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Alkaline hydrolysis of cephaloridine: An 1HNMR study. Temperature dependence of the rate constants

✍ Scribed by B. Vilanova; J. Donoso; F. Muñoz; F. García Blanco

Publisher
John Wiley and Sons
Year
1993
Tongue
English
Weight
545 KB
Volume
25
Category
Article
ISSN
0538-8066

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✦ Synopsis

A kinetic study on the basic hydrolysis of cephaloridine at p D = 10.5 was carried out by using the 'H-NMR technique. Epimerization a t H7, a nucleophilic attack of hydroxyl ion on the p-lactam carbonyl group followed by the release of the pyridine molecule, and isomerization of the double bond at position 3 in the dihydrothiazine ring were the major reactions observed.

Based on the results obtained, it should be emphasized that the presence of a pyridine group at 3' results in a slightly increased formation constant for the exo methylene compound relative to other cephalosporins with different substituents at that position.

The activation energy for the epimerization constant and the cleavage of the p-lactam ring a t pD 10.5 was 21.2 kcal/mol.

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