DETERMINATION OF VAPORIZATION ENTHALPIES OF SIMPLE ORGANIC-MOLECULES BY CORRELATIONS OF CHANGES IN GAS-CHROMATOGRAPHIC NET RETENTION TIMES

A technique is described for determining vaporization enthalpies Delta (1)(g)H(m)(298 K) of organic compounds by high resolution gas chromato graphy. The technique correlates changes in net retention times of com pounds whose Delta(1)(g)H(m)(298 K) are known with those of the compou nd(s) of interest. The best results are obtained when the reference co mpounds are structurally similar and in the same chemical family. Appl ication to hydrocarbons and various hydrocarbon derivatives containing one functional group is documented in this report. Comparison with li terature values of 102 compounds resulted in a standard deviation of 1 .27 kJ mol(-1). In most cases, the difference between the literature v alue and the value from our results is within the normal errors associ ated with vaporization enthalpy determinations. A linear correlation b etween the logarithms of experimental vapor pressure and reciprocal re tention time was also observed for the compounds studied.