Solubility and thermodynamic properties of azlocillin in pure and binary solvent systems

Abstract

The solubility data of azlocillin (ALPC) in nine mono-solvents (methanol, ethanol, isopropanol, methyl acetate, ethyl acetate, isopropyl acetate, acetone, acetonitrile, tetrahydrofuran) and two different binary solvent systems (methanol + isopropanol, ethanol + isopropanol), under atmospheric pressure, were experimentally measured via a static gravimetric method in the temperature range from 278.15 K to 323.15 K. According to the experimental results, it could be found that the solubility of ALPC in all the tested pure and binary solvent systems increased with the rise of temperature at the measurable ranges. The solubility order of ALPC in the nine mono-solvents is generally ranked as: (ethanol or tetrahydrofuran) > acetone > (methanol or acetonitrile) > methyl acetate > ethyl acetate > isopropanol > isopropyl acetate. The solubility data of ALPC in both binary solvent systems increase with the increasing of mole fraction of methanol or ethanol. The modified Apelblat equation, λh equation, and NRTL model were applied to correlate the experimental solubility data of ALPC in pure and mixed solvent systems while the CNIBS/R-K model was also used for the mixed solvent systems. Finally, the mixing and dissolution thermodynamic properties of ALPC in the studied systems were calculated by the NRTL model and were analyzed. It was found that the mixing and dissolution processes of ALPC in the tested systems were spontaneous, endothermic and entropy-driven.