Kinetic and equilibrium studies associated with the formation of inclusion compounds involving n-butanol and n-pentanol in aqueous cyclodextrin solutions

Abstract

The equilibrium constants associated with the inclusion compounds of n-butanol and n-pentanol with α-cyclodextrin in aqueous solutions have been measured using the head-space analysis technique involving gas chromatography. These data confirm that a 1:1 inclusion complex is formed. The kinetics associated with the formation of these inclusion compounds have been studied using the ultrasonic relaxation method. From a detailed analysis of relaxation data it is clear that the kinetics of the process do not conform to the simple behaviour suggested by the equilibrium experiments. In addition there are also discrepancies between values of the volume change of the reaction determined independently from relaxation and density data. The significance of these results is discussed in terms of a two-step mechanism for the formation of the complex.