The influence of the halogen atoms and acetyl group on vapour pressures and related properties of the p-haloacetophenones

• Vapour pressures of condensed phases of the p-haloacetophenones were measured.
• Accurate values of enthalpies and entropies of sublimation, vaporisation, and fusion were derived.
• The contribution of the acetyl group to standard molar ΔG and ΔH of sublimation was predicted.
• The influence of the halogen atoms on standard molar ΔG and ΔH of vaporisation was evaluated.

This work reports experimental vapour pressures at different temperatures of four halogenated acetophenones. The liquid phase vapour pressures of p-fluoro and p-chloro acetophenones were measured, respectively, across the temperatures ranges (255.1 to 310.2) K and (271.6 to 335.0) K, using a static method based on capacitance diaphragm manometers. This experimental technique was also used to measure the vapour pressures of both (crystalline and liquid) condensed phases of p-bromo- and p-iodoacetophenones, respectively, through the temperature intervals (295.3 to 378.4) K and (313.1 to 402.0) K. The temperatures and molar enthalpies and entropies of fusion of the four p-halogenated acetophenones were determined using differential scanning calorimetry. The standard molar enthalpies, entropies and Gibbs energies of sublimation and of vaporisation, at selected reference temperatures, were derived from the experimental results. The contributions of the acetyl group and of the constituent halogen atoms to these thermodynamic properties were also predicted through correlation equations.

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