Thermodynamics Research Center / ThermoML | Journal of Chemical Thermodynamics

ABSTRACT

This paper reports experimental vapour pressures at different temperatures of four substituted acetophenones. Using the diaphragm manometer static method, the vapour pressures of both (crystalline and liquid) condensed phases of ortho and para acetoxyacetophenones and also of para-methoxyacetophenone were measured in the following temperatures ranges T = (313.0-398.0) K, (315.0-378.3) K and (296.2-355.7) K, respectively. This experimental technique was also used to measure the vapour pressures of the liquid phase of meta-acetoxyacetophenone through the temperature interval T = (305.1-368.5) K. The vapour pressures of the crystalline phase of meta-acetoxyacetophenone were measured using the Knudsen effusion technique over the temperature ranges, T = (297.7-307.3) K. This technique was also used for complementing the range of the vapour pressure measurements of the ortho and para acetoxyacetophenone isomers between T = (298.0-321.3) K and (298.1-309.3) K, respectively. The standard molar enthalpies, entropies and Gibbs energies of sublimation and of vaporization, at references temperatures, were derived from the experimental results. Differential scanning calorimetry was used to determine the temperatures and molar enthalpies of fusion and of the observed crystalline transitions. The contributions of the acetoxy and acetyl groups to the sublimation properties of the compounds studied were calculated.