A general structure-property relationship to predict the enthalpy of
vaporization at ambient temperatures
Öberg, T.
SAR and QSAR in Environmental Research 18, 127-139 (2007)
Abstract
The vapour pressure is the most important property of an anthropogenic
organic compound in determining its partitioning between the atmosphere and the
other environmental media. The enthalpy of vaporisation quantifies the
temperature dependence of the vapour pressure and its value around 298 K is
needed for environmental modelling. The enthalpy of vaporisation can be
determined by different experimental methods, but estimation methods are needed
to extend the current database and several approaches are available from the
literature. However, these methods have limitations, such as a need for other
experimental results as input data, a limited applicability domain, a lack of
domain definition, and a lack of predictive validation. Here we have attempted
to develop a quantitative structure-property relationship (QSPR) that has
general applicability and is thoroughly validated. Enthalpies of vaporisation at
298 K were collected from the literature for 1835 pure compounds. The
three-dimensional (3D) structures were optimised and each compound was described
by a set of computationally derived descriptors. The compounds were randomly
assigned into a calibration set and a prediction set. Partial least squares
regression (PLSR) was used to estimate a low-dimensional QSPR model with 12
latent variables. The predictive performance of this model, within the domain of
application, was estimated at n = 560, = 0.968 and s = 0.028 (log transformed
values). The QSPR model was subsequently applied to a database of 100,000+
structures, after a similar 3D optimisation and descriptor generation. Reliable
predictions can be reported for compounds within the previously defined
applicability domain.
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