Solubility of d-phenylglycine methyl ester hydrochloride in water and in organic individual or mixed solvents: Experimental data and results of thermodynamic modeling

The solubility of d-phenylglycine methyl ester hydrochloride in water, methanol, ethanol, acetone, ethyl acetate, and toluene as well as in methanol-ethyl acetate and methanol-toluene binary mixtures with different compositions was measured under atmospheric pressure and from 283.15 K to 333.15 K using a dynamic laser method. Experimental data were correlated with the modified Apelblat, combined nearly ideal binary solvent/Redlich-Kister, and nonrandom two-liquid models. Computational results showed that the solubility of d-phenylglycine methyl ester hydrochloride increased monotonically with increasing temperature in individual and mixed solvents. It also increased monotonically with increasing methanol concentration in binary mixtures. The evaluation of model accuracy and applicability demonstrated that all models provided good fits. Changes in the standard enthalpy, entropy, and Gibbs free energy of d-phenylglycine methyl ester hydrochloride upon dissolution were calculated to obtain thermodynamics data. The results showed that the dissolution followed a non-spontaneous and endothermic process, and in most cases enthalpy was the main contributing parameter.