Abstract
13C NMR chemical shifts of sixteen organic bases, hydrogen-bonded with trifluoroacetic acid in deuteriochloroform, are used to calculate equilibrium constants for self-association of acid and for hydrogen bonding of base with various acid n-mers. In this treatment each hydrogen bond of the species in equilibrium is assigned a free energy. The equilibrium constants then correspond to changes in these energies. Thermodynamic models are proposed which differ in the extent to which a given hydrogen bond perturbs the free energies of neighboring bonds in the molecular aggregates. Each furnishes a minimum set of independent, freely variable equilibrium constants, the values of which are then determined through a least squares fitting of the experimental data by an iterative procedure.
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Davis, J.P., Schuster, I.I. Hydrogen bonding of organic bases with trifluoroacetic acid in chloroform: A method of calculating association constants of multi-equilibria systems. J Solution Chem 13, 167–178 (1984). https://doi.org/10.1007/BF00645875
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DOI: https://doi.org/10.1007/BF00645875