Kinetics and Mechanism of Oxidative Transformations of (6R)-6-( -Phenyl-D-glycylamino)penicillanic Acid (Ampicillin) by Manganese(III) in Pyrophosphate Medium

Manganese(III) has been stabilized in weakly acidic solution by pyrophosphate and the complex formed was elucidated spectrophotometrically. Stoichiometry of manganese(III) oxidation of ampicillin in pyrophosphate medium was established in the pH range 2.0–3.0 by iodometric and spectrophotometric methods. The oxidation follows frst order kinetics in [Mn(III)]. The effect of varying [Mn(III)], [Amp], [H], added [Mn(II)], total [ ] P O 2 7 4 and added[ ] ClO 4 , [ ] SO 4 2 ions have been studied. The order in [Amp] is unity and increase in [H] increases the rate. With increase in [Mn(II)] and[ ] P O 2 7 4 , a retardation effect was noticed. Oxidation products have been proposed. Dependence of reaction rate on temperature has been studied and activation parameters were computed. A mechanism consistent with the observed results has been proposed.