The kinetics of oxidation of chloramphenicol (CHP) by diperiodatocuprate(III) (DPC) in aqueous alkaline medium at a constant ionic strength of 0.10 mol dm-3 was studied spectrophotometrically. The reaction between DPC and CHP in alkaline medium exhibits 1:2 stoichiometry (CHP: DPC). The main oxidation products were identified by spot test, IR, NMR and GCMS spectral studies. The reaction is of first order in DPC and CHP concentrations. As the alkali concentration increases the rate of reaction increases with fractional order dependence on alkali concentration. Increase in periodate concentration decreases the rate. A suitable mechanism is proposed. The reaction constants involved in the different steps of the mechanism were calculated. The activation parameters with respect to slow step of the mechanism are computed and discussed. Thermodynamic quantities are also determined.

The kinetics of ruthenium(III) catalyzed oxidation of chloramphenicol (CHP) by diperiodatocu prate(III) (DPC) in aqueous alkaline medium at a constant ionic strength of 0.1 mol l -1 was studied spectro photometrically. The reaction between DPC and CHP in alkaline medium exhibits 1 : 2 stoichiometry (CHP : DPC). The main oxidation products were identified by spot test, IR, NMR, and GC MS spectral studies. The reaction is first order with respect to ruthenium(III) and DPC concentrations. The order with respect to chloramphenicol concentration varies from first order to zero order as the chloramphenicol con centration increases. As the alkali concentration increases the reaction rate increases with fractional order dependence on alkali concentration. Increase in periodate concentration decreases the rate. A mechanism adequately describing the observed regularities is proposed. The reaction constants involved in the different steps of the mechanism were calculated. The activation parameters with respect to limiting step of the mech anism are computed and discussed. Thermodynamic quantities are determined.

The reaction kinetics for the oxidation of theophylline by permanganate ions have been investigated in perchloric acid medium using spectrophotometric techniques at 25 • C, and at constant ionic strength 1.60 mol·dm −3 , under pseudo first order conditions. An autocatalyzed reaction is observed due to one of the products formed is Mn(II). The orders with respect to theophylline and Mn(VII) were both found to be unity, whereas fractional order is observed with respect to the autocatalyst, Mn(II). The rate of the reaction increases as the concentration of acid increases, but the order with respect to acid concentration is less than unity. The influence of temperature on the rate of reaction was studied. Based on the experimental results a suitable mechanism is proposed. The activation and thermodynamic parameters were determined with respect to slow reaction step.

The oxidation of clopidogrel hydrogen sulfate, commercially known as Plavix, by permanganate ion in aqueous perchloric acid medium at a constant ionic strength (I = 0.06 mol dm À3 ) has been investigated spectrophotometrically at 526 nm. The reaction between clopidogrel hydrogen sulfate and permanganate in acid medium exhibits a 5:4 stoichiometry. The identified oxidation products, 4,5,6,7-tetrahydrothieno[3,2-c]pyridine, (2-chlorophenyl)oxoacetic acid, and formaldehyde as a byproduct, are different from those obtained by biological metabolism. The reaction is first-order in MnO 4À and less than first-order in both the clopidogrel hydrogen sulfate and H + ion concentrations. The active species of permanganate was found to be HMnO 4 . The oxidation reaction in acid medium was found to proceed through a permanganateÀclopidogrel complex that decomposes slowly in a rate-determining step followed by other fast steps to give the products. The main products were identified by spot test and IR and GC-MS spectral studies. The reaction constants involved in different steps of the mechanism were calculated at different temperatures. The activation parameters with respect to the slow step of the mechanism were computed, and thermodynamic quantities were also determined.

The oxidation of D-mannitol by cerium(IV) has been studied spectrophotometrically in aqueous sulfuric acid medium at 25 • C at constant ionic strength of 1.60 mol dm −3 . A microamount of ruthenium(III) (10 −6 mol dm −3 ) is sufficient to enhance the slow reaction between D-mannitol and cerium(IV). The oxidation products were identified by spot test, IR and GC-MS spectra. The stoichiometry is 1:4, i.e., [D-mannitol]: [Ce(IV)] = 1:4. The reaction is first order in both cerium(IV) and ruthenium(III) concentrations. The order with respect to D-mannitol concentration varies from first order to zero order as the D-mannitol concentration increases. Increase in the sulfuric acid concentration decreases the reaction rate. The added sulfate and bisulfate decreases the rate of reaction. The active species of oxidant and catalyst are Ce(SO 4 ) 2 and [Ru(H 2 O) 6 ] 3+ , respectively. A possible mechanism is proposed. The activation parameters are determined with respect to a slow step and reaction constants involved have been determined.