Spectrophotometric Investigation of Oxidation of Cefpodoxime Proxetil by Permanganate in Alkaline Medium: A Kinetic Study

Abstract

ABSTRACT.A Kinetics pathway of oxidation of Cefpodoxime Proxetil by permanganate in alkaline medium at a constant ionic strength has been studied spectrophotometrically. The reaction showed first order kinetics in permanganate ion concentration and an order less than unity in cefpodoxime acid and alkali concentrations. Increasing ionic strength of the medium increase the rate. The oxidation reaction proceeds via an alkali-permanganate species which forms a complex with cefpodoxime acid. The latter decomposes slowly, followed by a fast reaction between a free radical of cefpodoxime acid and another molecule of permanganate to give the products. Investigations of the reaction at different temperatures allowed the determination of activation parameters with respect to the slow step of proposed mechanism and fallows first order kinetics. The proposed mechanism and the derived rate laws are consistent with the observed kinetics.

Kinetics and Mechanism of Deamination and Decarboxylation of 2-Aminopentanedioic Acid by Quinolinium Dichromate (QDC) in Aqueous Perchloric Acid Medium

“…The observed modest enthalpy of activation and a higher rate constant for the slow step indicate that the oxidation presumably occurs via an inner-sphere mechanism. This conclusion is supported by observations − made earlier.…”

Anaerobic Hydrolytic Degradation of Cefpodoxime Proxetil in the Presence of UV Irradiation and in Darkness: Kinetics and pH Effect

“…However, in the basic medium (pHs 9 and 11), the peak currents of CP decrease in a similar manner to the presence of UV irradiation (Figures 5 and 6). Moreover, according to the literature 8,12 , CP is degraded to cefpodoxime, leaving >C=N-OCH 3 group "untouched", while the C=C bond is shifted in the alkaline media. Therefore, the reduction peak of C=C bond should be much more affected from that of methoxyimino group.…”

“…8,9 In the alkaline media, CP undergoes ester hydrolysis and is converted into cefpodoxime (see Scheme 1) to exhibit its antibiotic activity. 8 For the 1.0 % hydroxylamine solution, CP was degraded rapidly.…”

“…8 The degradation of CP in 0.6 mol dm −3 phosphate buffer (pH 7.4) at 37 C over 24 h was studied using HPLC and NMR techniques by Stoeckel et al 13 They reported 13 that in phosphate buffer, the major degradation product was the  2 -cephalosporin. The half-lives (t 1/2 ) for the diastereoisomers of CP were 2.5 and 2.2 h, respectively.…”