Experimental determination of thermodynamic properties of terpene and aromatic ketones by gas chromatography

The terpene and aromatic ketones are among oxygenated compounds present in essential oils (Eos). They are substances of great importance to the chemical, pharmaceutical, and the food industries. Because of their applications in these industries, it is extremely necessary to know their thermodynamic properties and to obtain reliable data of these properties. This work aims to determinate experimentally the enthalpy of vaporization ( ∆H vap ) and normal boiling temperature ( T nb ) of some terpene and aromatic ketones and other oxygenated compounds present in essential oils by the gas chromatography technique (GC). The additional goal is to evaluate three group contribution models developed to estimate enthalpies of vaporization. The experimental determination of thermodynamic data using GC involves the use of the chromatographic retention index in combination with Kirchhoff-Rankin type equations. Gas chromatography experiments were carried out within a defined temperature range consistent with the nature of the compounds studied. In all, 11 compounds were evaluated. The ∆H vap data were determined at 298.15 K. The results obtained agreed with those found in the literature, showing small relative deviations (RD), demonstrating that the CG technique can be a good tool for obtaining the thermodynamic properties studied. In addition, unpublished data of ∆H vap at 298.15 K and T nb for the compounds bicyclo[2,2,2]octan-2,5-dione, methyl-jasmonate and 4-(4-hydroxyphenyl)-2-butanone are reported. • Three group contribution models to estimate enthalpy of vaporization were evaluated. • Thermodynamic properties were determined by gas chromatography correlation. • Unpublished enthalpies of vaporization at 298.15 K are reported.