The vapour pressure (po) of an organic compound is one of the main factors controlling its equilibrium partitioning between the gas and condensed (aerosol) phases.
Here we provide three structure-based estimators for vapour pressure, courtesy of DDBST GmbH: first, that Nannoolal et al. (1) for boiling point coupled with the modified vapour pressure predictor of Moller et al. (2); second, the methods of Nannoolal et al. (1, 3) for both boiling point and vapour pressure; third, the method of Stein and Brown (4) for boiling point coupled with the the vapour pressure equation of Myrdal and Yalkowsky (5). Boiling points can alternatively be specified by the user.
The results, which include po of the liquid compound at 298.15 K, the enthalpy of vaporisation ΔHo(po) and the associated heat capacity change ΔCpo(po), can be used in E-AIM.
To estimate a vapour pressure:
(1) Y. Nannoolal, J. Rarey, D. Ramjugernath, and W. Cordes (2004) Fluid Phase Equilibria 226, 45-63.
(2) B. Moller, J. Rarey, and D. Ramjugernath (2008) J. Molecular Liquids 143, 53-63.
(3) Y. Nannoolal, J. Rarey, and D. Ramjugernath (2008) Fluid Phase Equilibria 269, 117-133.
(4) S. E. Stein, and R. L. Brown (1994) J. Chem. Inf. Comput. Sci. 34, 581-587.
(5) P. B. Myrdal and S. H. Yalkowsky (1997) Ind. Eng. Chem. Res. 36, 2494-2499.
1. The vapour pressure predictor of Moller et al. (2) is an extension of that of Nannoolal and co-workers (3), and yields more accurate results for compounds with low vapour pressures. Errors and limitations in the method of Moller et al., chiefly for molecules with large numbers of functional groups, have been rectified as described in the addendum.
2. A test dataset of 45 compounds with very low liquid vapour pressures has been provided by the group at the Centre for Atmospheric Science at the University of Manchester, and is described here. They have also evaluated and compared the vapour pressure prediction methods on this page (see M. H. Barley and G. McFiggans, Atmos. Chem. Phys. 10, 749-767, 2010).