Effect of 1,4-Dioxane on the Structure of Aqueous t-Butyl Alcohol. Sound Velocity Studies

Abstract

Abstract The structure of aqueous t-butyl alcohol in the water rich region is known to be more structured than pure water. 1,4-dioxane is known to be a weakly hydrophobic solute. The effect of 1,4-dioxane on the structure of aqueous t-butyl alcohol has been studied by fixing the temperature of sound velocity maximum in the ternary solution from the experimentally determined ultrasonic velocity data at different temperatures. The structural contribution to the shift in the temperature of sound velocity maximum of the aqueous t-butyl alcohol solution due to the addition of 1,4-dioxane, [ΔTstr.]exptl, has been found to be positive having the nature of variation similar to that of the effect of 1,4-dioxane on pure water, when the concentration (Xs) of t-butyl alcohol is 0.0075. But, for aqueous t-butyl alcohol solutions having Xs=0.0025 and Xs=0.0046, [ΔTstr.]exptl, has been found to be negative reaching maximum values around X2=0.0045 and there after decreasing with a tendency to become positive at higher concentrations of 1,4-dioxane. These results have been explained in the light of structure breaking and formation of dioxane complexes in the ternary solutions.