Solubility of crystalline nonelectrolyte solutes in organic solvents: mathematical correlation of 4-chloro-3-nitrobenzoic acid and 2-chloro-5-nitrobenzoic acid solubilities with the Abraham solvation parameter model

The Abraham solvation parameter model is used to calculate the numerical values of the solute descriptors for both 4-chloro-3-nitrobenzoic acid and 2-chloro-5-nitrobenzoic acid from experimental solubilities in organic solvents. The mathematical correlations take the form of log(C-S/C-W) = c + e center dot E + s center dot S + a center dot A + b center dot B + v center dot V log(C-S/C-G) = c + e center dot E + s center dot S + a center dot A + b center dot B + l center dot L where C-S and C-W refer to the solute solubility in the organic solvent and water, respectively, C-G is a gas phase concentration, E is the solute excess molar refraction, V is McGowan volume of the solute, A and B are measures of the solute hydrogen-bond acidity and basicity, S denotes the solute dipolarity/polarizability descriptor, and L is the logarithm of the solute gas phase dimensionless Ostwald partition coefficient into hexadecane at 298 K. The remaining symbols in the above expressions are known solvent coefficients, which have been determined previously for a large number of gas/solvent and water/solvent systems. The Abraham solvation parameter model was found to describe the experimental solubility data of 4-chloro-3-nitrobenzoic acid and 2-chloro-5-nitrobenzoic to within overall standard deviations of 0.067 and 0.113 log units, respectively.