Kinetic Evidence for Accumulation of Stoichiometrically Significant Amounts of H2I2O3 during the Reaction of I- with IO3-

B, Jesus Alberto Agreda; Field, Richard J.; Lyons, Nancy J.

doi:10.1021/jp000271w

Cited by 30 publications

(33 citation statements)

References 34 publications

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“…Our observed rate of oxidation of DMAIMSA by iodate has been determined to be secondorder with respect to acid (see Figure 5a inset), which implies that in the long run, reaction M2 is not the ratedetermining step. The second set of reactions, M5-M9, represents the standard oxyiodine reactions that have been known for a long time and whose kinetics constants are available from literature (21)(22)(23)(32)(33)(34). Reaction M5 is the well-known rate-determining step reaction for the Dushman reaction (reaction R9 in the text) (21).…”

Section: R11 With Any Oxidant) Decomposition Reaction R12mentioning

confidence: 99%

Oxidation of a Dimethylthiourea Metabolite by Iodine and Acidified Iodate: N,N‘-Dimethylaminoiminomethanesulfinic Acid ()

Otoikhian

Simoyi

Petersen

2005

Chem. Res. Toxicol.

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The two major metabolites after S-oxygenation of dimethylthiourea (dimethylaminoiminomethane sulfinic acid, DMAIMSA, and dimethylaminoiminomethane sulfonic acid, DMAIMSOA) were synthesized and tested for their reactivities in the presence of mild oxidants, aqueous iodine and acidic iodate. The stoichiometry of the iodate-DMAIMSA reaction is 2IO3- + 3NHCH3(=NCH3)CSO2H + 3H2O --> 3SO4(2-) + 2I- + 3CO(NHCH3)2 + 6H+ (A). The reaction commences with immediate formation of aqueous iodine, which is produced from the reaction between the iodide product of stoichiometry (A) and reactant iodate. The instant accumulation of aqueous iodine is due to the very slow reaction of iodine with both DMAIMSA and DMAIMSOA. In excess iodate over that required for stoichiometry (A), the stoichiometry of the reaction is 4IO3- + 5NHCH3(=NCH3)CSO2H + 3H2O --> 5SO4(2-) + 2I2 + 5CO(NHCH3)2 + 6H+ (B). Even though excess DMAIMSA solutions do not afford iodine, the initial rapid formation of iodine is still observed, which reaches a peak and then decays to conform to stoichiometry (A). The maximum transient iodine concentrations obtained are directly proportional to the acid concentrations because acid catalyzes formation of iodine and retards reactions that consume iodine. The zwitterionic forms of DMAIMSA and DMAIMSOA are very stable in acid, and DMAIMSOA, especially, is very inert and unreactive in low pH environments. The predominant pathway for the oxidation of DMAIMSOA is through an initial hydrolysis reaction to yield bisulfite and dimethylurea, while the oxidation of DMAIMSA proceeds through DMAIMSOA as well as through an early heterolytic cleavage of the C-S bond to produce a highly reducing sulfoxylate species, SO2(2-), which is later rapidly oxidized to sulfate. In aerobic conditions, the sulfoxylate species reacts with molecular oxygen to produce superoxide anion radical, which in turn will form hydrogen peroxide and hydroxyl radicals which will bring with them inadvertent genotoxicity.

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Section: R11 With Any Oxidant) Decomposition Reaction R12mentioning

confidence: 99%

Oxidation of a Dimethylthiourea Metabolite by Iodine and Acidified Iodate: N,N‘-Dimethylaminoiminomethanesulfinic Acid ()

Otoikhian

Simoyi

Petersen

2005

Chem. Res. Toxicol.

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“…HIO 2 can also disproportionate in the presence of iodide to produce more HOI: 25 HIO 2 + I -+ H + 2HOI…”

Section: Mechanismmentioning

confidence: 99%

“…Reactions R12 and R17 have been extensively studied 25 , and their kinetics parameters are known. If sequence R13 to R16 was the dominant pathway of the oxidation of NDPen, then we would expect first order kinetics in acid.…”

Section: R17mentioning

confidence: 99%

Kinetics and Mechanism of Oxidation of N-acetyl-d-penicillamine in Acidified lodate and Aqueous Iodine

Iodine¹,

Chipiso²,

Duc³

et al. 2019

S.Afr.j.chem.

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The oxidation of the biologically-active thiol, N-acetyl-d-penicillamine (NDPen) by acidified iodate and aqueous iodine has been studied. The stoichiometry of the reaction is 1:1 in which the thiol (RSH) is oxidized to its sulfonic acid (RSO 3 H) without cleavage of the C-S bond. In excess acidified iodate the reaction displayed a short induction period, followed by formation of aqueous iodine. Overall stoichiometry in excess iodate was 6:5: 6 IO 3 -+ 5 RSH + 6 H + ® 5 RSO 3 H + 3 I 2 (aq) + 3 H 2 O. The direct reaction of aqueous iodine and was relatively fast, over within 100 ms and had a stoichiometry of 1:3: 3 I 2 (aq) + RSH + 3 H 2 O ® RSO 3 H + 6 I -+ 6 H + . The reaction is essentially diffusion-controlled and our stopped-flow with a mixing time limitation of 1.00 ms could only catch the reaction of the last iodine molecule. This reaction is, however, strongly inhibited by the product of reaction, I -. This is due to the formation of the relatively inert triiodide anion: I 2 (aq) + I -® I 3 -. Mass spectrometry results showed that the reaction proceeds through the sulfinic acid with negligible stabilization of the sulfenic acid. In excess of reductant, the dimeric species is the favoured product due to a rapid condensation-type reaction between the electrophilic unstable sulfenic acid and unreacted thiol.Figure 10 Effect of varying iodide in the oxidation of NDPen. Fixed: [NDPen] = 5 ×10 -5 M, [I 2 ] = 3 ×10 -4 M, and varied [I -] = (a) 0.05 M, (b) 0.06M, (c) 0.07 M, (d) 0.08 M and (e) 0.09 M.Figure 11 ESI (+) mass spectrum of NDPen and iodate, 1:1 showing the substrate at m/z 192, oxidation products of NDPen; m/z 224 sulfinic acid of NDPen (NDPen-SO 2 H), m/z 381 is the NDPen dimer and m/z 174 iodate.

