Iron(III)-(II) couple in acetonitrile.  Oxidation of thiocyanate by iron(III)

Kratochvil, Byron; Long, Robert Bryan

doi:10.1021/ac60283a025

Cited by 44 publications

(23 citation statements)

References 8 publications

(1 reference statement)

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“…This can be illustrated using [C 2 mim][SCN] as an example: the UV-Vis spectrum exhibits an absorption band at 480 nm, which is typical for an Fe(III) thiocyanate complex. [50][51][52] Therefore, ferrocene is not a suitable redox standard for these liquids.…”

Section: Speciation Studiesmentioning

confidence: 99%

Voltammetric and spectroscopic study of ferrocene and hexacyanoferrate and the suitability of their redox couples as internal standards in ionic liquids

Frenzel

Hartley

Frisch

2017

Phys. Chem. Chem. Phys.

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Ionic liquids and deep eutectic solvents have great potential in metallurgical applications as specialised solvents. In order to design ionometallurgical electrowinning and electrorefining processes, it is essential to characterise the electrochemical behaviour of metal complexes and compare potentials between relevant solvents. For such investigations, a universal reference redox couple would be desirable. In this study we investigate the speciation and electrochemical behaviour of ferrocenium/ferrocene and hexacyanoferrate(iii/ii) as possible reference couples for 15 different ionic media on platinum (Pt), glassy carbon (GC) and gold (Au) working electrodes. Amongst other parameters, formal electrode potentials, charge transfer coefficients, and rate constants were calculated. It was found that neither ferrocene nor hexacyanoferrate are universally suitable as redox standards in the liquids investigated. Nevertheless, hexacyanoferrate exhibits clear advantages in most of the strongly coordinating ionic liquids studied here.

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Section: Speciation Studiesmentioning

confidence: 99%

Voltammetric and spectroscopic study of ferrocene and hexacyanoferrate and the suitability of their redox couples as internal standards in ionic liquids

Frenzel

Hartley

Frisch

2017

Phys. Chem. Chem. Phys.

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“…6 Such a major mechanistic change caused by a modest change in reaction conditions led us to 3 consider the effect of other parameters, including solvent, on reactions involving solvento iron species in oxidation states 2+ to 4+. Specifically, the much higher reduction potential of the Fe(III)/Fe(II) couple in acetonitrile 7,8 as compared to that in water suggests that the preference for two-electron pathways of a hypothetical iron(IV) species might be greater in acetonitrile. To explore this possibility and its potential consequences for iron-catalyzed oxidations, we initiated a study of the reaction of Fe(II) with O 3 in acetonitrile in the presence of oxidizable substrates.…”

Section: Methodsmentioning

confidence: 99%

Iron(II) Catalysis in Oxidation of Hydrocarbons with Ozone in Acetonitrile

2015

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Oxidation of alcohols, ethers, and sulfoxides by ozone in acetonitrile is catalyzed by sub-millimolar concentrations of Fe(CH 3 CN) 6 2+ . The catalyst provides both rate acceleration and greater selectivity toward the less oxidized products. For example, Fe(CH 3 CN) 6 2+ -catalyzed oxidation of benzyl alcohol yields benzaldehyde almost exclusively (>95%) whereas uncatalyzed reaction generates a 1:1 mixture of benzaldehyde and benzoic acid. Similarly, aliphatic alcohols are oxidized to aldehydes/ketones, cyclobutanol to cyclobutanone, and diethyl ether to a 1:1 mixture of ethanol and acetaldehyde. The kinetics of oxidation of alcohols and diethyl ether are first order in [Fe(CH 3 CN) 6 2+ ] and [O 3 ], and independent of [Substrate] at concentrations greater than ~5 mM. In this regime, the rate constant for all of the alcohols is approximately the same, k cat = (8±1) × 10 4 M -1 s -1 , and that for (C 2 H 5 ) 2 O is (5±0.5) × 10 4 M -1 s -1 . In the absence of substrate, Fe(CH 3 CN) 6 2+ reacts with O 3 with k Fe = (9.3±0.3) × 10 4 M -1 s -1 . The similarity between the rate constants k Fe and k cat strongly argues for Fe(CH 3 CN) 6 2+ /O 3 reaction as rate determining in catalytic oxidation. The active oxidant produced in Fe(CH 3 CN) 6 2+ /O 3 reaction is suggested to be an Fe(IV) species in analogy with a related intermediate in aqueous solutions.This assignment is supported by the similarity in kinetic isotope effects and relative reactivities of the two species toward substrates.

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“…Table 4.5 Standard potentials in acetonitrile (25 C) [12,13]. Table 4.5 Standard potentials in acetonitrile (25 C) [12,13].…”

Section: Titrations With Oxidizing Agentsmentioning

confidence: 99%

“…Figure 4.11 shows the curve obtained by titrating SCN À in AN with hydrated Fe(III) [13]. Fe(III) has been used to titrate SCN À , I À and various organic compounds in AN.…”

Section: Titrations With Oxidizing Agentsmentioning

confidence: 99%

Redox Reactions in Nonaqueous Solvents

Izutsu¹

2009

Electrochemistry in Nonaqueous Solutions

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Iron(III)-(II) couple in acetonitrile. Oxidation of thiocyanate by iron(III)

Cited by 44 publications

References 8 publications

Voltammetric and spectroscopic study of ferrocene and hexacyanoferrate and the suitability of their redox couples as internal standards in ionic liquids

Voltammetric and spectroscopic study of ferrocene and hexacyanoferrate and the suitability of their redox couples as internal standards in ionic liquids

Iron(II) Catalysis in Oxidation of Hydrocarbons with Ozone in Acetonitrile

Redox Reactions in Nonaqueous Solvents

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