Examination of the inert solvent assumption in the ideal associated solution model. Enthalpy of chloroform–triethylamine complex dissociation

Abstract

We have made new measurements of the enthalpies of adding cyclohexane to mixtures of chloroform + triethylamine + cyclohexane at 25 °C. The results of these measurements have been analysed in terms of the ideal associated solution model to obtain ΔHθ for the dissociation of the chloroform-triethylamine complex. Our value of ΔHθ is in excellent agreement with a published value that was obtained from results of measurements on binary mixtures of chloroform + triethylamine. This agreement indicates that it is usefully accurate to treat mixtures of chloroform + triethylamine + cyclohexane as ideal mixtures of chloroform, triethylamine, cyclohexane, and chloroform-triethylamine complex. This result has important implications for studies of associated systems dissolved in "inert" solvents and helps to provide a connection between complex formation in dilute solutions and in binary systems (A + B, no solvent). Keywords: ideal associated solution model, chloroform, triethylamine, inert solvent, hydrogen bonded complex.