Headspace gas chromatographic measurements of limiting activity coefficients of eleven alkanes in organic solvents at 25 degrees C. 1

In the present study we report the infinite dilution activity coefficients (gamma(infinity)) of 11 alkanes in 67 organic liquids at 25 degrees C measu red by fully automated headspace gas chromatography. This study is part of a more comprehensive one whose main objective is to compare the predictive ability of several semitheoretical models to estimate alkane gamma(infinity ) values. To do this it is obviously necessary to collect reliable experime ntal data spanning a wide range of chemical properties. The solutes include five linear (pentane to nonane), four branched (2-methylpentane, 2,4-dimet hylpentane, 2,5-dimethylhexane, 2,3,4-trimethylpentane), and two cyclic (cy clohexane and ethylcyclohexane) alkanes. The solvents include several homol ogous series: n-alkanes, 1-alkenes, n-alcohols, 2-ketones, nitriles, acetat es, and 34 other common volatile and nonvolatile solvents. Several modifica tions introduced to the previously reported instrumentation and to the quan titation method are discussed. The data presented are the average of at lea st two independent measurements with a precision better than 5%.