A comparison of the viscometrically determined hydrations of glucose and tetrahydropyran-2-ylmethanol between 10 and 65°

Intrinsic viscosities in aqueous solutions of glucose and tetrahydropyran-2-ylmethanol have been measured over the temperature range 10–65°. Hydrations were computed by means of the Einstein–Simha equation. For both solutes the hydration decreased markedly with increase in temperature. The hydrodynamic results were compared with thermodynamically computed hydrations based on the thermal expansion of aqueous solutions of glucose, and the Némethy and Scheraga treatment of a non-polar structure former. The agreement was good at low temperatures but for both molecules at higher temperatures the viscometrically computed hydrations were less than those computed thermodynamically.