Measurement and Correlation of Solubility of Tetraphenyl Piperazine-1,4-diyldiphosphonate in Mixed Solvents

Abstract

The solubilities of tetraphenyl piperazine-1,4-diyldiphosphonate (TPPDP) in (dichloromethane + ethanol) and (dichloromethane + n-hexane) were measured at temperatures from (283.15 to 308.15) K using a static analytic method. Experimental data are well-represented by the modified Apelblat and (CNIBS)/Redlich–Kister equations for describing the effects of temperature and solvent composition on solubility, respectively. It was found that TPPDP solubility in dichloromethane + n-hexane decreases with the addition of n-hexane, whereas it shows a maximum in dichloromethane + ethanol. The solubility data are well-correlated by Wilson, NRTL, and Jouyban–Acree models, in which Jouyban–Acree model achieves the best fitting results. Based on the modified Apelblat equation, the thermodynamic properties (i.e., the Gibbs free energy, enthalpy, and entropy) of solution in two binary solvent mixtures were derived. The results indicate that the dissolution of TPPDP in all studied cases is not spontaneous and energetic pred...