The binary mixture of water and isopropyl alcohol isopropanol or propan2ol presents a positive azeotrope at 1 atm This azeotrope is labeled in the ternary diagram and contains mole isopropanol It is possible to break this azeotrope using extractive distillation A list of entrainers includes 1 12ethanediol or ethylene glycol 2 DSMO dimethyl sulfoxide 3 methyl2pyrrolidone or NMP 4 methyl2piperidone and 5 methyl6caprolactam; see 1 In this Demonstration residue curves are computed for a ternary mixture composed of DSMO water and isopropanol It is clear that 1 the high boiling DSMO is a stable node 2 the azeotrope between water and isopropanol is an unstable node and 3 two pure components water and isopropyl alcohol are saddle points It is possible to break the azeotrope between water and isopropanol using DSMO as an entrainer since it does not introduce new azeotropes and there is only one distillation region ie there are no distillation boundaries that separate water and isopropyl alcohol You can change the vapor pressure constants the molar volumes and the Wilson model binary interaction parameters in order to check that all chemical components suggested in 1 are possible entrainers for the extractive distillation operation to separate waterisopropanol mixtures