LAUSR

Isobaric vapor–liquid equilibrium (VLE) data were measured for two binary systems comprising n-heptane with one of di-n-propyl ether (DNPE) or butyl ethyl ether (BEE) at 60 kPa. Slight positive deviations from ideality were apparent in both systems, but not so strong as to result in azeotropic behavior. The data for both systems were shown to be thermodynamically consistent using both the Wisniak L/W and McDermott-Ellis consistency tests. Data were further well correlated by the nonrandom two-liquid (NRTL) activity coefficient model and fairly predicted using the Dortmund-modified UNIFAC model. The data presented serve to fill the gap in the literature for data sets of structural isomers of C6 ethers with n-heptane, where data for the linear isomers are absent. This data, combined with that available for the branched isomers, serve to highlight the role of polar functional group location on associated mixture behavior in such systems.