Water as a solute in aprotic dipolar solvents. 1. D2O–H2O solute isotope effects on the enthalpy of water dissolution in acetone, tetrahydrofuran and 1,4-dioxane at 298.15 K

The enthalpies of solution of H2O and D2O in tetrahydrofuran (THF), 1,4-dioxane (DO) and acetone (AC) were measured calorimetrically at 298.15 K. Standard (at the infinite dilution) enthalpies of solution, along with D2O–H2O solute isotope effects on the quantity in question, were calculated. The enthalpies of the solute dissolution were found to be positive by sign and decreasing in magnitude on going from DO to AC and THF, whereas the corresponding solute isotope effects change in a consequence THF > AC > DO. It was concluded that the enthalpic D2O–H2O effects of water dissolution (solvation) are connected with both the donor-accepting ability and structure-packing peculiarities of the aprotic dipolar solvents compared.