Kinetics and mechanism of oxidation of iodide ion by the molybdenum (VI) – hydrogen peroxide system

Arias, Conchita; Mata, Fernando; Perez‐Benito, Joaquin F.

doi:10.1139/v90-230

Cited by 15 publications

(16 citation statements)

References 12 publications

(31 reference statements)

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“…The order of reaction with respect to the oxidant and the reductant was determined by implementing a series of equations (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20). The reaction was probed under the pseudo-first order-condition via keeping reductant in excess over oxidant.…”

Section: Order and Rate Constant Of The Reactionmentioning

confidence: 99%

“…The oxidation of the iodide ion and its mechanism under different experimental conditions has been of interest for years due to its applications especially in energy production and solar cells. [1][2][3][4][5][6][7][8][9] A number of studies explored the mechanism of the oxidation of the iodide ion by various transition metal complexes that can be used to enhance the efficiency of the dye-sensitized solar cells (DSSCs). The applications of transition metal complexes based upon ruthenium, cobalt, copper, nickel, and iron metals have been surfaced as sensitizers in DSSCs.…”

Section: Introductionmentioning

confidence: 99%

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Kinetics of the oxidation of iodide by dicyanobis(phenanthroline)iron(III) in a binary solvent system

Khattak

Khan

Summer

et al. 2020

Int J of Chemical Kinetics

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Oxidation of the iodide ion is an important facet of the solar cells such as perovskite solar cells and dye-sensitized solar cells. The rate of reaction undoubtedly depends upon several factors. Such parameters include reaction media, electrolyte, and the nature of solvents, and electrolyte. If these factors are optimized then the rate of the reaction can be controlled and could be used to get the maximum benefit out of it such as economically and industrially cost-effective uses of the reaction and globally environmentally benign. We studied the kinetics of the oxidation of the iodide ion in the binary solvent system that consisted of 10% (v/v) tertiary butyl alcohol and water. The transition metal complex such as dicyanobis(phenanthroline)iron(III) oxidizes the iodide ion spontaneously without any external triggering with a fast rate at 293 ± 1 K. The reaction was probed under the pseudo-first-order condition with an excess concentration of the iodide ion over dicyanobis(phenanthroline)iron(III) at 0.06 M ionic strength. The reaction was observed independent of the concentration of dicyanobis(phenanthroline)iron(III), that is, the zero order and third order with respect to the iodide ion in the selected solvent system. An overall third-order was observed for the redox reaction. The value of the multiplication product of the molar absorptivity (ɛ), path length of the cuvette (b), and overall rate constant (k) was deduced to be 1.59 × 10 6 M −3 s −1. The observed zero-order rate constant of the reaction was increased by the fractional (1.5) power of the concentration of protons in the excess concentration of acid 1 mM to 0.1 M. The multiplication product of ɛ⋅b to the fractional order rate constant (k′) was found 0.773 M −1.5 s −1 that confirms protonation of triiodide in acidic-10% (v/v) tertiary butyl alcohol-water. The effect of ionic strength showed a similar impact in different compositions of solvents such as 5, 10, and 20% (v/v) tertiary butyl alcoholwater. The observed zero-order rate constant was decreased upon increasing the ionic strength in each medium consisting of the binary solvent system.

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Section: Order and Rate Constant Of The Reactionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Kinetics of the oxidation of iodide by dicyanobis(phenanthroline)iron(III) in a binary solvent system

Khattak

Khan

Summer

et al. 2020

Int J of Chemical Kinetics

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“…18 Several oxyanions including sodium molybdate 19 will catalyse the oxidation of the iodide ion by hydrogen peroxide. Hydrogen peroxide or sodium perborate with sodium tungstate as the catalyst and potassium iodide as the source of iodine, have both been used 20 for the iodination of aromatic amides.…”

