Role of solubility and solvation thermodynamics on the stability of l-phenylalanine in aqueous methanol and ethanol solutions

Abstract

The solubilities of l-phenylalanine in aqueous alcohols such as methanol and ethanol were applied to find various solvation thermodynamic parameters like transfer Gibbs free energies and transfer entropies of solutions. The estimated results were correlated with other solvation and interaction parameters such as transfer free energy due to cavity forming interactions, dipole-dipole interactions, transfer enthalpy and total transfer free energy to find the actual transfer Gibbs free energies and entropies owing to chemical nature of interactions in solutions. These chemical transfer Gibbs interaction parameters were discussed to explain the overall stability of l-phenylalanine in pure solvents, aqueous methanol and ethanol solutions. In addition various thermophysical factors like molar density, molar mass, molar volume, isothermal expansibility and apparent dipole moment of aqueous cosolvent systems were also measured at 298.15 K.