Determination of vaporization enthalpies of simple organic molecules by correlations of changes in gas chromatographic net retention times

Abstract

A technique is described for determining vaporization enthalpies Δg1Hm(298 K) of organic compounds by high resolution gas chromatography. The technique correlates changes in net retention times of compounds whose Δg1Hm(298 K) are known with those of the compound(s) of interest. The best results are obtained when the reference compounds are structurally similar and in the same chemical family. Application to hydrocarbons and various hydrocarbon derivatives containing one functional group is documented in this report. Comparison with literature values of 102 compounds resulted in a standard deviation of 1.27 kJ mol−1. In most cases, the difference between the literature value and the value from our results is within the normal errors associated with vaporization enthalpy determinations. A linear correlation between the logarithms of experimental vapor pressure and reciprocal retention time was also observed for the compounds studied.