(Liquid + liquid) equilibrium in binary systems of isomeric C8 aliphatic monoethers with acetonitrile and its interpretation by the COSMO-SAC model

Excess Enthalpies in Binary Systems of Isomeric C8 Aliphatic Monoethers with Acetonitrile and Their Description by the COSMO-SAC Model

“…The outstanding properties of the above-mentioned systems were confirmed previously through the determination of the liquid−liquid equilibria in binary mixtures containing C 8 aliphatic ether and acetonitrile or nitromethane. 1,2 The lowest deviations from ideality were observed for the highly unsymmetrical ethers while the highest ones for the system with butyl isobutyl ether. It is interesting to note that an influence of the position isomerism on the excess enthalpy is more profound for lower amounts of acetonitrile in the mixture.…”

“…All the measured excess enthalpies were predicted by means of the COSMO-SAC model in the form described by Hsieh et al 6 The σ-profiles for the compounds had been calculated and the details are given in our previous paper. 2 Also the determined x 1 σ-profiles can be found therein. The results at 298.15 K are shown in Figure 2.…”

“…As the model for all the systems overestimate deviations from ideality, it predicts an existence of miscibility gaps that actually appear but at temperatures of about (10−50) K lower. 2 Therefore, the prediction can be recognized as qualitative only. The model predicts excess enthalpy for the system with butyl isobutyl ether considerably higher than for the remaining systems.…”

“…The predicted upper critical solution temperatures are about 60 K higher than experimental values, which means that the model exaggerates positive deviations from ideality. 2 As this observation concerns only one property (liquid−liquid equilibrium), we decided to examine excess enthalpies for the same systems. In the literature, such data have not been reported and only excess enthalpies for the dibutyl ether + acetonitrile system at 298.15 K were measured.…”

“…This paper is a continuation of our study in which an influence of position isomerism on the thermodynamic properties has been examined. , Its aim mainly concerns checking if a thermodynamic model is able to distinguish between such isomers if some mixture properties are concerned. In light of usual group contribution methods, for example, the most widespread modified UNIFAC model, the position isomers are usually recognized as identical leading to the prediction of identical thermodynamic properties.…”