Prediction of vapor pressures, boiling points and enthalpies of fusion for twenty-nine halogenated dibenzo-p-dioxins

Abstract

A vapor pressure correlation method was used to predict vapor pressures for 15 polychloro-, 8 polybromo-, 2-iodo-, 2,3-difluoro- and 4 mixed halogenated dibenzo-p-dioxins. Experimental vapor pressures, obtained on 10 chlori nated dibenzo-p-dioxins, were used as data base for the predictions. The correlation method uses the liquids as reference states. Boiling points and enthalpies of fusion were deduced for the measured compounds and were correlated with the degree of halogenation. The calculated boiling points and enthalpies of fusion are in good agreement with observed values. The two correlations were used to predict boiling points and enthalpies of fusion for related dioxins of known melting points, and these values served as starting point for the vapor pressure predictions. Molar heat capacities of the gaseous and the liquid phases, enthalpies and entropies of evaporation, of sublimation and of fusion were also estimated for the investigated halogenated dibenzo-p-dioxins.