Prediction of enthalpy and standard Gibbs energy of vaporization of haloaromatics from atomic properties

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

“…The selection of the halogenated derivatives of acetophenone for this study is also due to our interest in investigating whether enthalpies and vapour pressures of sublimation or vaporisation of halogen substituted benzenes show a regular dependence on the volume of the halogen atom as was observed previously for p-halogenated benzoic acids, methyl benzoates, and phenols [6,7]. In a recent study [9] on the estimation of thermodynamic vaporisation properties of mono and poly halogenated benzenes it was concluded that the influence of volume in poly halogenated benzenes is not additive per se but a suitable combination of volume and electron affinity enables good estimations of the vaporisation properties from the number of the constituent halogen atoms. This new method is also applicable to halogenated benzenes containing other groups beyond halogen atoms since results for the parent compound (acetophenone in the present study) are known and no significant intramolecular interactions exist between the halogen atoms and the other substituent groups.…”

“…For poly halogenated benzenes, however, a recent study [9] on the estimation of vaporisation properties of halogenated benzenes showed that a combination of volume and electron affinity of the halogen atoms [37], multiplied by their number, yielded a simple way to estimate vapour pressures and enthalpies of vaporisation, at T = 298.15 K, of halogenated benzenes, independent of the number and position of the halogen atoms. The application of this method was also successfully tested for substituted halobenzenes (benzene derivatives containing other groups beyond halogen atoms).…”

“…The application of this method was also successfully tested for substituted halobenzenes (benzene derivatives containing other groups beyond halogen atoms). The derived equations reported in that study [9] were based on the number n i of each halogen substituent i, and on the excess values of volume V XS i and of electron affinity EA XS i of each of the substituents halogen atoms. In this context, ''excess" means the atomic volume and electron affinity of the halogen atoms relatively to those of the hydrogen atom being replaced.…”

“…Our research group has been developing equations correlating thermodynamic properties of sublimation and vaporisation of organic compounds for a period of time [1][2][3][4][5][6][7][8][9]. These correlations are very useful to test the internal coherency of the experimental results and to predict results for compounds not studied experimentally.…”

“…are anchored in the results of benzene and were derived for halogenated benzenes where one or more hydrogens are replaced by halogen atoms[9]: i n i ð0:758 AE 0:010Þð10 3 V XS i =nm 3 Þ À ð1:58 AE 0:04ÞðEA XS i =eVÞ…”