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“…basic form for mathematical modeling of the interactions between BL matrix and some analytes. 17 The possible mechanism of the UA interaction with non-oscillating DR matrix was tested on a kinetic scheme that was suggested by Agreda et al, 44 and which expressed the kinetic complexity of the Dushman reaction. 45,46 The uric acid (C 5 H 4 N 4 O 3 ) can be oxidized with HIO 3 and I 2 47,48 under acidic condition through a mechanism in which the most characteristic products are alloxan (C 4 O 4 N 2 H 2 ) and urea (CON 2 H 4 ).…”

Section: Interaction Of Ua With Both Bl Matrix and Dr Matrixmentioning

confidence: 99%

“…The rate constants for both BL and DR models reactions were taken from the literature. 32,43,44 The rate constant for additional reactions (2 and 3) are estimated in such a way that the rates of these reactions are comparable with the rates of other reactions involving iodine and hypoiodous acid; 49 the rate constant of reaction 1 is estimated through a computer simulation procedure.…”

Section: Interaction Of Ua With Both Bl Matrix and Dr Matrixmentioning

confidence: 99%

Kinetic analytical method for determination of uric acid in human urine using analyte pulse perturbation technique

Pejić

Anić

Cupić

et al. 2012

J. Braz. Chem. Soc.

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Novos métodos simples e confiáveis para a determinação de ácido úrico (UA) são propostos e validados. Para a determinação quantitativa de UA, duas matrizes foram usadas: a reação oscilatória de Bray-Liebhafsky (BL) em um estado estacionário de não equilíbrio, estável, próximo ao ponto de bifurcação (método A), e o subsistema não oscilante (mistura de KIO 3 e H 2 SO 4), isto é, reação de Dushman (RD) em um estado estacionário (método B). Os métodos propostos são otimizados num reator tanque continuamente agitado (CSTR) e aplicados com excelentes resultados na determinação de UA em amostras de urina humana. A relação linear entre o deslocamento potencial máximo DE m e o logaritmo da concentração de UA (processo A), ou entre DE m e a concentração UA (processo B) é obtido no intervalo de concentração 2,98 × 10-5-2,68 × 10-4 mol L-1 e 2,98 × 10-5-3,58 × 10-4 mol L-1 , respectivamente. Os métodos têm uma velocidade de processamento de amostra excelente de 30 amostras h-1 (método A) e 7 amostras h-1 (método B) com sensibilidade determinada para ser 1,1 × 10-5 mol L-1 (método A) e 8,9 × 10-6 mol L-1 (método B), e precisão RSD ≤ 3.4% para ambos os métodos. Alguns aspectos do possível mecanismo de ação de UA nos sistemas de reação oscilante BL e não-oscilante de Duschman, são discutidos em detalhe. Simple and reliable novel methods for the determination of uric acid (UA) are proposed and validated. For quantitative determination of UA, two matrices were used: the Bray-Liebhafsky (BL) oscillatory reaction in a stable non-equilibrium stationary state close to the bifurcation point (method A) as well as, the BL non-oscillating subsystem (mixture KIO 3 and H 2 SO 4), i.e., Dushman reaction (DR) in a steady state (method B). The proposed methods are optimized in a continuously fed well stirred tank reactor (CSTR) and applied with excellent results in the determination of UA in human urine samples. The linear relationship between maximal potential shift DE m , and both the logarithm of the UA concentration (procedure A) and UA concentration (procedure B) is obtained in the concentration range 2.98 × 10-5-2.68 × 10-4 mol L-1 and 2.98 × 10-5-3.58 × 10-4 mol L-1 , respectively. The methods have an excellent sample throughput of 30 samples h-1 (method A) and 7 samples h-1 (method B) with the sensitivity determined to be 1.1 × 10-5 mol L-1 (method A) and 8.9 × 10-6 mol L-1 (method B) as well as the precision RSD ≤ 3.4% for both methods. Some aspects of the possible mechanism of UA action on the BL oscillating and Duschman non-oscillating reaction systems are discussed in detail.

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Kinetic Evidence for Accumulation of Stoichiometrically Significant Amounts of H₂I₂O₃ during the Reaction of I^- with IO₃^-

Cited by 30 publications

References 34 publications

Oxidation of a Dimethylthiourea Metabolite by Iodine and Acidified Iodate: N,N‘-Dimethylaminoiminomethanesulfinic Acid ()

Oxidation of a Dimethylthiourea Metabolite by Iodine and Acidified Iodate: N,N‘-Dimethylaminoiminomethanesulfinic Acid ()

Kinetics and Mechanism of Oxidation of N-acetyl-d-penicillamine in Acidified lodate and Aqueous Iodine

Kinetic analytical method for determination of uric acid in human urine using analyte pulse perturbation technique

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