Estimations of enthalpies of vaporization of pure compounds at different temperatures by a corresponding-states group-contribution method

Two new equations (CSGC-HW1 and CSGC-HW2) for estimating enthalpies of vaporization at different temperatures with a corresponding-states group-contribution method (CSGC) are proposed. Group-contribution parameters for 76 groups were obtained by correlating the experimental enthalpies of vaporization at different temperatures (a total of 1647 data points) of 405 pure compounds including various alkanes, alkenes, cyclohydrocarbons, aromatic and oxygenated hydrocarbons as well as compounds containing sulphur, nitrogen, and halogen. Accurate estimations of enthalpies of vaporization of pure compounds are given by the CSGC-HW1 equation, which requires the normal boiling point datum and the experimental enthalpy of vaporization of the compound at the boiling point, ΔvHb. If the experimental ΔvHb is not available, the CSGC-HW2 equation can be used to yield satisfactory estimates.