Suppressing carboxylate nucleophilicity with inorganic salts enables selective electrocarboxylation without sacrificial anodes

Corbin, Nathan; Yang, Deng‐Tao; Lazouski, Nikifar; Steinberg, Katherine; Manthiram, Karthish

doi:10.1039/d1sc02413b

Cited by 45 publications

(46 citation statements)

References 80 publications

(93 reference statements)

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“…Further tuning of the model could consider possible specific stabilization of the species involved and, in particular, of the charged ones by the nature of the solvent or by the presence of additives. As discussed by ( Pletcher and Slevin, 1996 ), Mg 2+ ions are known to stabilize reduced intermediates and carboxylate species ( Corbin et al, 2021 ) and are proposed to play a key role in the electrochemical carboxylation of benzalacetone (Mg 2+ are typically generated under electrochemical conditions, when employing Mg sacrificial anodes) ( Wang et al, 2017 ; Bhasha Sayyed and Sakaki, 2014 ).…”

Section: Discussionmentioning

confidence: 99%

Basicity as a Thermodynamic Descriptor of Carbanions Reactivity with Carbon Dioxide: Application to the Carboxylation of α,β-Unsaturated Ketones

et al. 2021

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The utilization of carbon dioxide as a raw material represents nowadays an appealing strategy in the renewable energy, organic synthesis, and green chemistry fields. Besides reduction strategies, carbon dioxide can be exploited as a single-carbon-atom building block through its fixation into organic scaffolds with the formation of new C-C bonds (carboxylation processes). In this case, activation of the organic substrate is commonly required, upon formation of a carbanion C−, being sufficiently reactive toward the addition of CO2. However, the prediction of the reactivity of C− with CO2 is often problematic with the process being possibly associated with unfavorable thermodynamics. In this contribution, we present a thermodynamic analysis combined with density functional theory calculations on 50 organic molecules enabling the achievement of a linear correlation of the standard free energy (ΔG0) of the carboxylation reaction with the basicity of the carbanion C−, expressed as the pKa of the CH/C− couple. The analysis identifies a threshold pKa of ca 36 (in CH3CN) for the CH/C− couple, above which the ΔG0 of the carboxylation reaction is negative and indicative of a favorable process. We then apply the model to a real case involving electrochemical carboxylation of flavone and chalcone as model compounds of α,β-unsaturated ketones. Carboxylation occurs in the β-position from the doubly reduced dianion intermediates of flavone and chalcone (calculated ΔG0 of carboxylation in β = −12.8 and −20.0 Kcalmol-1 for flavone and chalcone, respectively, associated with pKa values for the conjugate acids of 50.6 and 51.8, respectively). Conversely, the one-electron reduced radical anions are not reactive toward carboxylation (ΔG0 > +20 Kcalmol-1 for both substrates, in either α or β position, consistent with pKa of the conjugate acids < 18.5). For all the possible intermediates, the plot of calculated ΔG0 of carboxylation vs. pKa is consistent with the linear correlation model developed. The application of the ΔG0 vs. pKa correlation is finally discussed for alternative reaction mechanisms and for carboxylation of other C=C and C=O double bonds. These results offer a new mechanistic tool for the interpretation of the reactivity of CO2 with organic intermediates.

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Section: Discussionmentioning

confidence: 99%

Basicity as a Thermodynamic Descriptor of Carbanions Reactivity with Carbon Dioxide: Application to the Carboxylation of α,β-Unsaturated Ketones

et al. 2021

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“…A cation generated from anode oxidation coordinates with a carboxylate and prevents carboxylate from a further nucleophilic addition reaction. One potential solution is to add anhydrous magnesium bromide to decrease the nucleophilicity of carboxylate and carbonate anions and prevent the side product (i.e., ester and alcohol) formation through an S N 2 reaction . However, the use of anhydrous magnesium bromide is limited by its scarcity and the economic feasibility should be considered on the basis of the production scale and product value.…”

