The dissolution behavior of 3,4-O-isopropylidene clindamycin in twelve mono-solvents: Solubility, intermolecular interactions, and apparent thermodynamics

The solubility of 3, 4-O-isopropylidene clindamycin (OIC) was determined in twelve solvents at p = 101.3 kPa with the temperature from 273.15 K to 313.15 K. The solubility of OIC increases with the raise temperature. Among the selected solvents, 2-butanol showed the best dissolving ability for OIC, while acetonitrile showed the worst dissolving ability. The obtained data are neatly correlated with five models, including van't Hoff, Yaws, λh, Wilson, and nonrandom two-liquid interaction model (NRTL), with Yaws equation yielding the most accurate predicted results. Moreover, the Conductor-like Screening Model for Real solvents (COSMO-RS) provides better calculated results for the protic solvents than the aprotic ones except for acetonitrile. The dissolving mechanism of OIC was investigated with intermolecular interaction between OIC and solvents, and the analyses indicate that the dissolving process is affected by intermolecular interaction, molecular shape, and size of both solvents and the solute. The apparent thermodynamics analysis shows that the dissolving process of OIC before reaching equilibrium in the twelve solvents is spontaneous, endothermic, and enthalpy driven.