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

Research paper by V. Raj, T. Chandrakala, K. Rajasekaran

Indexed on: 23 Jul '08Published on: 23 Jul '08Published in: Journal of Chemical Sciences



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-consdtants and Hansch hydrophobicity parameters π. At higher concentrations of CD, there is an additional catalysis due to the formation of weak 1G:2H complex.