Spectroscopy of chromium(VI) species

Cieślak‐Golonka, Maria

doi:10.1016/0010-8545(91)80018-9

Cited by 77 publications

(43 citation statements)

References 118 publications

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“…In the pH range studied here, Cr(V1) exists mainly as ~r~0~~- (23). Thus the first step of the proposed mechanism may be interpreted as the formation of a monochelate with GA acting as a bidentate ligand bound to Cr(V1) through the 2-hydroxylic and carboxylic groups, as shown in eqs.…”

Section: Mechanismmentioning

confidence: 76%

Oxidation of D-gluconic acid by chromium(VI) in perchloric acid

Signorella¹,

Santoro²,

Mulero³

et al. 1994

Can. J. Chem.

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The oxidation of gluconic acid by chromium(VI) in perchloric acid has been found to follow the rate law: −d[CrVI]/dt = (k′1 + k′2[GA])[H+]2[CrVI], where k′1 = (7.1 ± 0.2) × 10−4 M−2 s−1 and k′2 = (9.4 ± 0.2) × 10−2 M−3 s−1. This rate law corresponds to the reaction leading to the formation of 2-ketogluconic acid by C—H cleavage when a 20-fold or higher excess of acid over chromium(VI) is employed. Buildup and decay of chromium(V) intermediates accompany the decay of chromium(VI). Chromium(V) rates of decay are similar or slower than those of chromium(VI), as observed by electron paramagnetic resonance (epr) and visible spectrophotometry.

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Section: Mechanismmentioning

confidence: 76%

Oxidation of D-gluconic acid by chromium(VI) in perchloric acid

Signorella¹,

Santoro²,

Mulero³

et al. 1994

Can. J. Chem.

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“…The equilibrium depends on both the concentration of chromate and the concentration of protons in the aqueous solution [16]. At a pH of 5.5 employed throughout all experiments described here, the concentration for CrO 2À 4 and Cr 2 O 2À 7 to coexist in equal concentrations is approximately 1 mM total chromate.…”

Section: Oxidation Of Topd In the Presence Of Sulfate And Chromatementioning

confidence: 99%

Chromate and Dichromate Electro-Insertion Processes into a N,N,N′,N′-Tetraoctylphenylenediamine Redox Liquid

2002

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Ion transfer processes across aqueous | organic phase boundaries are of considerable importance in biological and analytical chemistry. When driven by a potential applied to the liquid | liquid interface the ion transfer may be detected as voltammetric response. Here, a potential applied to the electrode | aqueous electrolyte | organic oil (N,N,N′,N′‐tetraoctylphenylenediamine, TOPD) triple interface is employed to drive anion transfer. Upon oxidation of TOPD deposited in the form of microdroplets onto the electrode and immersed in aqueous media, the transfer of monovalent anions (perchlorate) and divalent anions (sulfate, chromate, dichromate) occurs to maintain charge neutrality in the organic oil phase. Sulfate (0.1 M) as a very hydrophilic anion undergoes transfer into the organic phase at a potential positive of 0.4 V (vs. Ag/AgCl) and may be employed as an ‘inert' background electrolyte. Chromate is shown to undergo electro‐insertion at low concentrations down to 10 μM. Within the oil phase chromate is undergoing condensation to the more stable dichromate.

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“…Over the whole range of pH used in the kinetic measurement UV-VIS studies showed that the potassium dichromate solution consist a shoulder at 450 nm, characteristic of the ion [15]. Measurement of…”

Section: Resultsmentioning

confidence: 99%

Kinetics and mechanism of chromic acid oxidation of oxalic acid in absence and presence of different acid media. A kinetic study

Khan¹,

Hashmi²,

Ahmed³

et al. 1998

Int. J. Chem. Kinet.

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Kinetics and mechanism of the reaction of Cr (VI) where only undissociated oxalic acid is kinetically active. Kinetic evidence for the formation of a Cr(VI)9 oxalic acid 1 : 1 complex has been obtained and the equilibrium constant for their formation has been determined. The 1 : 1 complex exists most likely in an open chain form. The rate-limiting step of the oxidation reaction involves the breaking of the C9 C bond in the 1 : 2 complex. Oxidizing ability of Cr(VI) species have been discussed. Mechanism with the associated reaction kinetics is assigned.

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Spectroscopy of chromium(VI) species

Cited by 77 publications

References 118 publications

Oxidation of D-gluconic acid by chromium(VI) in perchloric acid

Oxidation of D-gluconic acid by chromium(VI) in perchloric acid

Chromate and Dichromate Electro-Insertion Processes into a N,N,N′,N′-Tetraoctylphenylenediamine Redox Liquid

Kinetics and mechanism of chromic acid oxidation of oxalic acid in absence and presence of different acid media. A kinetic study

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