Solubility Measurement, Correlation, Hansen Solubility Parameters, and Solvent Effect of 4-Isopropylbenzoic Acid in Twelve Pure Solvents at Temperatures from 278.15 to 323.15 K

Abstract In this study, the gravimetric method was applied to measure the solubility of 4-isopropylbenzoic acid in 12 pure solvents (2-methoxyethanol, 2-ethoxyethanol, 2-propoxyethanol, 2-butoxyethanol, methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, isobutyl acetate, acetonitrile, and N,N-dimethylformamide (DMF)) at the temperature range of 278.15–323.15 K under atmospheric pressure. The experimental results showed that the solubility of 4-isopropylbenzoic acid had a significant positive correlation with temperature, and the mole fraction solubility (x) order of 4-isopropylbenzoic acid at the temperature of 298.15 K was: DMF (0.4498) > 2-propoxyethanol (0.2474) > 2-butoxyethanol (0.2382) ≈ 2-ethoxyethanol (0.2371) > 2-methoxyethanol (0.2242) > ethyl acetate (0.1801) > methyl acetate (0.1461) > isobutyl acetate (0.1391) > propyl acetate (0.1231) ≈ butyl acetate (0.1202) > isopropyl acetate (0.1114) > acetonitrile (0.02216). The experimental solubility data correlated well with calculated ones from the modified Apelblat equation, the van’t Hoff equation, and the Yaws equation. Based on the principle of similar compatibility, the law of solubility and miscibility of 4-isopropylbenzoic acid in pure solvents were discussed through Hansen solubility parameters and solvent effects for predicting solubility behavior.