Calculation of the vaporization enthalpies of alkylaromatic hydrocarbons as a function of temperature from their molecular structure

Abstract

Vaporization enthalpy is one of the most important parameters for the description of vapor-liquid equilibrium in pure substances and mixtures. However, the experimental data on the vaporization enthalpy in the wide temperature range are rarely available. Here we tested the validity of a new approach for the estimation of the temperature dependence of the vaporization enthalpy of alkylaromatic compounds, which is based on a correlation between the heat capacity change on transition from a liquid to an ideal gas and vaporization enthalpy at 298.15 K. The combination of this approach and previously developed scheme for the calculation of the vaporization enthalpies of alkylarenes at 298.15 K is a way to estimate vaporization enthalpy at an arbitrary temperature from the molecular structure. 314 vaporization enthalpies of 156 alkylaromatic compounds between 240 and 650 K were calculated. The calculated magnitudes were compared with the available literature data and the values derived by widely used Chickos et al. scheme. In most cases, an agreement with the literature data was within the limits of experimental error (RMS = 1.9 kJ·mol−1). The performance of Chickos et al. scheme was comparable when the temperature range of adjustment was less than 100 K, but decreased in the wider adjustment intervals and for the larger molecules.