Excess molar enthalpies of the ternary systems (acetonitrile plus methyl isobutyrate plus toluene) and (propionitrile plus methyl isobutyrate plus ethylbenzene) at 298.15 K

Excess molar enthalpies were measured at 298.15 K with a flow calorimeter b uilt in our laboratory for the two ternary systems (acetonitrile+methyl iso butyrate+toluene) and (propionitrile+methyl isobutyrate+ethylbenzene). Expe rimental data were nicely predicted by some empirical and semiempirical pro cedures, exception made for UNIFAC group contribution method. The latter eq uation proved unsatisfactory for all mixtures containing methyl isobutyrate . The first ternary set proved a good model system to simulate mixing entha lpies reported in the literature for mixtures of poly(styrene-co-acrylonitr ile) with polymethylmethacrylate.