Thermochemical behavior of dissolved Carboxylic Acid solutes: Part 2 - Mathematical Correlation of Ketoprofen Solubilities with the Abraham General Solvation Model

摘要

The Abraham general solvation model is used to calculate the numerical values of the solute descriptors for ketoprofen from experimental solubilities in organic solvents. The mathematical correlations take the form of log(C_S/C_W) = c + r·R_2 + s·π_2~H + a·Σα_2~H + Σβ_2~H + v·V_x log(C_S/C_G) = c + r·R_2 + s·π_2~H + a·Σα_2~H + Σβ_2~H + l·log L~(16) 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, R_2 is the solute excess molar refraction, V_x is McGowan volume of the solute, Σα_2~H and Σβ_2~H are measures of the solute hydrogen-bond acidity and hydrogen-bond basicity, denotes the solute dipolarity/polarizability descriptor and L(16) is 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. We estimate R_2 as 1.6500 and calculate V_x as 1.9779, and then solve a total of 19 equations to yield π_2~H = 2.260, Σα_2~H = 0.550 and Σβ_2~H = 0.890. These descriptors reproduce the 19 observed log(C_S/C_W) values with a standard deviation of only 0.123 log units. The log(C_S/C_G) correlation could not be used in the present study because of both lack of experimental vapor pressure data for ketoprofen at 298.15 K, and lack of the Ostwald partition coefficient for ketoprofen into hexadecane.