TY - JOUR

T1 - Prediction of vapor pressures and enthalpies of vaporization using a COSMO solvation model

AU - Lin, Shiang Tai

AU - Chang, Jaeeon

AU - Wang, Shu

AU - Goddard, William A.

AU - Sandler, Stanley I.

PY - 2004/9/9

Y1 - 2004/9/9

N2 - We have developed a general predictive method for vapor pressures and enthalpies of vaporization based on the calculation of the solvation free energy that consists of three components; the electrostatic, dispersion, and cavity formation contributions. The electrostatic contribution is determined using the quantum mechanical COSMO solvation model. Thermodynamic perturbation theory for hard-core molecules is used for the cavity term, and the dispersion term is modeled using a mean field term proportional to the density and molecular surface area. The proposed model uses one set of van der Waals atomic radii to describe molecular shape, two universal interaction parameters for the electrostatic interaction, one set of atom-specific dispersion coefficients, one universal parameter to scale the atomic exposed surface area, and a single universal parameter for the ratio of the hard-core to atomic radii. The model parameters have been determined using 371 pure substances of varying molecular structure, functionality, and size. The average accuracy of the model for vapor pressures and enthalpies of vaporization at the normal boiling temperature is found to be 76% and 4.81 kJ/mol, respectively, with temperature-independent parameters. The average error in the normal boiling temperature is found to be 16 K for species whose boiling points range from 191 to 610 K.

AB - We have developed a general predictive method for vapor pressures and enthalpies of vaporization based on the calculation of the solvation free energy that consists of three components; the electrostatic, dispersion, and cavity formation contributions. The electrostatic contribution is determined using the quantum mechanical COSMO solvation model. Thermodynamic perturbation theory for hard-core molecules is used for the cavity term, and the dispersion term is modeled using a mean field term proportional to the density and molecular surface area. The proposed model uses one set of van der Waals atomic radii to describe molecular shape, two universal interaction parameters for the electrostatic interaction, one set of atom-specific dispersion coefficients, one universal parameter to scale the atomic exposed surface area, and a single universal parameter for the ratio of the hard-core to atomic radii. The model parameters have been determined using 371 pure substances of varying molecular structure, functionality, and size. The average accuracy of the model for vapor pressures and enthalpies of vaporization at the normal boiling temperature is found to be 76% and 4.81 kJ/mol, respectively, with temperature-independent parameters. The average error in the normal boiling temperature is found to be 16 K for species whose boiling points range from 191 to 610 K.

UR - http://www.scopus.com/inward/record.url?scp=4544279720&partnerID=8YFLogxK

U2 - 10.1021/jp048813n

DO - 10.1021/jp048813n

M3 - Article

AN - SCOPUS:4544279720

SN - 1089-5639

VL - 108

SP - 7429

EP - 7439

JO - Journal of Physical Chemistry A

JF - Journal of Physical Chemistry A

IS - 36

ER -