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. 1 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.