ISSN:
1573-904X
Keywords:
catalysis
;
zinc ion
;
hydrolysis
;
aminolysis
;
cephalosporins
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract Earlier studies of the hydrolysis and aminolysis of penicillin, in the presence of zinc ion and tromethamine (Tris), revealed a very rapid catalysis mediated by a ternary complex in which the metal ion brought the reactants into close proximity in a suitable configuration for reaction. In the present work similar studies with a group of cephalosporins show not only much slower rates of reaction but a different mechanism in which the zinc ion–tromethamine complex functions as a nucleophile in a bimolecular reaction. Evidence for the differences in mechanism includes not only the different dependence of rate upon tromethamine concentration, but comparable rates of reaction of methyl esters of a penicillin and a cephalosporin and the reaction products observed by high-performance liquid chromatography.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1016404111054
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