Molecular shape effects on limiting activity coefficients: normal, branched and cyclic alkanes in 1-propanol or 2-propanol

The limiting activity coefficients were determined by the inert gas stripping method or the modified Rayleigh distillation method at 308.15 K for four linear alkanes (C5C8), three branched alkanes (C6C8), and three cycloalkanes (C5C7) and in 1-propanol and 2-propanol. The data were determined with very good precision (1–2%) and indicate that isomerization and molecular shape have an important effect over γ1∞ values. Comparison against calculations using two versions of the UNIFAC model illustrates that the so-called first-order groups do not contain all the important molecular structure information. Hence, the experimental data reported here should be useful to improve models based on group contributions to describe the phase equilibria of the present mixtures.