Electrochemical Conversion of Cyanide into Methylamine and C<sub>1</sub>−C<sub>2</sub> Hydrocarbons

Fedurco, Milan; Sartoretti, C. Jorand; Augustyński, Jan

doi:10.1021/ja983747m

Cited by 10 publications

(4 citation statements)

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“…DeWulf et al and Hori et al proposed that electrochemical hydrogenation of CO 2 on polycrystalline copper in aqueous carbonate solutions might involve adsorbed carbene. More recently, we have suggested that carbene and methyl radicals are the reaction intermediates in the process of cyanide electroreduction on group IB metals and nickel . One of the main goals of the present work was to generate these species directly at the group IB metal/solution interface from sources other than CO 2 , CO, or HCN and to investigate how their reactivities change with the nature of the electrode and of the electrolyte.…”

Section: Introductionmentioning

confidence: 97%

Reductive Cleavage of the Carbon−Halogen Bond in Simple Methyl and Methylene Halides. Reactions of the Methyl Radical and Carbene at the Polarized Electrode/Aqueous Solution Interface

2001

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Reactivities of methyl radical and carbene species, electrogenerated on the surfaces of group IB metals via reductive cleavage of simple methyl and methylene halides (bromides and iodides) in aqueous solution, are investigated using cyclic voltammetry associated with the products' identification by gas chromatography/ mass spectrometry. To appreciate specific changes in the electrochemical behavior of the above halides, related to the nature of the electrode material, similar measurements have also been carried out employing an inert glassy carbon electrode. The replacement of glassy carbon by the group IB metals Ag and Cu was found to lead to a sensible shift (several hundred mV) in their reduction potentials (Ep). Consequently, the reduction of CH2Br2, CH2I2, and CH3I starts at potentials positive with respect to the potentials of zero charge (pzc) of Ag and Cu, producing significant amounts of ethylene and ethane, respectively. Methane becomes the dominant reaction product only at the potentials more negative than Ep. The extent of interaction between the reaction intermediates and the electrode surface clearly depends not only on the potential but also on the electronic structure of the electrode. This was confirmed by the results of experiments conducted using the Au and glassy carbon electrodes, having pzc values much more positive than Ag and Cu, at which methane was the only detected product of the CH3X and CH2X2 reduction, over the entire range of potentials. The collected results demonstrate that the reactions undergone by the electrogenerated CH2 and • CH3 species can be oriented toward formation of either ethylene/ethane or methane by a suitable choice of the electrode material and of the range of applied potentials. The use in this study of Ag and Cu electrodes allows generation of the CH2 and • CH3 radicals above the onset potential for H2 evolution, so that their reactivity can be investigated virtually in the absence of competing reactions.

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Section: Introductionmentioning

confidence: 97%

Reductive Cleavage of the Carbon−Halogen Bond in Simple Methyl and Methylene Halides. Reactions of the Methyl Radical and Carbene at the Polarized Electrode/Aqueous Solution Interface

2001

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“…1 Although this conclusion remains essentially correct with regard to the Pt cathode, it cannot be extended to all electrode materials. In fact, we have recently reported 2 that the electroreduction of an almost neutral HCN solution, conducted using a nickel or a copper cathode, results in the formation of substantial amounts of methylamine, methane, and ammonia according to Reactions 1 and 2…”

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confidence: 99%

Electrochemical Reduction of Cyanides at Metallic Cathodes: A Comparison with Biological HCN Reduction

