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The Degradation Mechanism of an Oral Cephalosporin: Cefaclor

✍ Scribed by Bartolomê Vilanova; Josefa Donoso; Francisco Muñoz; Francisco García-Blanco

Publisher
John Wiley and Sons
Year
1996
Tongue
German
Weight
521 KB
Volume
79
Category
Article
ISSN
0018-019X

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✦ Synopsis

Abstract

The degradation of cefaclor (1), an oral cephalosporin antibiotic, was studied at 37° in a neutral aqueous medium by HPLC and ^1^H‐NMR. Under these conditions, 1 underwent intramolecular aminolysis by the 7‐side‐chain NH~2~ group on the β‐lactam moiety to give a piperazine‐2,5‐dione. The most prominent peak in the HPLC profile of a degradation solution from 1 was isolated by prep. HPLC. Mechanistically, the formation of this degradation product cis‐11 from 1 involves the contraction from a six‐membered cephem ring to a five‐membered ring, which presumably takes place via a common episulfonium ion intermediate 9 (see Scheme). Loss of the Cl‐atom from 3‐chloro‐3‐cephem is a general reaction subsequent to β‐lactam ring opening.

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Degradation kinetics and mechanisms of a new cephalosporin, cefixime, in aqueous solution
✍ Yoshihiro Namiki; Toyoshige Tanabe; Toshimitsu Kobayashi; Junko Tanabe; Yoshiko 📂 Article 📅 1987 🏛 John Wiley and Sons 🌐 English ⚖ 703 KB

Hydrolysis of cefixime in buffer solutions (pH 1-9) at 25 "C and a constant ionic strength of 0.3 was investigated using ion-pair reversed-phase HPLC. Hydrolysis rates followed pseudo first-order kinetics; the rate of hydrolysis of cefixime was very slow at pH 4-7, slightly faster at lower pH, and q