AIR-WATER PARTITIONING AND AQUEOUS SOLUBILITY OF PHENOLS

Relative volatilities from highly dilute aqueous solutions were measured for phenol, 2-methylphenol, 3-methylphenol, 4-methylphenol, 2,3-dimethylphenol, 2,4-dimethylphenol, 2,5-dimethylphenol, 2,6-dimethylphenol, 3,4-dimethylphenol, and 3,5-dimethylphenol at three temperatures covering the temperature range 75-100 degrees C with a vapor-liquid equilibrium circulation still. Because of the high dilution of solutions involved, the limiting relative volatility could be determined simply as a ratio of UV absorbances of the equilibrium vapor-phase and liquid-phase samples. In addition, the aqueous solubilities of 2,3-dimethylphenol, 2,5-dimethylphenol, 2,6-dimethylphenol, 3,4-dimethylphenol, and 3,5-dimethylphenol were measured at 20 degrees C by a conventional batch contacting technique with analysis by UV spectroscopy. The vapor-liquid equilibrium data and solubilities measured in this work and some additional data from the literature were used to obtain limiting activity coefficients gamma(1)(infinity), Henry's law constants H, and air-water partition coefficients K-aw covering a range of temperatures from the ambient to the normal boiling point of water. For each phenol, the temperature dependence of gamma(1)(infinity), H, and K-aw was used to estimate the limiting partial molar excess enthalpies and enthalpies of hydration. The values of gamma(1)(infinity), H, and K-aw for isomeric cresols and xylenols were found to be well correlated with their normal boiling temperatures.