Equilibrium solubility of exo-5,6-dehydronorcantharidin in thirteen pure solvents: Determination, correlation, Hansen solubility parameter and thermodynamic properties

Abstract

This research was focusing on determining the solid-liquid equilibrium solubility of exo-3,6-epoxy-1,2,3,6-tetrahydrophthalic acid anhydride (exo-5,6-dehydronorcantharidin) in thirteen mono-solvents by using laser monitoring approach at diverse temperature and pressure “p = 0.1 MPa”. The results showed that the solubility data of exo-5,6-dehydronorcantharidin in all solvents was positively correlated with experimental temperature. Besides, the mole-fraction solubility values of exo-5,6-dehydronorcantharidin in all considered solvents at “T = 298.15 K” were found maximum in N-methyl-2-pyrrolidinone (0.184) followed by N,N-Dimethylformamide (0.150), acetone (0.0629), acetonitrile (0.0508), methyl acetate (0.0420), 1,4-dioxane (0.0342), ethyl acetate (0.0275), n-propyl acetate (0.0210), isopropyl acetate (0.0191), butyl acetate (0.0172), isobutyl acetate (0.0165), amyl acetate (0.0137) and isoamyl acetate (0.0129). The polarity and Hansen solubility parameter of studied solvents were employed to reveal the affinity and solubility order of exo-5,6-dehydronorcantharidin, and the results indicated that the miscibility between solute and solvent relied on comprehensive effects of multiple factors. Moreover, the obtained solubility data was correlated with Wilson, NRTL, UNIQUAC and NRTL-SAC model. The correlation results showed that the UNIQUAC model can provide the best fitting effect with lower values of average relative deviation (ARD) and root-mean square deviation (RMSD). Finally, thermodynamic mixing and dissolution properties of exo-5,6-dehydronorcantharidin in thirteen neat solvents were calculated based on UNIQUAC model as well as experimental values.