Effect of Sodium Ions on the Electrochemical Reduction of Diethyl Fumarate in Dimethylsulfoxide and Acetonitrile

Evans, Dennis H.

doi:10.1149/1.2401943

Cited by 22 publications

(4 citation statements)

References 13 publications

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“…As in the homogeneous case, specific interactions involving ion-pairs strongly influence the thermodynamics and kinetics of electrochemical electron-transfer reactions . They may also influence the mechanisms and kinetics of follow-up reactions. − Ion-pairing is also deemed to play an important role in the thermodynamics and kinetics of electron-transfer reactions in the actively investigated room-temperature ionic liquids. − …”

Section: Introductionmentioning

confidence: 99%

Evidence for Concerted Pathways in Ion-Pairing Coupled Electron Transfers

Savéant

2008

J. Am. Chem. Soc.

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Ion-pairing with electro-inactive metal ions may change drastically the thermodynamic and kinetic reactivity of electron transfer in chemical and biochemical processes. Besides the classical stepwise pathways (electron-transfer first, followed by ion-pairing or vice versa), ion-pairing may also occur concertedly with electron transfer. The latter pathway avoids high-energy intermediates but a key issue is that of the kinetic price to pay to benefit from this thermodynamic advantage. A model is proposed leading to activation/driving force relationships characterizing such concerted associative electron transfers for intermolecular and intramolecular homogeneous reactions and for electrochemical reactions. Contrary to previous assertions, the driving force of the reaction (defined as the opposite of the reaction standard free energy), as well as the intrinsic barrier, does not depend on the concentration of the ion-pairing agent, which simply plays the role of one of the reactants. Besides solvent and intramolecular reorganization, the energy of the bond being formed is the main component of the intrinsic barrier. Application of these considerations to reactions reported in recent literature illustrates how concerted ion-pairing electron-transfer reactions can be diagnosed and how competition between stepwise and concerted pathways can be analyzed. It provided the first experimental evidence of the viability of concerted ion-pairing electron-transfer reactions.

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Section: Introductionmentioning

confidence: 99%

Evidence for Concerted Pathways in Ion-Pairing Coupled Electron Transfers

Savéant

2008

J. Am. Chem. Soc.

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“…In such solvents, dealing with species formed upon single electron transfer to neutral molecules, the extent of ion pairing is usually moderate. Its influence on the course of the electrochemical reaction may thus be depicted in most cases as triggered by a change in the reaction thermodynamics. − More dramatic consequences in terms of mechanisms and kinetics are anticipated for larger values of the association constant as those encountered in solvents of low dielectric constants, such as ethers or polyhalogenated hydrocarbons (dielectric constants of the order of 5−10). Species resulting from a second electron transfer are even more prone to ion pairing than first electron-transfer products.…”

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confidence: 99%

Effect of Ion Pairing on the Mechanism and Rate of Electron Transfer. Electrochemical Aspects

Savéant

2001

J. Phys. Chem. B

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Ion pairing may have a strong influence on the kinetics and mechanisms of electrochemical reactions as reflected by the location of the corresponding half-wave (or peak) potential. Upon increasing the extent of ion pairing (by increasing the binding constant and/ or the concentration of associating ion), the following changes are expected, taking a reductive formation of the ion pair as example. For moderate ion pairing and fast electron transfer, a positive shift of the reversible half-wave (or peak) potential by 59.6 mV (at 25 °C) per 10-fold increase of the associating ion concentration is predicted. Next, fast and strong ion pairing prompts the forward electron transfer to become rate determining. On the oxidation side, a predissociation mechanism, involving a positive shift of the wave, prevails as long as the extent of ion pairing is not too large. Upon increasing the extent of ion pairing, the height of the predissociation wave rapidly drops to zero. Direct electron transfer to the ion pair, associated with the expulsion of the associating ion, then takes place according to a mechanism in which the breaking of the ion-pair bond is successive to or concerted with electron transfer. In the latter case, the applicability of the dissociative electron-transfer theory previously developed for reductive cleavages is discussed based on appropriate quantum chemical computations.

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“…Entry 9 shows that mediator 2 also activates BnCl but in low yield and entry 10 as a control experiment, proves that the presence of mediator is key for the generation of benzyl radical and production of 5 . The direct reduction of fumarate produces rapid dimerization according to the literature [20] and consequently 5 is not formed when compared to a standard of the isolated product (TLC). In fact, the products of such run (entry 10) were of lower polarity than other runs with higher R f than the previously obtained and 1 H‐NMR of the reaction crudes showed peaks dispersed in a larger region of the spectrum supporting dimerization/oligomerization (see SI, section 7).…”

Section: Resultsmentioning

confidence: 99%

N‐(aminobenzyliden)phthalimides as a New Redox Mediator Family for the Selective Indirect Reduction of Benzyl or Allyl Halides

Patiño‐Alonzo,

Barroso‐Flores,

Frontana‐Uribe

2023

ChemCatChem

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The chemical stability of the electrogenerated radical anion of N‐(aminobenzyl) phthalimide 1 in aprotic organic media at room temperature is reported in this work. The redox couples 1/1⋅− and its imine precursor 2/2⋅− can carry out reductive redox catalysis of benzyl or allyl halides indirectly. This reaction gives easy access to reactive alkyl radicals, which in the presence of diethyl fumarate yields 2‐benzylsuccinate diethyl ester in moderate yields; this reaction is unattainable by direct electrochemical reduction. Spin density calculations at the DFT level of theory showed that the spin density of 1⋅− and 2⋅− is located on the phtalimide ring, and a dimeric association was evidenced (Eint=23.47 kcal/mol and Eint=80.42 kcal/mol respectively), via π−π stacking interactions. The redox mediators presented here showed good functional group selectivity, redox potential tunability and easy preparation from readily available commercial materials with excellent yields.

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Effect of Sodium Ions on the Electrochemical Reduction of Diethyl Fumarate in Dimethylsulfoxide and Acetonitrile

Abstract: not Available.

Cited by 22 publications

References 13 publications

Evidence for Concerted Pathways in Ion-Pairing Coupled Electron Transfers

Evidence for Concerted Pathways in Ion-Pairing Coupled Electron Transfers

Effect of Ion Pairing on the Mechanism and Rate of Electron Transfer. Electrochemical Aspects

N‐(aminobenzyliden)phthalimides as a New Redox Mediator Family for the Selective Indirect Reduction of Benzyl or Allyl Halides

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