APPLICATION OF THE ERAS MODEL TO H-E AND V-E OF 1-ALKANOL PLUS 1-ALKENE AND 1-ALKANOL PLUS 1-ALKYNE MIXTURES

The extended version of the extended real associated solution (ERAS) m odel (Funke et al., 1989) has been used for describing experimental H- E and V-E data of 24 binary alkanol + alkene and alkanol + alkyne syst ems (Letcher et al., 1990a; Letcher et al., 1990b; Letcher et al., 199 3a; Letcher et al., 1993b). HE Of these systems has been obtained usin g flow calorimetry and VE using the vibrating tube technique. All bina ry combinations of /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 additionall y for association effects between the molecules involved. In case of t he studied mixtures the association effects arise from the chain assoc iation of the alkanol molecules and the cross association of the alkan ol with acid H atoms in neighborhood of the unsaturated bondings of th e hydrocarbons. The parameters adjusted to the mixture properties are two cross association parameters and the interaction parameter respons ible for the exchange energy of the v.d.Waals interactions. Self-assoc iation parameters of the alkanols are taken from literature. It appear ed that self association of alkenes and alkynes can be neglected. Furt hermore, no cross association between alkanols and alkenes was necessa ry for describing properly H-E and V-E in the alkanol + alkene mixture s. However, for the alkanol + 1-alkyne systems, the corresponding cros s association has to be taken into account. Reaction enthalpies and re action volumes are found to be remarkably lower than those for the sel f association of alkanol molecules. The results obtained for H-E and V -E 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 s olutions.