VOLUMETRIC PROPERTIES OF THE PHARMACEUTICAL MODEL COSOLVENT SYSTEM 1,4-DIOXANE + WATER AT SEVERAL TEMPERATURES

Abstract

Although the cosolvent system 1,4-dioxane+ water is poisonous, it is widely used in the pharmaceutical sciences as a versatile model for studying drug solubility and some other relevant physicochemical properties in the design of homogeneous dosage forms. For this reason, the excess molar volumes and partial molar volumes of components are investigated from density measurements of the entire range of mass fractions for the 1,4-dioxane + water system at 293.15 K; 298.15 K; 303.15 K; 308.15 K and 313.15 K. The results of excess molar volumes are fitted by Redlich-Kister equation using third degree polynomials and compared with those of literature for other systems. The system exhibits large negative excess volumes (up to – 0.71 cm3 mol–1) probably due to increased interactions like hydrogen bonding between unlike molecules or very large differences in the molar volumes of pure components. The effect of temperature on the different volumetric properties studied is also analyzed. Besides, the volume thermal expansion coefficients are also calculated founding values varying from 2.50 x 10–4 K–1 for pure water up to 1.06 x 10–3 K–1 for pure 1,4-dioxane at 298.15 K.

Keywords

• 1
• 4-dioxane
• water
• binary liquid mixtures
• excess volumes
• partial volumes.