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Infinite dilution activity coefficients from ab initio solvation calculations
Author(s) -
Lin ShiangTai,
Sandler Stanley I.
Publication year - 1999
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.690451217
Subject(s) - unifac , activity coefficient , solvation , chemistry , dilution , partition coefficient , octanol , group contribution method , thermodynamics , acetonitrile , solvent , hexane , chromatography , organic chemistry , aqueous solution , phase equilibrium , phase (matter) , physics
A Group Contribution Solvation (GCS) model was developed to calculate infinite dilution activity coefficients (γ ∞ ) based on modern computational chemistry. The GCS model results in an average error of 7% in γ ∞ for the limited number of data points among water, n‐hexane, acetonitrile and n‐octanol, whereas the errors are 47% and 52% with the UNIFAC model and the modified UNIFAC model, respectively. GCS was also used to calculate infinite dilution partition coefficients, which can be used to determine how a dilute solute partitions between two solvents. Solutes were examined in three different liquid‐liquid systems: water/n‐hexane, water/acetonitrile, and water/n‐octanol. With GCS, the average errors are 22% (for 18 solutes), 18% (for 14 solutes) and 14% (for 15 solutes) for these solvent systems, while comparable errors are 237%, 286% and 226% with UNIFAC; and 342%, 414% and 306% with modified UNIFAC. The GCS model is a powerful new tool to predict the octanol‐water partition coefficients.