Thermodynamic analysis and molecular simulation of solid–liquid phase equilibrium of isoprenaline hydrochloride in eleven pure solvents at saturation

Abstract

In this research, the solubility of isoprenaline hydrochloride (IPN) in eleven neat solvents was investigated by using experimental and molecular dynamic (MD) simulation analysis approaches. The experimental solubility data of IPN in eleven neat solvents of methanol, 2-methoxyethanol, ethanol, 2-ethoxyethanol, n-propanol, 2-propoxyethanol, n-butanol, 2-butoxyethanol, N, N-dimethylformamide (DMF), N-N-Dimethylacetamide (DMAC) and 1-Methyl-2-pyrrolidinone (NMP) were determined by laser monitoring method at temperature range of (278.15 K–323.15 K) under atmospheric pressure. The solubility values were sensitive to temperature, namely, increased monotonously with increasing temperature. The order of IPN solubility at each temperature point in selected solvents is: DMAC > DMF > NMP > methanol > 2-methoxyethanol > ethanol > 2-ethoxyethanol > 2-propoxyethanol > n-propanol > 2-butoxyethanol > n-butanol. Then, the measurement solubility data was correlated by Two-Suffix Margules model, NRTL-SAC model, Yaws model, λh equation and Apelblat equation, respectively. The derived apparent thermodynamic parameters (ΔdisGo, ΔdisHo, ΔdisSo, ζH, ζTS) shown an entropy-driven, endothermic and spontaneous process of dissolution of IPN in all chosen solvents. And the main contribution of ΔdisGo comes from the positive enthalpy according the larger ζH than ζTS. Furthermore, the results of molecular dynamic simulation revealed using radial distribution function (RDF) analysis, which indicated that interactions of solvent–solute have well fitted with solubility order of IPN in selected solvents.