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Vapor−liquid equilibrium data for the binary systems 2-methylpentane + methyl 1,1-dimethylethyl ether (MTBE), + ethyl 1,1-dimethylethyl ether (ETBE), and + methyl 1,1-dimethylpropyl ether (TAME) are reported at 101.3 kPa, including pure component vapor pressures. The measured systems, which deviate slightly from ideal behavior, can be described as symmetric regular solutions, and only the system 2-methylpentane + MTBE presents an azeotrope. Boiling points are correlated with the Wisniak−Tamir equation.

Vapor−liquid equilibrium has been measured for the binary system of methanol (1) + diethylamine (2) at 101.3 and 300 kPa. Both equilibrium isobars show strong deviations from ideal behavior and a single maximum boiling point azeotrope of practically constant composition x 1 ≈ 0.76, corresponding to a temperature of 339.8 K at 101.3 kPa and 370.0 K at 300 kPa. The trend of the high-pressure isobar data is consistent with the formation of a second minimum boiling azeotrope, confirming the multiple azeotropic behavior found by others at a higher temperature (398.58 K). Furthermore, the excess Gibbs energy is negative and inflects markedly with composition with increased pressure. The equilibrium behavior and polyazeotropy are discussed in terms of self-association and cross-association of hydroxyl and amino groups. The data were satisfactorily correlated using the Margules equation, the UNIQUAC model modified for association, and the Wisniak−Tamir equation.