Thermodynamics Research Center / ThermoML | Journal of Chemical Thermodynamics

ABSTRACT

By the isothermal saturation method, the solid-liquid equilibrium of 4-nitro-1,2-phenylenediamine in eleven organic solvents (methanol, ethanol, n-propanol, isopropanol, acetone, 2-butanone, acetonitrile, ethyl acetate, n-butanol, toluene and 1,4-dioxane) was obtained experimentally within temperature range from (283.15 to 318.15) K under atmospheric pressure, and the solubility values of 4-nitro-1,2- phenylenediamine in these solvents were determined by a high-performance liquid chromatography (HPLC). Within this temperature range, the mole fraction solubility of 4-nitro-1,2-phenylenediamine in selected organic solvents increased with increasing temperature. The descending order of the solubility values was as follows: acetone greater than 2-butanone greater than 1,4-dioxane greater than ethyl acetate greater than acetonitrile greater than methanol greater than ethanol greater than isopropanol greater than n-propanol greater than n-butanol greater than toluene. The solubility values for 4-nitro-1,2-phenylenediamine in the selected solvents were correlated and calculated by using the modified Apelblat equation, kh equation, Wilson model and NRTL model. Results showed that the largest values of RAD and RMSD obtained by the four models were 1.53% and 0.83 10 4, respectively. The modified Apelblat equation can correlate the experimental results best according to the result of AIC analysis. Moreover, the mixing properties including the mixing Gibbs energy, mixing enthalpy, mixing entropy, activity coefficient at infinitesimal concentration oc1 1 P and reduced excess enthalpy oHE;1 1 P were calculated. The solution process of 4-nitro-1,2-phenylenediamine is spontaneous and favourable in the selected solvents. Knowledge of solubility and associated thermodynamic studies are important in optimizing the purification process of 4-nitro-1,2-phenylenediamine.