Iridium(III) catalyzed oxidation of iodide ions in aqueous acidic medium

Abstract

Oxidation of iodide ions by K 3 Fe(CN) 6 , catalyzed by hydrogen ions obtained from hydrochloric acid was found to be further catalyzed by iridium(III) chloride. Rate, when the reaction is catalyzed only by the hydrogen ions, was separated from the rate when iridium(III) and H + ions both, catalyze the reaction. Reactions studied separately in the presence as well as in the absence of IrCl 3 under similar conditions were found to follow second order kinetics with respect to [I ) ]. While the rate showed direct proportionality with respect to [K 3 Fe(CN) 6 ] and [IrCl 3 ]. At low concentrations the reaction shows direct proportionality with respect to [H + ] which tends to become proportional to the square of hydrogen ions at higher concentrations. Strong retarding affect of externally added hexacyanoferrate(II) ions was observed in the beginning but further addition affects the rate to a little extent. Changes in [Cl ) ] and also ionic strength of the medium have no effect on the rate. With the help of the intercept of catalyst graph, the extent of the reaction, which takes place without adding iridium(III), was calculated and was found to be in accordance with the values obtained from the separately studied reactions in which only H + ions catalyze the reaction. It is proposed that iridium forms a complex, which slowly disproportionates into the rate-determining step. Thermodynamic parameters at four different temperatures were calculated.

Iridium Chemistry and Its Catalytic Applications: A Brief

“…Iridium has been reported as a versatile catalyst to catalyze various chemical reactions in both the acidic and basic medium [13,14]. Iridium and its complexes have been used as homogeneous catalyst, nano-catalyst and bio-catalyst.…”

The Catalytic Efficiency of Au3+ metal ions and Au NPs on the Oxidation of Carbonyl Compounds by in situ Generated Na2FeO4 under Microwave Irradiation for Industrial Point of View

“…From these studies, it was quite obvious that oxidation occurred mainly via direct charge transfer process without changing the coordination number of iron. In current times iodide ion oxidized by K3Fe (CN)6 using the transition metal ions as a catalyst in the basic medium [9][10][11][12]. Oxidation of sulphanilic acid by K3Fe (CN)6 ion in a basic medium in the attendance of ruthenium as a catalyst [13].…”

Hexacyanoferrate(III) oxidation of arsenic and its subsequent removal from the spent reaction mixture

“…Hexacyanoferrate(III) has long been used as an oxidant presumably due its cheap availability, less complexity involved in the estimation and its capability to act in acidic and alkaline medium both [4]. Based on the assumption that slight interaction of the electronic levels of oxidant and reductant is sufficient to permit electron transfer hexacyanoferrate(III) functions in the oxidation-reduction reactions as a simple one electron abstracting reagent and oxidation invariably occurs via a direct Recently from our laboratory oxidation of iodide ion by hexacyanoferrate(III) has been reported in the presence of Pd(II), Ru(III), and Ir(III) in the presence of various acids like hydrochloric acid, sulphuric acid and perchloric acid [5][6][7].…”