Heats of solution of electrolytes in ethanol and derived enthalpies of transfer from water

Abstract

Heats of solution of 12 1 : 1 electrolytes in ethanol have been determined calorimetrically, and have been extrapolated to zero electrolyte concentration to give ΔH°s values for these electrolytes. Together with literature data for 9 other 1 : 1 electrolytes, these measurements yield a set of single ion enthalpies of transfer from water to ethanol for 11 univalent cations and 6 univalent anions. Using the assumption that ΔH°t(Ph4As+)=ΔH°t(Ph4B–), it is shown that small univalent cations are enthalpically more stable in ethanol than in water, but that the larger tetra-alkylammonium ions are less stable in ethanol. With the same assumption, it is also shown that all the univalent cations and anions studied are of almost the same enthalpy (within about ± 0.5 kcal mol–1) in the three alcohols methanol, ethanol and 1-propanol.