Ternary System Phase Diagram Determinations Concerning Potassium Electrolyte Influence on Aqueous Solutions of Dioxane or Tetrahydrofuran

Abstract

Phase diagrams, at 25°C, were determined for potassium acetate-water-dioxane, potassium acetate-water-tetrahydrofuran, and potassium chloride-water-tetrahydrofuran. Po tassium acetate exceeded potassium chloride in its capacity to stratify aqueous solutions of either dioxane or tetrahydro furan. Kobsev's (1) investigations revealed that the greater the solubility of an alkali metal salt, the greater its salting -out effect. The relative order of the water solubilities of the salts studied are potassium acetate >> potassium chloride. More potassium acetate is required to cause stratification in aqueous dioxane than is necessary to obtain the same results in aqueous tetrahydrofuran. It is proposed that, in com parison to dioxane, tetrahydrofuran forms a weaker associa tion with water and, hence, the cations can more easily break these bonds causing liquid-phase separation.Hphe phenomena which gave rise to this study were first brought to the χ attention of Η. K. Zimmerman, Director of Carbohydrate Research at the University of the Pacific, by research workers in peptide chemistry where the potassium hydroxide-water-dioxane system was used in the saponification of esters. He directed that this method be used by his 0-8412-0428-4/79/33-177-177$05.00/l