Solubilities of 5,10,15,20-Tetraphenylporphyrin and 5,10,15,20-Tetra(p-chlorophenyl)porphyrin in Binary N,N-Dimethylformamide + Water Solvent Mixtures

The mole fraction solubilities of 5,10,15,20-tetraphenylporphyrin (TPP) and 5,10,15,20-tetra(p-chlorophenyl)porphyrin (p-ClTPP) in binary system N,N-dimethylformamide (DMF) + water solvent mixtures were measured at atmospheric pressure by using the static method. The temperature and effects of mole fraction of DMF in the solvent mixtures on solubility were studied. The results show that the solubilities of TPP and p-ClTPP increase with the increasing temperature for a certain solvent composition, and the solubilities show a maximum in pure DMF, then the solubilities decrease when the water was added to the system. The experimental data were correlated with modified Apelblat equation. The solubilities calculated by the model were in good agreement with experimental observations. Thermodynamic parameters such as dissolution enthalpy, isobaric heat capacity and Gibbs energy were obtained from the solubility data by using the Clark–Glew equation together with the modified Apelblat equation. The result demonstrated that the dissolving process of TPP and p-ClTPP in DMF + water solvent mixtures is endothermic and not spontaneous.