The Fundamentals Behind the Use of Flow Reactors in Electrochemistry

Accounts of Chemical Research, Journal Year: 2019, Volume and Issue: 52(10), P. 2858 - 2869

Published: Oct. 1, 2019

In the past decade, research into continuous-flow chemistry has gained a lot of traction among researchers in both academia and industry. Especially, microreactors have received plethora attention due to increased mass heat transfer characteristics, possibility increase process safety, potential implement automation protocols analytical technology. Taking advantage these aspects, chemists chemical engineers capitalized on expanding space available synthetic organic using this Electrochemistry recently witnessed renaissance interests as it provides unique tunable opportunities carry out redox electrons traceless reagents, thus effectively avoiding use hazardous toxic reductants oxidants. The popularity electrochemistry stems also from harvest sustainable electricity, derived solar wind energy. Hence, electrification industry offers an opportunity locally produce commodity chemicals, reducing inefficiencies with regard transportation storage chemicals. combination flow technology practitioners great control over reaction conditions, improving reproducibility electrochemistry. However, carrying electrochemical reactions is more complicated than just pumping chemicals through narrow-gap electrolytic cell. Understanding engineering principles behind observations can help exploit full Thus, prime objective Account provide readers overview underlying aspects which are associated This includes discussion relevant transport phenomena encountered reactors. Next, we discuss integrate several steps single streamlined challenging multiphase transformations flow. Due high transfer, be carried precision enhance tune selectivity. Finally, detail scale-up importance small interelectrode gaps pilot industrial-scale processes. Each principle been illustrated example. general, aimed describe simple words minimum equations attract engage background. anticipate that will serve useful guide fascinating world

Language: Английский

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New Redox Strategies in Organic Synthesis by Means of Electrochemistry and Photochemistry

ACS Central Science, Journal Year: 2020, Volume and Issue: 6(8), P. 1317 - 1340

Published: July 16, 2020

As the breadth of radical chemistry grows, new means to promote and regulate single-electron redox activities play increasingly important roles in driving modern synthetic innovation. In this regard, photochemistry electrochemistry-both considered as niche fields for decades-have seen an explosive renewal interest recent years gradually have become a cornerstone organic chemistry. Outlook article, we examine current state-of-the-art areas electrochemistry photochemistry, well nascent area electrophotochemistry. These techniques employ external stimuli activate molecules imbue privileged control reaction progress selectivity that is challenging traditional chemical methods. Thus, they provide alternative entries known reactive intermediates enable distinct strategies were previously unimaginable. Of many hallmarks, electro- are often classified "green" technologies, promoting reactions under mild conditions without necessity potent wasteful oxidants reductants. This reviews most growth these with special emphasis on conceptual advances given rise enhanced accessibility tools trade.

Language: Английский

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

Chemical Reviews, Journal Year: 2021, Volume and Issue: 122(2), P. 2487 - 2649

Published: Nov. 9, 2021

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

Language: Английский

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Photochemical and Electrochemical Applications of Proton-Coupled Electron Transfer in Organic Synthesis

Chemical Reviews, Journal Year: 2021, Volume and Issue: 122(2), P. 2017 - 2291

Published: Nov. 23, 2021

We present here a review of the photochemical and electrochemical applications multi-site proton-coupled electron transfer (MS-PCET) in organic synthesis. MS-PCETs are redox mechanisms which both an proton exchanged together, often concerted elementary step. As such, MS-PCET can function as non-classical mechanism for homolytic bond activation, providing opportunities to generate synthetically useful free radical intermediates directly from wide variety common functional groups. introduction practitioner’s guide reaction design, with emphasis on unique energetic selectivity features that characteristic this class. then chapters oxidative N–H, O–H, S–H, C–H homolysis methods, generation corresponding neutral species. Then, reductive PCET activations involving carbonyl, imine, other X═Y π-systems, heteroarenes, where ketyl, α-amino, heteroarene-derived radicals be generated. Finally, we asymmetric catalysis materials device applications. Within each chapter, subdivide by group undergoing homolysis, thereafter type transformation being promoted. Methods published prior end December 2020 presented.

Language: Английский

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Sulfonyl fluorides as targets and substrates in the development of new synthetic methods

Nature Reviews Chemistry, Journal Year: 2022, Volume and Issue: 6(2), P. 146 - 162

Published: Jan. 19, 2022

Language: Английский

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Recent Advances in Electrochemical Systems for Selective Fluorination of Organic Compounds

Accounts of Chemical Research, Journal Year: 2020, Volume and Issue: 53(2), P. 322 - 334

