Thermodynamic Properties of Selected Bicyclic Terpenes and Related Substances by Gas Chromatography and Group Contributions

Terpene compounds in the lower layer of the atmosphere can contribute to environmental problems through the formation of particulate material known as secondary organic aerosol (SOA). A clear understanding of the formation and composition of these particles hinges on reliable thermodynamic data. Quick estimation of these physical properties is highly desired. While experimental methods require significant resources and time, the prediction of pure-component properties through group contributions is easily applicable and straightforward. The present study compares the experimental enthalpies of vaporization at 298.15 K for bicyclic terpenes and related substances derived from the gas chromatography technique with estimated values provided by three group contribution methods. A new group contribution model specifically designed for terpene compounds is introduced. Furthermore, this study reveals previously unreported values in the literature for the enthalpy of vaporization at 298.15 K and the normal boiling temperature of Thymol methyl ether, Fenchyl alcohol, and Bicyclo [4.1.0] heptane-7-carboxylic acid.