Analytical applications of reaction-rate-promoting effects.  Tris(1,10-phenanthroline)iron(II)-chromium(VI)indicator reaction

Dutt, V. V. S. Eswara; Mottola, Horacio A.

doi:10.1021/ac60344a024

Cited by 32 publications

(2 citation statements)

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“…These authors described the acceleration phenomenon as "promotion" and not catalysis, since the rate modifying species became inactive either by destruction or by complexation with the generated chromium(III). By judicious choice of reaction conditions and by employing initial reaction rate measurements, they quantified microgram amounts of oxalic and citric acid, vanadium(IV), arsenic(III), chromium(VI), hexacyanoferrate(III), and molybdenum(VI) (101). Dutt and Mottola (99) also observed that the ferroin-chromium(VI) reaction, accelerated by oxalic acid was preceded by an apparent induction period in the presence of uric acid.…”

Section: General Kinetic Papersmentioning

confidence: 99%

Kinetic aspects of analytical chemistry

Greinke¹,

Mark²

1976

Anal. Chem.

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Section: General Kinetic Papersmentioning

confidence: 99%

Kinetic aspects of analytical chemistry

Greinke¹,

Mark²

1976

Anal. Chem.

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“…In the case of PA-catalysis, PA is never cooxidised but is lost due to the formation of an inert Cr III -PA complex. Thus PA is not a true catalyst and it is better described as a promoter [2]. The chosen substrate, i.e.…”

Section: Introductionmentioning

confidence: 99%

Kinetic and Mechanistic Aspects of the Chromic Acid Oxidation of D-Galactose in the Presence and Absence of Picolinic Acid Catalyst in Aqueous Micellar Acid Media

Das

Islam

Das

et al. 2010

Progress in Reaction Kinetics and Mechanism

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The kinetics and mechanism of the chromic acid oxidation of D-galactose in the presence and absence of picolinic acid (PA) in aqueous acid media have been determined under the conditions, ½D À galactose T 4½Cr VI T at different temperatures. Under the kinetic conditions, HCrO 4 À has been found kinetically active in the absence of PA while in the PA catalysed path, a Cr VI -PA complex has been established as the active oxidant. In the PA-catalysed path, the Cr VI -PA complex receives a nucleophilic attack by the substrate to form a ternary complex which subsequently undergoes a redox decomposition through a two-electron transfer leading to a lactone (oxidised product) and a Cr IV -PA complex. Then the Cr IV -PA complex participates further in the oxidation of D-galactose and ultimately is converted into a Cr III -PA complex. In the uncatalysed path, a Cr VI -substrate ester experiences an acid catalysed redox decomposition (2e-transfer) at the ratedetermining step. The uncatalysed path shows a second-order dependence on [H þ ]. Under the experimental conditions, both paths show first-order dependences on [D-galactose] T and [Cr VI ] T . The PA-catalysed path is first-order in [PA] T . These observations remain unaltered in the presence of externally added surfactants. The effect of surfactants like N-cetylpyridinium chloride (CPC, a cationic surfactant) and sodium dodecyl sulfate (SDS, an anionic surfactant), on both the uncatalysed and PA-catalysed paths have been studied. CPC retards both the uncatalysed and PA-catalysed path, while SDS accelerates the reactions. The observed micellar effects have been explained by considering the hydrophobic and electrostatic interactions between the reactants and surfactants.

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