Abstract

From the kinetic investigation of the cleavage of the 4-acetoxybenzoate anion (4-ABA) in the presence of three cyclodextrins (Ì-CD, Ý-CD, and Þ-CD) in basic aqueous solution, the results indicate that 4-ABA binds to Ì-CD fairly weakly while no binding is observed between 4-ABA and Ý-CD or Þ-CD. The effects of the three CDs on the kinetics of the aminolysis of 4-ABA by primary amines have been investigated. Rate constants for the nucleophilic attack by free and CD-bound amine are obtained. For Ì-CD, values of the reactivity ratios for the linear amines are low (<1) implying deceleration of the aminolysis reaction due to binding to the CD. In the case of Ý-CD, the reactivity ratios are slightly larger (>1 for both n -alkyl and branched amines), implying modest catalysis. As for Þ-CD, the values of the reactivity ratios are >2, which also signifies modest catalysis