Preferential solvation in mixed solvents Part 8. Aqueous methanol from sub-ambient to elevated temperatures

Abstract

The inversed Kirkwood–Buff integral method is applied to mixtures of water and methanol from -13 to 250°C. Preferential solvation is deduced from these integrals and shown over the entire composition and temperature ranges. The self-preference of water increases with rising temperatures in both water- and methanol-rich mixtures, reaching a limiting value near the critical point of methanol. At the equimolar composition, though, this self-preference reaches a shallow maximum near 150 °C. The methanol self-preference in methanol-rich mixtures is slight, but this hydrophobic effect is considerable at 15 mol% of methanol, reaching a pronounced maximum near 150°C. The effect of the methanol on the structure of the water, the incorporation of water into the structure of methanol, and their changes with increasing temperatures are discussed.