Temperature dependence of the structure of a 0.06 mole fraction tertiary butanol-water solution

Abstract

Hydrogen/deuterium isotopic substitution neutron diffraction techniques have been used to measure the solute–solute, solute–solvent and solvent–solvent structural correlation functions in a 0.06 mole fraction solution of tertiary butanol in water. The measurements were made at two temperatures, 25 °C and 65 °C. Data analysis to the level of intermolecular orientational correlation functions was performed by the Empirical Potential Structure Refinement (EPSR) technique in combination with a spherical harmonic coefficient analysis. The results reveal in particular a subtle temperature dependence of the intermolecular structure of the solvent water. This structural perturbation is suggestive of a hydrophobic hydration induced, local density enhancement in the solvent water that could relate to the entropic driving force underlying the hydrophobic interaction mechanism.