LAUSR

Abstract The solubility knowledge of pharmaceutical compounds in pure solvents and solvent mixtures has a critical role in formulation, separation and purification in the pharmaceutical and chemical industries. In the article ahead, the solid–liquid equilibria measurements for solubility of caffeine in the non-aqueous binary mixtures of N-methyl-2-pyrrolidone (NMP) and isopropanol at different temperatures and atmospheric pressure is measured and the acquired data are fitted to some linear and non-linear cosolvency models including the van’t Hoff, the combined nearly ideal binary solvent/Redlich–Kister (CNIBS/R–K), Jouyban-Acree, Jouyban-Acree-van’t Hoff, and the modified Wilson models. The determined density data of caffeine saturated solutions as another physico-chemical property are also correlated with the Jouyban-Acree model and the results are discussed in detail. The mean relative deviations (MRD%) of the back-calculated solubility data aiming to study the accuracy of the applied models are computed. Moreover, the apparent thermodynamic properties of caffeine dissolution process are also calculated by using van’t Hoff and Gibbs equations.