Thermodynamics of mixtures containing ethers. Part I. DISQUAC characterization of systems of MTBE, TAME or ETBE with n-alkanes, cyclohexane, benzene,alkan-1-ols or alkan-2-ols. Comparison with Dortmund UNIFAC results

Binary mixtures of methyl tert-butyl ether (MTBE), tert-amyl methyl ether ( TAME) or ethyl tert-butyl ether (ETBE) and n-alkanes, cyclohexane, benzene, alkan-1-ols or alkan-2-ols are characterized in terms of DISQUAC. The corr esponding interaction parameters are reported. Systems with isomeric monoox aalkanes (linear or branched) and n-alkanes are characterized by the same Q UASICHEMICAL (QUAC) interaction parameters. The DISPERSIVE (DIS) parameters are larger for those mixtures with tertiary-alkyl ethers. It is remarkable that in systems with alkan-1-ols, the first and third QUAC parameters are kept constant. The same trend is observed in many other alcoholic solutions previously studied. Mixtures with alkan-1-ols or alkan-2-ols differ only i n the DIS parameters, which are larger for those systems with alkan-2-ols. Vapour-liquid equilibria (VLE), molar excess enthalpies (H-E), logarithms o f activity coefficients at infinite dilution (ln gamma(i)(infinity)) or sol id-liquid equilibria (SLE) are correctly described by DISQUAC. H-E values o f ternary systems, including compounds considered in this work, are also re presented by DISQUAC using binary parameters only. A complete comparison be tween DISQUAC calculations and those obtained from the Dortmund version of UNIFAC using the parameters available in the literature is included. DISQUA C improves results, except for VLE of mixtures including n-alkanes, which a re slightly better represented by UNIFAC. This may be attributed to the fac t that the empirical combinatorial term used in UNIFAC is more suitable, pa rticularly for those systems with components very different in size. DISQUA C also improves results obtained from the ERAS model for H-E of alcoholic s olutions (where association is expected). Thermodynamic properties are anal ysed in terms of the effective dipole moments ((u) over bar). The importanc e of structural effects is remarked.