Guest-host interactions in the cleavage of phenylphenyl acetates by β-cyclodextrin in alkaline medium

Abstract

Kinetics of cleavage of phenylphenyl acetates (PPA) and several para-substituted PPAs in basic aqueous sodium carbonate-bicarbonate buffer containing β-cyclodextrin (CD) have been studied. The reaction exhibits saturation type kinetics and CD accelerates the rate of cleavage by the formation of 1G : 1H inclusion complex. The kinetic results indicate that aryloxy moiety of PPA is included in the hydrophobic cavity of CD. The overall rate constants for the cleavage of the [CD-ester] complex correlate with the Hammett σ-constants and Hansch hydrophobicity parameters π. At higher concentrations of CD, there is an additional catalysis due to the formation of weak 1G : 2H complex.