Enthalpies of Glycine Protonation in Water–Acetone and Water–Ethanol Solvents

Abstract

Heat effects of the reaction of glycine protonation  at  298 K  in  water–ethanol  (µ = 0.1 (NaClO₄)) and water–acetone (µ = 0.3 (NaClO₄)) solvents of various compositions are determined via calorimetry. The enthalpies of the resolvation of glycinium ions in aqueous solutions of ethanol and acetone are calculated using the literature data. It is established that a minor change in the heat effect of the reaction of glycine protonation in water–ethanol and water–acetone solvents is associated with the mutual compensation of the enthalpies of proton, glycinium-ion, and glycine resolvation in these media. It is shown that the contribution from the enthalpy component to the change in the Gibbs energy of this reaction is insignificant.