Oxidative Cleavage of β-Lactam Ring of Cephalosporins with Chloramine-T in Alkaline Medium: A Kinetic, Mechanistic, and Reactivity Study. (19th May 2013)

• Record Type: Journal Article
• Authors: Sukhdev, Anu; Manjunatha, A. S.; Puttaswamy, Puttaswamy
• Other Names: Anusiewicz I. Academic Editor.; Farrar J. M. Academic Editor.; Starikov E. B. Academic Editor.
• Is Part Of: ISRN physical chemistry. Volume 2013(2013)
• Publication Date: 2013-05-19
• Subjects: Chemistry, Physical and theoretical -- Periodicals; Chemistry, Physical and theoretical; 35.10 physical chemistry: general; Periodicals; Electronic journals; 541
• DOI: 10.1155/2013/738932
• Languages: English
• ISSNs: 2090-7761

Abstract

Abstract : Cephalosporins are β -lactam antibiotics, and the important drugs of this group are cephalexin, cefadroxil and cephradine. In the present research, the kinetics and mechanism of oxidation of cephalexin (CEX), cefadroxil (CFL), and cephradine (CPD) with chloramine-T (CAT) in alkaline medium were investigated at 301 K. All the three oxidation reactions follow identical kinetics with a first-order dependence each on [CAT]o and [substrate]o . The reaction is catalyzed by hydroxide ions, and the order is found to be fractional. The dielectric effect is negative. Proton inventory studies in H2 O-D2 O mixtures with CEX as a probe have been made. Activation parameters and reaction constants have been evaluated. Oxidation products were identified by mass spectral analysis. An isokinetic relation was observed with β = 378 K, indicating that enthalpy factors control the rate. The rate increases in the following order: CPD > CFL > CEX. The proposed mechanism and the derived rate law are consistent with the observed kinetics.