Air-Liquid Partition Coefficient for a Diverse Set of Organic Compounds: Henry’s Law Constant in Water and Hexadecane
HILAL, S. H., S. N. Ayyampalayam, AND L. A. Carreira. Air-Liquid Partition Coefficient for a Diverse Set of Organic Compounds: Henry’s Law Constant in Water and Hexadecane. ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, 42(24):9231-9236, (2008).
The SPARC vapor pressure and activity coefficient models were coupled to estimate Henry’s Law Constant (HLC) in water and in hexadecane for a wide range of non-polar and polar solute organic compounds without modification to/or additional parameterization of the vapor pressure or activity coefficient models. The vapor pressure model describes the solute-solute intermolecular interactions in the pure liquid phase while the activity coefficient model describes the solute-solvent and solvent-solvent (in addition to the solute-solute) intermolecular interactions upon placing solute, i, in solvent, j. These intermolecular interactions are factored into dispersion, induction, H-bonding and dipole-dipole components upon moving a solute molecule from the gas to the liquid phase. These models were tested and validated on the largest experimental HLC data set to date; 1354 organic solutes, spanning a wide range of functional groups, dipolarities, and hydrogen-bonding capabilities. The RMS deviation error for the SPARC-calculated versus the experimental log HLC for 1221 compounds in water and for 562 compounds in hexadecane were 0.456 and 0.192 (log (mole/L)/(mole/L)), respectively, spanning a range of more than 13 and 20 log units in water and hexadecane, respectively.
The aim of this study was to use the coupled SPARC vapor pressure and activity coefficient models to estimate HLC for molecules with a wide range of functional groups, dipolarities, and H-bonding capabilities in non-polar and polar liquid phases (solvents) strictly from molecular structure, without modification to/or additional parameterization of any of the SPARC physical processes sub- models.
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Organization:U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF RESEARCH AND DEVELOPMENT
NATIONAL EXPOSURE RESEARCH LAB
ECOSYSTEMS RESEARCH DIVISION
PROCESSES & MODELING BRANCH