Thermodynamic modelling for solubility of 5-chloro-1-methyl-4-nitroimidazole in eleven organic solvents from T = (283.15 to 318.15) K

Abstract

Solubilities of 5-chloro-1-methyl-4-nitroimidazole in eleven organic solvents of methanol, ethanol, isopropanol, n-propanol, N-methyl-2-pyrrolidone, ethyl acetate, toluene, acetone, 2-butanone, trichloromethane and 1,4-dioxane were measured by using an isothermal saturation method at temperatures between 283.15K and 318.15K under 101.3kPa. For the temperature range investigated, the solubilities of 5-chloro-1-methyl-4-nitroimidazole in these solvents increased with the increase in temperature. Overall, the mole fraction solubility obeyed the following order from high to low in different solvents: N-methyl-2-pyrrolidone>acetone>2-butanone>trichloromethane>ethyl acetate>1,4-dioxane>methanol>ethanol>toluene>n-propanol>isopropanol. The solubility values obtained for 5-chloro-1-methyl-4-nitroimidazole in the selected solvents were correlated via the λh equation, modified Apelblat equation, NRTL model and Wilson model. The largest value of root-mean-square deviation (RMSD) was 9.20×10−4, and the relative average deviation (RAD), 2.86%. The RAD values obtained with the modified Apelblat equation were smaller than those with the other three models except for the solvents of acetone and ethanol. Generally, the four thermodynamic models were all acceptable for describing the solubility of 5-chloro-1-methyl-4-nitroimidazole in the solvents. Moreover, the mixing Gibbs energy, mixing enthalpy, mixing entropy, activity coefficient at infinitesimal concentration (γ1∞) and reduced excess enthalpy (H1E,∞) were achieved. The solution process of 5-chloro-1-methyl-4-nitroimidazole was spontaneous and favourable in the solvents selected. The solubility values and thermodynamic studies would provide a fundamental basis for optimizing the purification process of 5-chloro-1-methyl-4-nitroimidazole.