Mechanistic aspects of oxidation on L-tyrosine by diperiodatocuprate(III) complex in alkali media: a kinetic model

Abstract

Abstract:Oxidation of an amino acid, L-tyrosine (L-Tyr) by diperiodatocuprate(III) (DPC) in alkaline medium at a constant ionic strength of 0.1 mol dm -3 was studied spectrophotometrically at different temperatures (288.1 -313.1 K). The reaction between DPC and L-Tyr in alkaline medium exhibits 1:4 stoichiometry (L-Tyr:DPC). Intervention of free radicals was observed in the reaction. Based on the observed orders and experimental evidence, a mechanism involving monoperiodatocuprate(III) (MPC) as the reactive oxidant species has been proposed. A suitable mechanism is proposed through the formation of a complex and free radical intermediate. The products were identified by spot test and characterized by spectral studies. The reaction constants involved in the different steps of the mechanism were calculated. The activation parameters with respect to slow step of the mechanism were computed and are discussed. The thermodynamic quantities were determined for different equilibrium steps. Isokinetic temperature was also calculated and found to be 252.3 K. Warsaw and Springer-Verlag Berlin Heidelberg. © Versita

Fabrication of novel electrochemical sensors based on modification with different polymorphs of MnO2nanoparticles. Application to furosemide analysis in pharmaceutical and urine samples

“…The obtained LOD is very sensitive if compared with the values obtained by other reported methods (Table 5). [53][54][55][56][57][58][59] This wide linear range and low detection limit can be attributed to the effect of the g-MnO 2 /chitosan-modied PGE, which provides a large surface area and high electrical conductivity with FUR. The precision of the proposed sensor was evaluated (using 2.0 mmol L À1 FUR) on the same day (intra-day) and on 5 successive days (inter-day).…”

“…[49][50][51][52] If compared with other reported methods, electrochemical methods have several advantages such as simplicity, low operational cost, high sensitivity and short analysis time. There are few electrochemical methods that were reported for the determination of FUR; [53][54][55][56][57][58][59] however, all of them lack the simplicity and selectivity to the negatively charged FUR.…”

Synthesis, structural characterization and electrochemical studies of nickel(II), copper(II) and cobalt(III) complexes of some ONS donor ligands derived from thiosemicarbazide and S-alkyl/aryl dithiocarbazates

“…It is well known that coordination of metals to Schiff base ligands may enhance their biological activities [2,3]. Many new Schiff bases and their metal complexes reported in the literature have been studied electrochemically, using various electrodes and solvents, with a view to understand the mechanism of their biological activities [4][5][6]. Tridentate Schiff bases with N, O and S donor atoms are of special interest because of their ability to form stable transition metal complexes with interesting physico-chemical properties.…”

Electrochemical investigations of some newly synthesized arylazapyrazole derivatives

“…This may be attributed to the preceding adsorption of the analyte onto the electrode surface with sufficient negative enthalpy which surmounts the positive enthalpy of the rate determining redox step of the electrochemical reaction [16,17]. Before undergoing electrochemical reduction, compound solvated in liquid medium and get adsorbed on the electrode surface (Eqs.…”