Section: Electroreduction Of Co2 and Co To Petrochemicalsmentioning

confidence: 99%

Emerging Electrochemical Processes to Decarbonize the Chemical Industry

Rong

Overa

Jiao

2022

JACS Au

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Electrification is a potential approach to decarbonizing the chemical industry. Electrochemical processes, when they are powered by renewable electricity, have lower carbon footprints in comparison to conventional thermochemical routes. In this Perspective, we discuss the potential electrochemical routes for chemical production and provide our views on how electrochemical processes can be matured in academic research laboratories for future industrial applications. We first analyze the CO 2 emission in the manufacturing industry and conduct a survey of state of the art electrosynthesis methods in the three most emission-intensive areas: petrochemical production, nitrogen compound production, and metal smelting. Then, we identify the technical bottlenecks in electrifying chemical productions from both chemistry and engineering perspectives and propose potential strategies to tackle these issues. Finally, we provide our views on how electrochemical manufacturing can reduce carbon emissions in the chemical industry with the hope to inspire more research efforts in electrifying chemical manufacturing.

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“…[75,79] Dabei werden die wenig reaktiven Alund Mg-Carboxylate in situ gebildet, wodurch die Kolbe-Reaktion des gebildeten Produkts als mögliche Nebenreaktion an der Anode unterdrückt wird. [80] Der signifikante Einfluss der gelösten Kationen wurde von Frontana-Uribe et al in der elektrochemischen Horner-Wadsworth-Emmons-Reaktion zur Synthese von (E)-ungesättigten Estern nachgewiesen (Schema 14). Die kathodische Deprotonierung des Phosphonats treibt die Reaktion an, wobei keine zusätzliche Base benötigt wird.…”

Section: Angewandte Chemieunclassified

Reaktionen an der Gegenelektrode – wichtige Stolpersteine auf dem Weg einer funktionierenden elektro‐organischen Synthese

Klein

Waldvogel

2022

Angewandte Chemie

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In den letzten zwei Jahrzehnten hat die elektro‐organische Synthese signifikant an Interesse gewonnen, sowohl in technischer und akademischer Forschung als auch in der Anwendung. Der Verzicht auf Oxidations‐ und Reduktionsmittel in stöchiometrischen Mengen ermöglicht eine nachhaltigere Alternative, Redoxreaktionen in der organischen Chemie durchzuführen. Auch wenn bekannt ist, dass jede elektrochemische Oxidation nur zusammen mit einer assoziierten Reduktion durchführbar ist und umgekehrt, wird die Relevanz der Gegenreaktion oft wenig beachtet. In diesem Aufsatz wird die Bedeutung der korrespondierenden Gegenreaktion beleuchtet und welchen Einfluss diese auf die Durchführbarkeit und Selektivität einer elektrochemischen Umsetzung hat. Anhand einer Auswahl üblicher Strategien und einzigartiger Konzepte werden Lösungen für dieses Problem aufgeführt. Dies ergibt einen Leitfaden zur Auswahl geeigneter Gegenreaktionen in der elektro‐organischen Synthese.

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Suppressing carboxylate nucleophilicity with inorganic salts enables selective electrocarboxylation without sacrificial anodes

Abstract: Although electrocarboxylation reactions use CO2 as a renewable synthon and can incorporate renewable electricity as a driving force, the overall sustainability and practicality of this process is limited by the...

Cited by 45 publications

References 80 publications

Basicity as a Thermodynamic Descriptor of Carbanions Reactivity with Carbon Dioxide: Application to the Carboxylation of α,β-Unsaturated Ketones

Basicity as a Thermodynamic Descriptor of Carbanions Reactivity with Carbon Dioxide: Application to the Carboxylation of α,β-Unsaturated Ketones

Emerging Electrochemical Processes to Decarbonize the Chemical Industry

Reaktionen an der Gegenelektrode – wichtige Stolpersteine auf dem Weg einer funktionierenden elektro‐organischen Synthese

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