Fedurco

Sartoretti

Augustyński

2001

J. Electrochem. Soc.

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The electrochemical reduction of cyanides has been studied at a number of cathodes both in near-neutral and in alkaline solutions. Nickel appears as the most effective cathode material, promoting cyanide reduction with current efficiencies close to 70%, even in moderately alkaline solutions. In all cases, the eletroreduction of cyanides leads to a mixture of 4e Ϫ ͑methylamine͒ and 6e Ϫ products ͑methane and ammonia͒. The use of Nafion films loaded with Ni microparticles enabled us to markedly increase the effective current densities for cyanide reduction. The electrochemical reduction of HCN/CN Ϫ is shown to present interesting similarities and differences with the biological cyanide reduction process.Until recently, cyanides ͑i.e., CN Ϫ ions and HCN͒ were considered to be unreducible electrochemically in aqueous solution. In fact, the cathodic wave recorded at a platinum electrode immersed in an HCN ͑aq͒ solution was traditionally assigned to hydrogen evolution. 1 Although this conclusion remains essentially correct with regard to the Pt cathode, it cannot be extended to all electrode materials. In fact, we have recently reported 2 that the electroreduction of an almost neutral HCN solution, conducted using a nickel or a copper cathode, results in the formation of substantial amounts of methylamine, methane, and ammonia according to Reactions 1 and 2In contrast with the results of electrolyses conducted with Ni and Cu cathodes, only traces of the cyanide conversion products were formed at a Pt electrode. It is to be noted, however, that nitriles, including HCN, undergo chemisorption on Pt, both in the doublelayer and hydrogen-adsorption regions, and can be partially reduced and then reoxidized in the adsorbed state without formation of solution-soluble products. 3,4 In this paper, the behavior of a number of electrode materials is examined in an attempt to explain the large differences in their electrocatalytic properties toward cyanide reduction. It is shown that some metals and, in particular, nickel, promote also quite efficiently the cyanide reduction in alkaline solutions. Significant faradaic yields are maintained when operating at high ͑apparent͒ current densities using dispersed Ni cathodes. ExperimentalAll experiments were performed in two-compartment cells made either of glass or Teflon. A platinum counter electrode ͑large-area Pt grid͒ was separated from a working electrode either by a Nafion membrane or a ceramic frit. A cross section of metal ͑Ag, Au, Cu, Ni͒ rods, 3 mm diam ͑Specpure 99.999%, Johnson Matthey͒ or larger metal sheets of Pt and Pd, ͑from 0.25 to 1.0 cm 2 ͒ served in various experiments as working electrodes. The electrode surface was prepared by polishing the metals mechanically with fine emery papers and then with suspensions of 1.0 and 0.3 m alumina powders. Alumina was removed from the electrode surface via sonication in an ultrasonic bath and washing with copious amount of distilled water. Before the measurements, the electrode surface was cleaned by cycling the potential into the...

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“…The literature reports the electrochemical reduction of cyanides at different types of working electrodes in acidic, neutral and alkaline solutions [42,43] with different reaction mechanisms [42]. Nitrile compounds were considered to be electrochemically non-reducible in aqueous solutions at mercury electrodes [44], but reducible at nickel, copper, and silver electrodes [45]. Nevertheless, nitrile reduction at mercury electrodes has also been reported [42].…”

Section: Electrochemical Studymentioning

confidence: 99%

Voltammetric and corrosion studies of the fungicide fludioxonil

Brycht

Burnat

Skrzypek

et al. 2015

Electrochimica Acta

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Electrochemical Conversion of Cyanide into Methylamine and C₁−C₂ Hydrocarbons

Cited by 10 publications

References 22 publications

Reductive Cleavage of the Carbon−Halogen Bond in Simple Methyl and Methylene Halides. Reactions of the Methyl Radical and Carbene at the Polarized Electrode/Aqueous Solution Interface

Reductive Cleavage of the Carbon−Halogen Bond in Simple Methyl and Methylene Halides. Reactions of the Methyl Radical and Carbene at the Polarized Electrode/Aqueous Solution Interface

Electrochemical Reduction of Cyanides at Metallic Cathodes: A Comparison with Biological HCN Reduction

Voltammetric and corrosion studies of the fungicide fludioxonil

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Electrochemical Conversion of Cyanide into Methylamine and C1−C2 Hydrocarbons

Cited by 10 publications

References 22 publications

Reductive Cleavage of the Carbon−Halogen Bond in Simple Methyl and Methylene Halides. Reactions of the Methyl Radical and Carbene at the Polarized Electrode/Aqueous Solution Interface

Reductive Cleavage of the Carbon−Halogen Bond in Simple Methyl and Methylene Halides. Reactions of the Methyl Radical and Carbene at the Polarized Electrode/Aqueous Solution Interface

Electrochemical Reduction of Cyanides at Metallic Cathodes: A Comparison with Biological HCN Reduction

Voltammetric and corrosion studies of the fungicide fludioxonil

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Electrochemical Conversion of Cyanide into Methylamine and C₁−C₂ Hydrocarbons