Vapor-Liquid Equilibrium for the Hexamethyldisiloxane-r- Propyl Alcohol System.

Abstract

Vapor-liquid equilibrium data have been determined at 750 mm. of Hg pressure for the n-propyl alcohol-hexamethyldisiloxane system using a modified Othmer still. A thermodynamic evaluation proved the data to be consistent. A minimum boiling azeotrope is formed at 0.495 mole fraction silicone and a temperature of 85.15°C. Density-composition data also have been determined for this binary system.Hexamethyldisiloxane is the simplest of the methyl silicones, which are being used as coatings, impregnante, and water repellante. Since they may be applied from solvent solutions, knowing the properties of these solutions is necessary. The data, presented herein, are part of a continuing study to determine these properties.A review of the literature indicates that neither the density-composition data nor the vapor-liquid equilibrium data for this system have been reported. The data, determined at 750 mm. of Hg pressure, deviate considerably from liquid phase ideality. A minimum boiling azeotrope is formed by this system at 0.495 mole fraction hexamethyldisiloxane and at a temperature of 85.15°C. A thermodynamic evaluation proved the data to be consistent.

Liquid-vapor equilibriums in binary systems of hexamethyldisiloxane-1-butanol, -2-butanol, and -2-methyl-1-propanol

“…A variety of physicochemical techniques, including ebulliometry, have been employed for studying intermolecular interactions. As there are only a few reports in the literature (1)(2)(3) on molecular interaction between hexamethyldlsiloxane and alcohols, this work has been confined to the measurements of vapor pressures and boiling points in the systems including hexamethyldlsiloxane and isomeric butanols. Results of these measurements can provide a basis for evaluation of the nature of deviation of the systems from ideal state.…”