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Catalytic and inhibitory effects of β‐cyclodextrin on the hydrolysis of benzoic anhydride
Author(s) -
Brandão Tiago A. S.,
Magro Jacir Dal,
Chiaradia Louise D.,
Nascimento Maria da Graça,
Nome Faruk,
Tato Jose V.,
Yunes Rosendo A.
Publication year - 2004
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.737
Subject(s) - chemistry , hydrolysis , catalysis , aqueous solution , reaction rate constant , hydroxide , nucleophile , medicinal chemistry , ionic strength , cyclodextrin , benzoic acid , reaction rate , inorganic chemistry , organic chemistry , kinetics , physics , quantum mechanics
The hydrolysis of benzoic anhydride (Bz 2 O) in the presence of β‐cyclodextrin (β‐CD) was studied in aqueous solution as a function of pH, temperature and ionic strength, at 25°C. The experimental rate constant versus pH profiles show that, in the region of spontaneous water reaction (pH 3.0–6.5), β‐CD inhibits the reaction and the isotope effect $(k_{{\rm H_2 O}} / k_{{\rm D_2 O}} = 4.7)$ indicates that the rate determining step of the reaction corresponds to the water‐catalyzed nucleophilic attack of water on the carbonyl group of Bz 2 O. Conversely, whereas inhibition is observed at pH 6.0, catalysis of the hydroxide ion reaction is observed at pH 8.0 and it is found that the activation entropy is responsible for the catalytic phenomena in the basic hydrolysis of benzoic anhydride. Copyright © 2004 John Wiley & Sons, Ltd.