(Vapour + liquid) equilibria and excess molar enthalpies for mixtures with strong complex formation. Trichloromethane or 1-bromo-1-chloro-2,2,2-trifluoroethane (halothane) with tetrahydropyran or piperidine

Isothermal (vapour + liquid) equilibria were measured for (trichloromethane + tetrahydropyran or piperidine) at T= 333.15 K and {1-bromo-1-chloro-2,2,2-trifluoroethane (halothane) + tetrahydropyran or piperidine} atT= 323.15 K with a circulation still. The results were verified by effective statistical procedures and used to calculate activity coefficients and excess molar Gibbs free energiesGmE . Excess molar enthalpiesHmE for these mixtures were determined at T= 298.15 K by means of an isothermal CSC microcalorimeter equipped with recently reconstructed flow mixing cells. Reliable performance of the calorimetric setup was proved by the good agreement of HmEfor (hexane + cyclohexane), (2-propanone + water), and (methanol + water), with the best literature results. The trichloromethane- or halothane-containing mixtures exhibit strong negative deviations from Raoult’s law and are highly exothermic, thus indicating that complex formation via hydrogen bonding is a governing nonideality effect. A close similarity in the behaviour of corresponding mixtures with trichloromethane and halothane is observed, but for halothane-containing mixtures,GmE and HmEare consistently more negative, confirming that halothane is a more powerful proton donor than chloroform.