Section: Iodination Using Other Oxidantsmentioning

confidence: 99%

“…The use of hydrogen peroxide as an oxidant for the iodination of activated arenes with either iodine or potassium iodide has been used for many years. 18 Several oxyanions including sodium molybdate 19 will catalyse the oxidation of the iodide ion by hydrogen peroxide. Hydrogen peroxide or sodium perborate with sodium tungstate as the catalyst and potassium iodide as the source of iodine, have both been used 20 for the iodination of aromatic amides.…”

Section: Iodination Using Other Oxidantsmentioning

confidence: 99%

Advances in the direct iodination of aromatic compounds

Hanson

2006

Journal of Chemical Research

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“…Chloroperoxidase and bromoperoxidase 2 enzymes and model systems that mimic their activity , use a transition metal (heme-bound iron for chloroperoxidase, non-heme vanadium for bromoperoxidase) 2c to activate H 2 O 2 for the oxidation of halide to halogen or hypohalous acid. Model studies have shown that chloride, bromide, , and iodide can be oxidized by such catalysis and that the metal undergoes sequential one-electron steps. These biomimetic reactions are important to chemistry in general in that they perform many desired chemical transformations such as epoxidations and halogenations in an environmentally acceptable way.…”

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confidence: 99%

Positive Halogens from Halides and Hydrogen Peroxide with Organotellurium Catalysts

1996

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The oxidations of sodium bromide, sodium chloride, and sodium iodide to positive halogen with hydrogen peroxide in two-phase systems of dichloromethane and pH 6 phosphate buffer were catalyzed by organotellurium catalysts 1-3. The positive halogens were trapped by cyclohexene for bromine and chlorine to give mixtures of the 1,2-dihalocyclohexane (4) and 2-halocyclohexanol (5). For the bromination (4a)/hydrobromination (5a) of cyclohexene, unoptimized turnover numbers of 1010 mol of product per mole of catalyst for 1, 960 for 2, and 820 for 3 were measured with 4a/5a ratios of 55:45, 53:47, and 52:48, respectively. In cyclohexane, the turnover number for 1 was 150 and the 4a/5a ratio was 68:32. In the uncatalyzed process and in the reaction of aqueous bromine with cyclohexene, the 4a/5a ratio is 55:45 in dichloromethane and 67:33 in cyclohexane. The relative rates of catalysis for equimolar amounts of 1-3 were nearly identical to the relative second-order rate constants for oxidation of the organotellurium compounds with hydrogen peroxide, which suggests that oxidation of the catalyst is the rate-determining step of the process. Stopped-flow studies indicated a rapid reaction (k ) 22.5 ( 0.3 M -1 s -1 for iodide and 13.9 ( 0.5 M -1 s -1 for bromide) between halide and oxidized 3 to regenerate catalyst 3. Relative rates of catalysis with 0.1 mol % of 1-3 (relative to cyclohexene) were 4.6 for 1, 2.0 for 2, 1.0 for 3, and 0.11 for the control reaction with no catalyst at 296.1 ( 0.1 K. Oxidation of chloride with hydrogen peroxide with 1 as a catalyst was much slower but the unoptimized turnover number was 100 with a 4b/5b ratio of 7:93 (10:90 in the uncatalyzed process) in a two-phase cylohexane/aqueous system. Oxidized 3 reacts rapidly with both sodium chloride and sodium bromide to give products from oxidative addition of halogen to the catalyst. Stronger Te-Cl bonds relative to Te-Br bonds slow down the release of the Te(II) state of the catalyst. Positive iodine from catalysis with 1 was trapped by 4-pentenoic acid to give iodomethyl lactone 6.

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Kinetics and mechanism of oxidation of iodide ion by the molybdenum (VI) – hydrogen peroxide system

Cited by 15 publications

References 12 publications

Kinetics of the oxidation of iodide by dicyanobis(phenanthroline)iron(III) in a binary solvent system

Kinetics of the oxidation of iodide by dicyanobis(phenanthroline)iron(III) in a binary solvent system

Advances in the direct iodination of aromatic compounds

Positive Halogens from Halides and Hydrogen Peroxide with Organotellurium Catalysts

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