Equilibrium temperatures for liquid–liquid and solid–liquid
transitions of systems containing sulfolane and propan-1-ol,
butan-1-ol, octan-1-ol or tetradecan-1-ol
were measured by a dynamic method. From butan-1-ol, the mixtures
show an upper critical solution temperature, which increases with the length
of the alcohol. It may attributed to a decreasing of the effective dipole
moment of the alkan-1-ol which markedly decreases the interactions
between unlike molecules. The coexistence curves become shifted to the high
molar fractions of sulfolane in solutions with longer alkan-1-ols,
probably due to size effects. Binary systems of sulfolane with cycloalkanes, n-alkanes,
benzene or toluene, CCl4 or alkan-1-ols were analyzed
in terms of a purely physical model, DISQUAC. The corresponding interaction
parameters are reported. DISQUAC represents fairly well, over a rather wide
range of temperature, a complete set of thermodynamic properties: liquid–liquid
equilibria, LLE, solid–liquid equilibria, SLE, vapor–liquid equilibria,
VLE, molar excess Gibbs energies, GE, molar excess enthalpies, HE
and natural logarithms of activity coefficients at infinite dilution, ln γi∞.
Deviations observed for LLE are typical for mean field theories as calculations
are developed assuming that thermodynamic properties close to the critical
points are analytical. Experimental data show that sulfolane may play the
role of an almost inert diluent, because of the steric hindrance of its globular
nature.