Abstract
For the molecular inclusion equilibrium between cyclohexaamylose and 1-propanol or 1-pentanol with a 1:1 inclusion complex in dilute aqueous solution: (CyD)aq+(ROH)aq _??_ (CyD·ROH)aq, the equilibrium constant K and the limiting molar ratio ymax of the alcohol included have been refined by the improved version of procedures which were proposed by the present authors [original, Nippon Kagaku Kaishi, 1983, 188; the improved version, Netsusokutei, 10, 43 (1983)]. The most probable values refined for log10K and ymax are 3.124 and 0.495 for C3H7OH, and 4.265 and 0.785 for C5H11OH, respectively.
From these results and those for cycloheptaamylose and the same alcohols reported earlier by the present authors, the enthalpies, Gibbs energies, and entropies of inclusion have been evaluated. The entropy changes are positive in all systems, showing that common “driving-force” is the increase of the entropy. The enthalpy changes are, however, exothermic for the inclusion into the rather small cavities of cyclohexaamylose, but are endothermic for the inclusion into the larger cavities of cycloheptaamylose in aqueous solutions.
