Determination of Vaporization Enthalpies of Selected Linear and Branched C7, C8, C9, C11, and C12 Monoolefin Hydrocarbons from Transpiration and Correlation Gas-Chromatography Methods

Abstract

The standard molar enthalpies of vaporization of 1-methylcyclohexene, 4-methylcyclohexene, 2,4-dimethyl-2-pentene, cis-2-heptene, trans-4-octene, 1-nonene, 2,6-dimethylheptene, 1-undecene, trans-2,2,4,6,6-pentamethyl-3-heptene, and cis-2,2,4,6,6-pentamethyl-3-heptene at the temperature T = 298.15 K were obtained from the temperature dependence of the vapor pressure measured by the transpiration method. The values of (298.15 K) for these compounds and additionally for 3-methylcyclohexene were also measured using the correlation gas-chromatography method. The results from both methods are indistinguishable within the experimental uncertainties of less than ±0.5 kJ·mol-1. Results from this work together with the data available from the literature were used to derive correlations for the prediction of the standard molar enthalpies of vaporization (298.15 K) of monoolefins with linear and branched hydrocarbon chains.