T = (336.5
to 401.7) K, using a static method based on capacitance diaphragm
manometers. Moreover, the sublimation vapor pressures of 2,4,6-tribromophenol
were also measured in the temperature interval (307.2 to 329.2) K,
using a Knudsen mass-loss effusion technique. The standard molar enthalpies,
entropies, and Gibbs energies of sublimation and of vaporization,
at reference temperatures, were derived from the experimental results
as well as the (p,T) values of the
triple point of each compound. The temperatures and molar enthalpies
of fusion of the three benzene derivatives were determined using differential
scanning calorimetry and were compared with the values derived indirectly
from the vapor pressure measurements. The thermodynamic results were
discussed together with the available literature data for 2,4,6-trichlorophenol.
To help rationalize the phase behavior of these substances, the crystallographic
structure of 2,4,6-tribromophenol was determined by single crystal
X-ray diffraction.