The solubility determination and thermodynamic modeling of cis-3-(2,5-dimethylphenyl)-4-hydroxy-8-methoxy-1-azaspiro[4.5]dec-3-en-2-one (SI-VI) in binary mixed solvents from T = (288.15–328.15) K

The solubility of cis-3-(2,5-dimethylphenyl)-4-hydroxy-8-methoxy-1-azaspiro[4.5]dec-3-en-2-one (SI-VI) in four binary mixed solvents (methanol + water, ethanol + water, acetonitrile + water, and n-propanol + water) was determined within T = (288.15–328.15) K under 101.1 kPa by dynamic laser method. As the temperature increased, the solubility of SI-VI in four binary mixed solvents all increased. Meanwhile, with the rising of water content in solvent mixture, the solubility of SI-VI reduced in methanol + water and ethanol + water system, as well as increased and reached the peak before decreased in acetonitrile + water and n-propanol + water system. The experimental solubility data was correlated with NRTL model, Wilson model, Van't Hoff model, and λh model. The Van't Hoff model could best describe the solubility behavior according to the results of AIC analysis, and the maximum value of RMSD was 3.632 × 10−3. The KAT-LSER model was applied to explore the solvent effect for SI-VI in pure and binary solvents. And according to the obtained Wilson model parameters, the thermodynamic properties during the dissolution of SI-VI were calculated. The results showed that the dissolution process of SI-VI in the all mixed solvents was spontaneous.