Published: Feb. 4, 2020

Organofluorine compounds are key materials applied in daily life because of their versatile utility as functional materials, pharmaceuticals, and agrochemicals. Development the selective fluorination organic molecules under safe conditions is therefore one most important subjects modern synthetic organofluorine chemistry. Thus, various electrophilic reagents such XeF2, (PhSO2)2NF (NFSI), Et2NSF3 (DAST), (MeOCH2CH2)2NSF3 (Deoxofluor), 1-chloromethyl-4-fluoro-1,4-diazoniabicyclo-[2.2.2]octane bis(tetrafluoroborate) (Selectfluor), N-fluoropyridinium salts, 4-tert-butyl-2,6-dimethylphenylsulfur trifluoride (Fluolead) have been developed for chemical to date development new fluorinating still ongoing. Electrochemical synthesis has recently attracted much attention from perspective green sustainable chemistry no hazardous required scale-up generally easy. Although electrochemical perfluorination using a nickel anode anhydrous HF well-established manufacture perfluoro-functional partial (selective fluorination) underdeveloped due low nucleophilicity fluoride ions passivation, which interferes with electrolysis. Selective can be commonly achieved aprotic solvents containing provide mostly mono- difluorinated products. Electrolysis conducted at constant potentials slightly higher than first oxidation potential substrate. Constant current electrolysis also effective many cases. Choice combination supporting salt an electrolytic solvent accomplish efficient fluorination. In this Account, we focus on our recent work difluorination application. We briefly explain research background Main factors effects salts electrolytes, solvents, selectivity efficiency discussed. Next, PEG oligomer additives enhancing solvent-free systems poly(HF) ionic liquids well recyclable mediatory described. The desulfurizative monofluorination xanthate gem-difluorination benzothioate dithioacetals mentioned. Regioselective anodic heterocyclic having phenylthio group electroauxiliary heterocycles sulfur other heteroatoms addition, boryl shown good leaving Moreover, electrochemically α,α-difluorinated phenylsulfides phenylselenides illustrated useful photochemical C-H difluoromethylation aromatic heteroaromatic compounds. Finally, Account highlights highly diastereoselective aliphatic open-chain compounds, methods inorganic KF CsF.

Language: Английский

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EnT-Mediated N–S Bond Homolysis of a Bifunctional Reagent Leading to Aliphatic Sulfonyl Fluorides

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(4), P. 2364 - 2374

Published: Jan. 18, 2023

Sulfur(VI) fluoride exchange (SuFEx) gives rise to a plethora of high-valent sulfur linkages; however, the availability (aliphatic) sulfonyl manifolds lag behind, owing limited sources introducing SO2F moiety via classical two-electron approach. Recently, radical-based methodologies have emerged as complementary strategy increase diversity accessible click partners. In this work, synthesis bench-stable sulfamoyl reagent is presented, which may undergo sigma-bond homolysis upon visible-light-induced sensitization form protected β-amino fluorides from alkene feedstocks. Notably, offers an appealing access various building blocks for peptido fluorides, relevant in medicinal chemistry context, well intriguing entry β-ammonium sulfonates and β-sultams, alkenes. Densely functionalized 1,3-sultones were obtained by employing allyl alcohols substrates. Surprisingly, chloride-derived β-imino underwent S-O bond formation ring closure yield rigid cyclopropyl sulfonate ester under SuFEx conditions. Furthermore, engaging thiol-based hydrogen atom donor reaction, reactivity same can be tuned toward direct aliphatic fluorides. Mechanistic experiments indicate energy transfer (EnT)-mediated process. The transient radical adds product occurs either radical-radical coupling or (HAT), respectively.

Language: Английский

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Functional group divergence and the structural basis of acridine photocatalysis revealed by direct decarboxysulfonylation

Chemical Science, Journal Year: 2022, Volume and Issue: 13(14), P. 4170 - 4179

Published: Jan. 1, 2022

The reactivity of the sulfonyl group varies dramatically from nucleophilic sulfinates through chemically robust sulfones to electrophilic halides-a feature that has been used extensively in medicinal chemistry, synthesis, and materials science, especially as bioisosteric replacements structural analogs carboxylic acids other carbonyls. Despite great synthetic potential functional interconversions, a method can convert directly sulfones, halides remained out reach. We report herein development photocatalytic system for first time enables direct decarboxylative conversion sulfinates, well chlorides fluorides one step multicomponent fashion. A mechanistic study prompted by new revealed key features acridine photocatalysts facilitate transformations provided an informative predictive multivariate linear regression model quantitatively relates with activity.

Language: Английский

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Advances in the construction of diverse SuFEx linkers

National Science Review, Journal Year: 2023, Volume and Issue: 10(6)

Published: April 29, 2023

Abstract Sulfur fluoride exchange (SuFEx), a new generation of click chemistry, was first presented by Sharpless, Dong and co-workers in 2014. Owing to the high stability yet efficient reactivity SVI–F bond, SuFEx has found widespread applications organic synthesis, materials science, chemical biology drug discovery. A diverse collection linkers emerged, involving gaseous SO2F2 SOF4 hubs; SOF4-derived iminosulfur oxydifluorides; O-, N- C-attached sulfonyl fluorides sulfonimidoyl fluorides; novel sulfondiimidoyl fluorides. This review summarizes progress these connectors, with an emphasis on analysing advantages disadvantages synthetic strategies connectors based concept, it is expected be beneficial researchers rapidly correctly understand this field, thus inspiring further development chemistry.

Language: Английский

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Fluorochemicals from fluorspar via a phosphate-enabled mechanochemical process that bypasses HF

Science, Journal Year: 2023, Volume and Issue: 381(6655), P. 302 - 306

Published: July 20, 2023

All fluorochemicals—including elemental fluorine and nucleophilic, electrophilic, radical fluorinating reagents—are prepared from hydrogen fluoride (HF). This highly toxic corrosive gas is produced by the reaction of acid-grade fluorspar (>97% CaF 2 ) with sulfuric acid under harsh conditions. The use to produce fluorochemicals via a process that bypasses HF desirable but remains an unsolved problem because prohibitive insolubility . Inspired calcium phosphate biomineralization, we herein disclose protocol treating dipotassium (K HPO 4 mechanochemical affords solid composed crystalline K 3 (HPO )F 2− x Ca y (PO F) b , which found suitable for forging sulfur-fluorine carbon-fluorine bonds.

Language: Английский

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