Evaluation and correlation of solubility and solvation energetics of DL-phenylalanine and DL-serine in water and aqueous ethylene glycol solutions

Abstract

The saturated solubilities, the standard total transfer free energies (ΔGt0(i)) and entropies (ΔSt0(i)) of transfer of DL-serine and DL-phenylalanine from water to aqueous mixtures of protic ethylene glycol (EG) at 298.15K are reported in the present study. The transfer energies have been determined from the saturated solubility of the amino acids, which have been measured at five equidistant temperatures from 288.15 to 308.15K by ‘analytical gravimetric method’. The chemical parts of free energies (ΔGt, ch0(i)) and entropies (ΤΔSt, ch0(i)) of transfer of the amino acids have been computed by subtracting the cavity effects and dipole-dipole interaction effects from the total transfer free energy. The correlation of saturated solubility and the characteristics of the involved solvation energetics of the amino acids in aquo-organic solvent system are studied and also discussed critically in the present study.