Prediction of vapor pressures and enthalpies of vaporization of organic compounds from the normal boiling point temperature

Recently, our Laboratory proposed a model for the prediction of vapor pressures of organic compounds that requires only the knowledge of the normal boiling point of the compound involved, and a compound specific Kf for which generalized expressions for several classes of organic compounds as functions of the normal boiling point and the molecular weight were developed.In this work our model is compared with the one proposed in Lyman's book, which is similar to our model but uses different Kf values. The results indicate that our model provides very satisfactory results in the temperature range from the melting up to the normal boiling point and up to the critical, where no hydrogen-bonding is involved. Also, it is proven that the accuracy of our model is much better than that proposed by Lyman, especially for the high molecular weight compounds.Finally, our model is used for the prediction of enthalpies of vaporization at the normal boiling point. Excellent results are obtained that are comparable or better than those obtained with two recommended models in “The Properties of Gases and Liquids” book, where the latter, however, require as input information except from the normal boiling point the critical properties of the compound involved as well.