Solubility determination and thermodynamic modeling of 2,4-dinitroaniline in nine organic solvents from T = (278.15 to 318.15) K and mixing properties of solutions

Abstract

The solubility of 2,4-dinitroaniline in nine organic solvents of methanol, ethanol, acetone, acetonitrile, n-propanol, toluene, isopropanol, ethyl acetate and 1-butanol was determined experimentally by using the isothermal saturation method over a temperature range from (278.15 to 318.15)K under 101.1kPa. For the temperature range studied, the solubility of 2,4-dinitroaniline in the solvents increased with a rise of temperature. At a specific temperature, the mole fraction solubility is lowest in toluene, and largest in acetone. The solubility order of 2,4-dinitroaniline is acetone>ethyl acetate>acetonitrile>1-butanol>ethanol>methanol>(n-propanol, isopropanol)>toluene. The modified Apelblat equation, λh equation, Wilson model and NRTL model were employed to correlate the solubility of 2,4-dinitroaniline in the solvents studied. The maximum values of root-mean-square deviation (RMSD) and relative average deviation (RAD) were 3.76×10−4 and 1.44%, respectively. The values of RAD obtained with the modified Apelblat equation were smaller than those with the other three models for a certain solvent. Generally, the four thermodynamic models were all acceptable for the systems of 2,4-dinitroaniline in these solvents. Furthermore, the mixing Gibbs energy, mixing enthalpy, mixing entropy, activity coefficient at infinitesimal concentration (γ1∞) and reduced excess enthalpy (H1E,∞) were computed. The solution process of 2,4-dinitroaniline was spontaneous and endothermic in the solvents. The solubility determined and thermodynamic studies would be very helpful for optimizing the purification process of 2,4-dinitroaniline.