The vaporization enthalpy and vapor pressures of liquid adamantane, diamantane and α- and β-cedrene by correlation gas chromatography

Abstract

This work examines the use of two different sets of standards to evaluate vaporization enthalpies and liquid vapor pressures of a series of polycyclic hydrocarbons that include adamantane, diamantane, and α and β-cedrene by correlation gas chromatography. Several n-alkanes and a series of cyclic and polycyclic hydrocarbons were selected as standards to independently evaluate the appropriateness of using n-alkanes to evaluate these properties in two branched polycyclic sesquiterpenes. Vapor pressures of two of the polycyclic hydrocarbons examined, 1,3-dimethyladamantane and 1,4-di-t-butylbenzene, are known and the results obtained using n-alkanes as standards were used for comparisons. Standards for evaluation of adamantane and diamantane included these two compounds along with α-pinene, and camphene; a series of n-alkanes were also used in separate experiments for evaluation of the adamantanoids. The n-alkane standards included decane and dodecane through to pentadecane. Vapor pressures for adamantane and diamantane evaluated in this work were combined with literature values for 1,3-dimethyladamantane and 1,4-di-t-butylbenzene at elevated temperatures to also evaluate liquid vapor pressures and vaporization enthalpies for α- and β-cedrene. The results were compared to those evaluated independently using n-alkanes. The results of the experiments are discussed.