Additive estimates of the thermodynamic properties of triene hydrocarbons over a wide temperature range

An increment method for calculating the thermodynamic properties of aliphatic triene hydrocarbons is suggested. The method is based on substituting procedures and additive inclusion of 1,4-and 1,5-carbon-carbon intramolecular interactions. Parameter values for estimating the enthalpies of formation of gaseous alkatrienes at 298.15 K were found. A procedure for determining the thermodynamic properties of conjugated alkatrienes at arbitrary temperatures was developed. This procedure is based on the additive determination of the coefficients of polynomials that describe the temperature dependences of properties. The parameters for determining the isobaric heat capacities, entropies, and reduced enthalpies and Gibbs energies of conjugated triene hydrocarbons in the gas phase were found. Calculations reproduce experimental data with accuracy at the level of measurement errors. A thermodynamic analysis of the rearrangements of 2,6-dimethyloctatrienes (alloocimene isomers) was performed. The compositions of equilibrium mixtures of 14 aliphatic terpenes were determined at five gas phase temperatures from 298.15 to 1000 K.