The physical and thermodynamic properties of some associated solutions I. Dielectric constants and heats of mixing

Abstract

Abstract The dielectric constants of the liquid mixtures piperidine/tetrahydropyran, piperidine/cyclohexane, and tetrahydropyran/cyclohexane have been determined in the temperature range 20 to 60 °C. They have been used to evaluate kirkwood's g-factor for the last two systems, and for the tetrahydropyran/ cyclohexane system, dipoler contributions to the execss thermodynamic functions of mixing . which have also been calculated for the chloro form/carbon tetrachloride system. The heats of mixing of the above systems have been determined (at 20 °C) in order to compare the strengths of the various types of molecular interaction involved. All the mixtures are formed endothermally, suggesting that N — H . . .O hydrogen bonds formed in the first system are weaker than the N — H . . .N bonds solely present in the second, which has the largest excess enthalpy of the three systems. Nuclear magnetic resonance spectra have provided evidence of the formation of these hydrogen bonds.