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 lambda h 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 x 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 ther-modynamic 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.