A Thermodynamic Study of the Reactions of Cyclodextrins with Primary and Secondary Aliphatic Alcohols, with D- and L-Phenylalanine, and with L-Phenylalanineamide

Article abstract of DOI:10.1021/j100091a051

Equilibrium constants and standard molar enthalphies 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 α-cyclodextrin and β-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 α-cyclodextrin to β-cyclodextrin.With the exception of the results for the standard molar ethalpies of reaction of the 2-butanols with α-cyclodextrin, the results obtained in this study show that, within the indicated uncertainities, there are no differences in any of the thermodynamic quantities for the reactions of these ligand with either α- or β-cyclodextrin due to the change in the location of a hydrogen atom on an optically active carbon atom.