Normal boiling points for organic compounds: Correlation and prediction by a quantitative structure-property relationship

We recently reported a successful correlation of the normal boiling points of 298 organic compounds containing O, N, Cl, and Br with two molecular descriptors.' In the present study the applicability of these two descriptors for the prediction of boiling points for various other classes of organic compounds was investigated further by employing a diverse data set of 612 organic compounds containing C, H, N, O, S, F, Cl, Br, and I. The data set was divided into 9 subsets, and additional descriptors were sought for each subset, which, together with the gravitation index and the charged surface area of hydrogen-donor atoms, would model the boiling points. The additional descriptors were then each tested for global relevance and retained only if this was found. A final eight-parameter correlation model was thus deduced which had R-2 = 0.965 and a standard error of 15.5 K approaching the estimated average experimental error for the data set. The model appears to be general for a wide variety of organic compounds.