Determination and Correlation of the Solubility of 1,3-Cyclohexanedione Form I in Fourteen Pure Solvents at Temperatures from 288.15 to 333.15 K

The solubility of 1,3-cyclohexanedione form I (CHD1) was determined using a gravimetric method, spanning temperatures from 288.15 to 333.15 K across 14 solvents (acetonitrile, tetrahydrofuran, toluene, chloroform, propanone, 2-butanone, methyl acetate, ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, ethyl formate, ethyl propionate, and ethyl butyrate). The experimental solubility data showed a gradual increase with rising temperature. Three empirical models (modified Apelblat equation, the Van't Hoff equation, and the λh equation) and one theoretical model (NRTL model) were employed to correlate and fit the solubility data of CHD1. The calculated solubility values from all four models were in good agreement with the measured data, with the modified Apelblat equation providing the best correlation. Further, the thermodynamic properties of CHD1 in 14 solvents were calculated, which means the mixing processes of CHD1 are spontaneous and entropy-driven. Besides, solvent properties were studied to gain insights into the solubility behavior of CHD1 in different solvents.