A THERMODYNAMIC STUDY OF THE REACTIONS OF CYCLODEXTRINS WITH PRIMARY AND SECONDARY ALIPHATIC-ALCOHOLS, WITH D-PHENYLALANINE AND L-PHENYLALANINE, AND WITH L-PHENYLALANINEAMIDE

Equilibrium constants and standard molar enthalpies of reaction have been determined by titration calorimetry for the reactions of 1-propanol, 2-propanol, 1-butanol, (R)-(+)-2-butanol, (S)-((-))-2-butanol, (+/-)-butanol, (R)-(+)-2-pentanol, (S)-((-))-2-pentanol, (R)-(+)-2-hexanol, (S)-((-))-2-hexanol, (R)-(+)-2-heptanol, (S)-((-))-2-heptanol, D-phenylalanine, L-phenylalanine, and L-phenylalanineamide with alpha-cyclodextrin and beta-cyclodextrin. The standard molar Gibbs energies, standard molar enthalpies, and standard molar entropies for these reactions correlate well with respect to the number of carbon atoms in the chemical formula of the alcohol and form a series of distinct curves for the different types of alcohols. The results are also discussed in relation to hydrophobic, steric, and charge effects and the exchange reaction for a ligand from alpha-cyclodextrin to beta-cyclodextrin. With the exception of the results for the standard molar enthalpies of reaction of the 2-butanols with alpha-cyclodextrin, the results obtained in this study show that, within the indicated uncertainties, there are no differences in any of the thermodynamic quantities for the reactions of these ligands with either alpha- or beta-cyclodextrin due to the change in the location of a hydrogen atom on an optically active carbon atom.