Application of the ERAS model to HE and VE of 1-alkanol + 1-alkene and 1-alkanol + 1-alkyne mixtures

The extended version of the extended real associated solution (ERAS) model (Funke et al., 1989) has been used for describing experimental HE and VE data of 24 binary alkanol + alkene and alkanol + alkyne systems (Letcher et al., 1990a; Letcher et al., 1990b; Letcher et al., 1993a; Letcher et al., 1993b). HE of these systems has been obtained using flow calorimetry and VE using the vibrating tube technique. All binary combinations of methanol/ethanol/1-propanol/2-propanol + 1-hexene/1-heptene/1-octene and the corresponding combinations of alcohols with the alkyne series instead of alkenes have been studied. The ERAS model accounts for free volume effects according to the Flory-Patterson model and additionally for association effects between the molecules involved. In case of the studied mixtures the association effects arise from the chain association of the alkanol molecules and the cross association of the alkanol with acid H atoms in neighborhood of the unsaturated bondings of the hydrocarbons. The parameters adjusted to the mixture properties are two cross association parameters and the interaction parameter responsible for the exchange energy of the v.d.Waals interactions. Self-association parameters of the alkanols are taken from literature. eared that self association of alkenes and alkynes can be neglected. Furthermore, no cross association between alkanols and alkenes was necessary for describing properly HE and VE in the alkanol + alkene mixtures. However, for the alkanol + 1-alkyne systems, the corresponding cross association has to be taken into account. Reaction enthalpies and reaction volumes are found to be remarkably lower than those for the self association of alkanol molecules. sults obtained for HE and VE are in good agreement with the experiments for all 24 systems. The systematic study demonstrates the excellent ability of the ERAS model to describe simultaneously different excess properties of associated solutions.