Molar excess enthalpies, volumes, and Gibbs free energies of methanol – isomeric butanol systems at 25 °C

The vapor–liquid equilibria of the 4 binary systems formed by mixing methanol with n-butanol, isobutanol, sec-butanol, and tert-butanol were investigated at 25 °C in a dynamic still with circulation. The results were used to calculate the molar excess Gibbs free energies. For the three systems containing isobutanol, sec-butanol, or tert-butanol, molar excess enthalpies and volumes were also determined (mainly at 25 °C) by direct calorimetric and dilatometric techniques. The behavior of the excess properties is discussed with reference to differences in the hydrogen bonding and in the shapes of the component molecules.