Determination and Correlation of the Solubility of 2-Methyl-4-chlorophenoxyacetic Acid in 12 Pure Solvents at Temperatures from 278.15 to 323.15 K

In this work, the solubility of 2-methyl-4-chlorophenoxyacetic acid (MCPA) was measured in 12 pure organic solvents (ethanol, n-propanol, isopropanol, isobutanol, ethyl formate, methyl acetate, ethyl acetate, n-propyl acetate, n-butyl acetate, acetonitrile, acetone, and toluene) by a gravimetric method at atmospheric pressure and within a temperature range of 278.15-323.15 K. The results demonstrate a trend of increasing solubility of MCPA with rising temperature. Three empirical equations and a theoretical model were used to correlate the solubility data of MCPA, including the modified Apelblat equation, the Van't Hoff equation, the lambda h equation, and the nonrandom two-liquid (NRTL) equation. The solubility values calculated by the four models are in good agreement with the measured data, among which the modified Apelblat model shows the best correlation. Additionally, the mixed thermodynamic properties were calculated based on the NRTL model, where the negative Delta mix G and the positive Delta mix S values indicate that the dissolution process of MCPA is spontaneous and entropy-driven. Furthermore, the solvent effect was investigated by using the Kamlet-Taft Linear Solvation Energy Relationship (KAT-LSER) model.