Infinite dilution activity coefficients of n-alkane solutes, butane to decane, in n-alkane solvents, heptane to hexatriacontane

Abstract

The literature data for the infinite dilution activity coefficients, γ i ∞, of alkane solutes having short carbon chains in alkane solvents having long carbon chains have been investigated. The total number of the literature values is 215, covering the alkane solutes from butane to decane, alkane solvents from heptane to hexatriacontane, and temperatures from 280.15 to 373.15 K. The values of ln γ i ∞ are independent of the measuring techniques that included chromatography, gas stripping (GS) and a static equilibrium cell (SEC). The values of ln γ i ∞ obtained at different temperatures for given solute–solvent systems are the same within experimental error. The values of ln γ i ∞ are directly proportional to ( q i − q j )/ q i , where q i and q j , respectively, denote the measures of the molecular surface areas of solute i and solvent j. The range in the variation of ln γ i ∞ is extensively negative as −0.50 to 0.0, indicating molecular associations between both solute–solvent and solvent–solvent alkanes, probably forming parallel frameworks. The relationship between ln γ i ∞ and ( q i − q j )/ q i cannot be estimated by the combinatorial entropy terms from the conventional solution theories such as the ideal solution, the regular solution, and the Flory–Huggins and the UNIQUAC models.