Solubility modeling with a nonrandom two-liquid segment activity coefficient model

Chau Chyun Chen, Yuhua Song

Research output: Contribution to journalArticlepeer-review

198 Scopus citations


A segment contribution activity coefficient model, derived from the polymer nonrandom two-liquid model, is proposed for fast, qualitative estimation of the solubilities of organic nonelectrolytes in common solvents. Conceptually, the approach suggests that one account for the liquid nonideality of mixtures of complex pharmaceutical molecules and small solvent molecules in terms of interactions between three pairwise interacting conceptual segments: hydrophobic segment, hydrophilic segment, and polar segment. In practice, these conceptual segments become the molecular descriptors used to represent the molecular surface characteristics of each solute and solvent molecule. The treatment results in component-specific molecular parameters: hydrophobicity X, polarity Y, and hydrophilicity Z. Once the molecular parameters are identified from experimental data for common solvents and solute molecules, the model offers a simple and practical thermodynamic framework to estimate solubilities and to perform other phase equilibrium calculations in support of pharmaceutical process design.

Original languageEnglish
Pages (from-to)8354-8362
Number of pages9
JournalIndustrial and Engineering Chemistry Research
Issue number26
StatePublished - Dec 22 2004


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