Thermodynamics Research Center / ThermoML | Journal of Chemical and Engineering Data

ABSTRACT

The phase diagrams of pyrrole with benzene, cyclohexane, and hexane have been measured at ambient pressure by a dynamic method in a range of temperatures from (240 to 315) K. The simple eutectic system was observed with complete miscibility in the liquid phase for benzene. An immiscibility gap has been observed in the systems of {pyrrole (1) + cyclohexane or hexane (2)}. The upper critical solution temperatures (UCSTs) were observed for these two systems at (285.2 and 314.2) K for cyclohexane and hexane, respectively. The diagrams of phase equilibria have been correlated using the Wilson and the nonrandom two-liquid (NRTL) equation. The isothermal densities of pyrrole as a function of pressure was measured. Densities and excess molar volumes, VmE have been determined for pyrrole with benzene and cyclohexane over temperature range (298.15 to 338.15) K and ambient pressure. The densities of {pyrrole (1) + hexane (2)} mixture was not determined because of the problem of two phases up to 314.2 K. The temperature and composition dependences were described by linear or polynomial correlation. Excess molar volumes were calculated and correlated by the Redlich-Kister polynomial expansion. These systems exhibit negative excess molar volumes, VmE. Volume expansivity, a, and excess volume expansivity, aE, were described in functions of temperature and composition. Our experimental data of VmE were used for the description of the excess molar enthalpy, HmE, for these systems with the Prigogine-Flory-Paterson (PFP) model. Negative VmE and HmE observed in these systems are probably attributed to the p-p interactions between the aromatic rings of pyrrole and benzene for the {pyrrole (1) + benzene (2)} mixture and by the high packing effects for the {pyrrole (1) + cyclohexane (2)} mixture.