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Pd(II) catalyzed oxidation of paracetamol (PA) by sodium N-chloro p-toluenesulfonamide (chloramine-T or CAT) was studied in HClO4and NaOH solutions at 303 K. The stoichiometry and the oxidation product in both solutions were found to be the same. The determined stoichiometric ratio was 1:2 ([PA]:[CAT]) and quinone oxime was identified as the oxidized product of PA. However, the kinetics patterns in both media were different. In the acidic medium, the rate law was −d[CAT]/dt= k[CAT][PA]0.9[Pd(II)]0.8[H]−0.4and the rate law was −d[CAT]/dt= k[CAT][PA]0.9[Pd(II)] [PTS]−0.4[NaOH]−1in the alkaline medium. p-Toluenesulphonamide (PTS) is the reduced product of CAT. The kinetics of the reaction was studied as a function of temperature, ionic strength, concentration of the salt, concentration of the added reaction product, and dielectric constant of the medium to learn the mechanistic aspects of the reaction. A plausible mechanism is proposed, which is consistent with the kinetics, stoichiometry, and product of the reaction. [ABSTRACT FROM AUTHOR]

The mechanistic study of Ir(III) chloride catalyzed oxidation of Val has been studied by by N-bromophthalimide (NBP) in aqueous perchloric acid medium at 303 K. The reaction followed first order kinetics with respect to [NBP] and zero order kinetics with respect to [Val]. At lower concentration range of Ir(III) chloride, the reaction followed first order kinetics while tending to zero order at its higher concentration. A negative effect was observed for [H+] and [NHP] (phthalimide) whereas variation in [Hg(OAc)2] (mercuric acetate), [Cl-], ionic strength (I) and dielectric constant of the medium did not bring about any significant change on the rate of reaction. The rate constants observed at five different temperatures (298 K-318 K) were used to calculate the activation parameters. A plausible mechanism from the results of kinetic studies, reaction stoichiometry and product analysis has been proposed. [ABSTRACT FROM AUTHOR]

Abstract: The mechanistic study of iridium (III)-catalyzed oxidation of paracetamol has been studied by sodium N-chloro-p-toluenesulfonamide (chloramine-T) in aqueous perchloric acid medium at 308K. The reaction followed first-order kinetics with respect to [chloramine-T], [paracetamol] and [Cl−] in their lower concentrations range, tending to zero-order at their higher concentrations. First-order kinetics with respect to [Ir(III)] was observed for the oxidation of paracetamol. The rate of reaction decreased with increasing [H+] and [p-toluene sulphonamide, PTS] were observed for the oxidation of paracetamol. The variation of the ionic strength of the medium had no significant effect on the rate of the reaction. The first-order rate constant increased with decrease in the dielectric constant of the medium. The values of rate constants observed at five different temperatures were utilized to calculate the activation parameters. The reaction between chloramine-T and paracetamol in acid medium exhibits 1:2 stoichiometry. A plausible mechanism from the results of kinetic studies, reaction stoichiometry and product analysis has been proposed. [Copyright &y& Elsevier]