Solubility of codeine phosphate in N-methyl-2-pyrrolidone + 1-propanol mixtures at different temperatures.

The purpose of the current study is the investigation of the solubility data and thermodynamic properties of codeine phosphate in mixtures of N-methyl-2-pyrrolidone and 1-propanol under atmospheric pressure at 293.2–313.2 K. Positive correlations of the solubility with temperature and N-methyl-2-pyrrolidone ratio were observed. The measured data were correlated using some mathematical models, and their reliability was studied by computing the mean relative deviations of the back-calculated values. The density values of codeine phosphate saturated solutions were also measured and correlated using the Jouyban–Acree model. Furthermore, the apparent thermodynamic properties of the codeine phosphate solubilisation (e.g. standard enthalpy, entropy, and Gibbs free energy) are also computed based on Gibbs and van't Hoff equations and reported. [ABSTRACT FROM AUTHOR]