Oxidation and Reduction of Halogen‐containing Compounds

Peters, Dennis G.

doi:10.1002/9783527610426.bard080008

Cited by 3 publications

(3 citation statements)

References 158 publications

(156 reference statements)

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“…The following methods for substrate activation primarily involve cathodic reduction as oxidative methods are still underdeveloped but a few exceptions exist. , A classic electrochemical method of synthesizing cyclopropanes is cathodic reduction of either 1,3-dibromoalkanes or 1,3-di(methanesulfonate)alkanes to yield 1,3-difunctionalized alkanes. Electrolysis has proven useful for the reduction of alkyl halides and the formation of organometallic reagents in situ . − While the use of Zn dust to reduce 1,3-dibromopropane to afford cyclopropane in 56% yield was reported in 1882, its electrochemical analog was reported 85 years later by Rifi in 1967 . The method involves potentiostatic ( E c = −2.0 ± 0.1 V vs SCE), two-electron reduction of 3-bromopropyltriethylammonium bromide, which forms a highly reactive carbanion that undergoes intramolecular substitution at the alkylammonium to eject triethylamine and form cyclopropane (yield not reported).…”

Section: Synthetic Comparisons Between Photoredox Catalysis and Elect...mentioning

confidence: 99%

Photons or Electrons? A Critical Comparison of Electrochemistry and Photoredox Catalysis for Organic Synthesis

2021

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Redox processes are at the heart of synthetic methods that rely on either electrochemistry or photoredox catalysis, but how do electrochemistry and photoredox catalysis compare? Both approaches provide access to high energy intermediates (e.g., radicals) that enable bond formations not constrained by the rules of ionic or 2 electron (e) mechanisms. Instead, they enable 1e mechanisms capable of bypassing electronic or steric limitations and protecting group requirements, thus enabling synthetic chemists to disconnect molecules in new and different ways. However, while providing access to similar intermediates, electrochemistry and photoredox catalysis differ in several physical chemistry principles. Understanding those differences can be key to designing new transformations and forging new bond disconnections. This review aims to highlight these differences and similarities between electrochemistry and photoredox catalysis by comparing their underlying physical chemistry principles and describing their impact on electrochemical and photochemical methods.

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Section: Synthetic Comparisons Between Photoredox Catalysis and Elect...mentioning

confidence: 99%

Photons or Electrons? A Critical Comparison of Electrochemistry and Photoredox Catalysis for Organic Synthesis

2021

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“…Electrochemical reduction of halogenated organic compounds has been studied extensively, and numerous reviews − have appeared since 1980. These reviews, along with their extensive bibliographies, clearly reveal that the reductive cleavage of carbon–halogen bonds in environmental pollutants is a complicated process that is affected by at least four parameters: (a) the structural features of the molecule of interest, (b) the identity of the cathode material, (c) the particular solvent/electrolyte combination that is employed, and (d) the potential of the cathode itself.…”

Section: Halogenated Environmental Pollutantsmentioning

confidence: 99%

Electroreductive Remediation of Halogenated Environmental Pollutants

et al. 2016

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Electrochemical reduction of halogenated organic compounds is gaining increasing attention as a strategy for the remediation of environmental pollutants. We begin this review by discussing key components (cells, electrodes, solvents, and electrolytes) in the design of a procedure for degrading a targeted pollutant, and we describe and contrast some experimental techniques used to explore and characterize the electrochemical behavior of that pollutant. Then, we describe how to probe various mechanistic features of the pertinent electrochemistry (including stepwise versus concerted carbon-halogen bond cleavage, identification of reaction intermediates, and elucidation of mechanisms). Knowing this information is vital to the successful development of a remediation procedure. Next, we outline techniques, instrumentation, and cell designs involved in scaling up a benchtop experiment to an industrial-scale system. Finally, the last and major part of this review is directed toward surveying electrochemical studies of various categories of halogenated pollutants (chlorofluorocarbons; disinfection byproducts; pesticides, fungicides, and bactericides; and flame retardants) and looking forward to future developments.

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“…The electrocatalytic reduction of organic halides has received much attention in the last few decades. [1][2][3] Silver as an electrode material has been found to possess extraordinary electrocatalytic properties 4,5 which have been utilized in synthetic [6][7][8][9] and environmental applications. [10][11][12] The reduction of carbon-halogen bonds has also attracted much interest as a model process for the investigation of dissociative electron transfers (DETs) which occur at 'inert' electrodes (for example at platinum and glassy carbon (GC)).…”

Section: Introductionmentioning

confidence: 99%

Electrocatalytic reduction of alkyl iodides in tetrahydrofuran at silver electrodes

Paddon

Bhatti

Donohoe

et al. 2007

J of Physical Organic Chem

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Recent interest in the electrocatalytic activity of silver towards the reduction of alkyl iodides has led us to investigate whether the effect is observed in tetrahydrofuran (THF) at room temperature. Using platinum electrodes in THF for the reduction of alkyl halides at 298 K has been hampered by the solvent window, which 'obscures' the voltammetric signals of interest. In order to overcome these problems, voltammetry has been performed at low temperature and was shown to extend the voltammetric window, leading to accurate electrochemical analyses and even novel changes in mechanism(s) of the reactive species following electron-transfer (ET). Herein, it is shown that for a primary and tertiary alkyl iodide in THF, electroreduction at silver leads to a significant shift in the reduction potential to more positive values compared to platinum. In addition, following reduction, a characteristic series of oxidation peaks are observed and are shown to be due to the specific activity of iodide ions towards silver following reductive cleavage of the parent alkyl iodide. This characteristic feature is not observed with other halide ions: bromide and chloride. Preparative electrolyses at controlled-potential have suggested that the reduction of the above alkyl iodides is a one-electron concerted process. The 'free' iodide ions act as a monitor of reaction progression, and the carbon-centred radical either dimerises and/or abstracts a hydrogen atom from the electrolyte/solvent; 1-iodoadamantane giving percentage yields of 58% adamantane and 39% 1,1'-biadamantane, the primary alkyl iodide, prepared in-house, giving 67% R-H and 25% R-R.

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Oxidation and Reduction of Halogen‐containing Compounds

Abstract: The sections in this article are Introduction Anodic Processes Halogenated Alkanes Alicyclic Halides Aryl Halides Cathodic Processes Halogenated Alkanes Halogenated Alkenes and Alkynes Benzyl Halid… Show more

Cited by 3 publications

References 158 publications

Photons or Electrons? A Critical Comparison of Electrochemistry and Photoredox Catalysis for Organic Synthesis

Photons or Electrons? A Critical Comparison of Electrochemistry and Photoredox Catalysis for Organic Synthesis

Electroreductive Remediation of Halogenated Environmental Pollutants

Electrocatalytic reduction of alkyl iodides in tetrahydrofuran at silver electrodes

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