Interfacial Properties of tert-Butyl Alcohol Solutions and Their Relation to Clathrate Formation

Abstract

According to a previous report (Glinski, J.; et al. J. Chem. Phys. 1996, 102, 8816) the surface entropy of the tert-butyl alcohol/water system shows a maximum with respect to solute concentration. Such a maximum was formerly related to the formation of clathrate structures at the interfacial region. However, more complex behavior has also been observed in other aqueous systems. It is currently believed that the surface entropy maxima may reflect structural changes similar to a phase transition and specific interactions between solute molecules. To test the clathrate hypothesis, the thermodynamic properties of tert-butyl alcohol at water, heptane, and water/heptane interfaces were evaluated. For this purpose, the variation of the surface/interfacial tension as a function of temperature and solute concentration was measured, employing Wilhelmy plate and Du Nouy ring techniques. In aqueous tert-butyl alcohol solutions, the maximum of entropy found by Glinski et al. is reproduced. The absence of a large maxim...