Photoredox Activation of SF<sub>6</sub> for Fluorination

McTeague, T. Andrew; Jamison, Timothy F.

doi:10.1002/ange.201608792

Cited by 37 publications

(4 citation statements)

References 31 publications

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“…In another approach to incorporate fluorine into organic molecules using continuous photoredox catalysis, McTeague et al reported the use of gaseous SF 6 for deoxyfluorinations of allylic alcohols (Scheme 155). 716 The reaction system was Prior to irradiation, a small residence time unit was installed for better mixing. Further, a system pressure of 6.9 bar was utilized to increase the solubility of the gaseous fluorine source.…”

Section: •−mentioning

confidence: 99%

The Hitchhiker’s Guide to Flow Chemistry

et al. 2017

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Flow chemistry involves the use of channels or tubing to conduct a reaction in a continuous stream rather than in a flask. Flow equipment provides chemists with unique control over reaction parameters enhancing reactivity or in some cases enabling new reactions. This relatively young technology has received a remarkable amount of attention in the past decade with many reports on what can be done in flow. Until recently, however, the question, "Should we do this in flow?" has merely been an afterthought. This review introduces readers to the basic principles and fundamentals of flow chemistry and critically discusses recent flow chemistry accounts.

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Section: •−mentioning

confidence: 99%

The Hitchhiker’s Guide to Flow Chemistry

et al. 2017

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“…Similar photo-initiated deoxyfluorination reactions involving SF 6 and a range of molecules have been observed in solution, although the mechanistic details are somewhat obscure. [38][39][40][41] We investigated the formation of the photoproduct from NPOO − as a function of the SF 6 partial pressure, which is conveniently assessed from the arrival time of the NPOO − peak; following Blanc's law, 42 the increase in the arrival time should be proportional to the SF 6 partial pressure. The relative yields of the photoproduct and SF -6 are plotted in Fig.…”

Section: Photodetachment and Photochemistry Of 6-hydroxy-2-mentioning

confidence: 99%

Photodetachment and photoreactions of substituted naphthalene anions in a tandem ion mobility spectrometer

et al. 2019

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Substituted naphthalene anions (deprotonated 2-naphthol and 6-hydroxy-2-naphthoic acid) are spectroscopically probed in a tandem drift tube ion mobility spectrometer (IMS). Target anions are selected according to their drift speed through nitrogen buffer gas in the first IMS stage before being exposed to a pulse of tunable light that induces either photodissociation or electron photodetachment, which is conveniently monitored by scavenging the detached electrons with trace SF 6 in the buffer gas. The photodetachment action spectrum of the 2-naphtholate anion exhibits a band system spanning 380-460 nm with a prominent series of peaks spaced by 440 cm −1 , commencing at 458.5 nm, and a set of weaker peaks near the electron detachment threshold corresponding to transitions to dipole-bound states. The two deprotomers of 6-hydroxy-2-naphthoic acid are separated and spectroscopically probed independently. The molecular anion formed from deprotonation of the hydroxy group possesses a photodetachment action spectrum similar to that of the 2-naphtholate anion with an onset at 470 nm and a maximum at 420 nm. Near threshold, photoreaction with SF 6 is observed with displacement of an OH group by an F atom. In contrast, the anion formed from deprotonation of the carboxylic acid group features a photodissociation action spectrum, recorded on the CO 2 loss channel, lying to much shorter wavelength with an onset at 360 nm and maximum photoresponse at 325 nm. † Electronic Supplementary Information (ESI) available: Synthesis procedure for 6-hydroxy-2-methylnaphthoate, calculated vibrational frequencies for the naphtholate anion, photodetachment action spectra of 2-naphtholate anion, 1-naphtholate anion, the two deprotomers of 6-hydroxy-2-naphthoic acid, and deprotonated 6hydroxy-2-methylnaphthoate. See

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“…SF 6 is described in the literature as a highly stable, nonreactive gas, [39][40] and therefore, relatively little remained known about its room-temperature reaction chemistry until fairly recently. [41][42][43][44][45] Owing to its octahedrally-coordinated shell of highly electronegative fluoride ligands, SF 6 is nonpolar, and exhibits high dielectric strength and electron-capture ability that make it a good dielectric insulator. Its spark breakdown under high electric fields, and subsequent gas-phase decomposition products, have been studied in this context, 46 and help to inform our own analysis in considering accessible electrochemical reduction pathways.…”

Section: Resultsmentioning

confidence: 99%

A High-Capacity Lithium–Gas Battery Based on Sulfur Fluoride Conversion

Khurram

Gallant

2018

J. Phys. Chem. C

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Identification of novel redox reactions that combine the prospects of high potential and capacity can contribute new opportunities in the development of advanced batteries with significantly higher energy density than today's state of the art, while advancing current understanding of nonaqueous electrochemical transformations and reaction mechanisms. The immense research efforts directed in recent years towards metal-gas, and in particular lithiumoxygen (Li-O 2 ) batteries, have highlighted the role that gas-to-solid conversion reactions can play in future energy technologies; however, efforts have mainly focused on tailoring the anode (alkali metal) in the metal-gas couple to achieve improved reversibility. Here, in a different approach, we introduce and characterize a new gas cathode reaction that capitalizes on the full change in oxidation state (from +6 to -2) available in redox-active sulfur, based on the cathodic reduction of highly fluorinated sulfur hexafluoride (SF 6 ) in a Li metal battery. In glyme-based electrolyte (0.3 M LiClO 4 in TEGDME), we establish, using quantitative gas and 19 F NMR analysis, that discharge predominantly involves an 8-electron reduction of SF 6 , yielding stoichiometric LiF, as well as Li 2 S and modest amounts of higher-order Li polysulfides. This multi-phase conversion reaction yields capacities of ~3600 mAh g C -1 at moderate rates (30 mA g C -1 ) and potentials up to 2.2 V vs. Li/Li + .In a non-glyme electrolyte, 0.3 M LiClO 4 in DMSO, SF 6 reduction also proceeds readily, yielding higher capacities of ~7800 mAh g C -1 at 30 mA g C -1 . Although not at present rechargeable, the demonstration of, and insights gained, from the primary Li-SF 6 system provides a promising first step for design of novel sulfur conversion chemistries with energy densities that exceed those of today's Li primary batteries, while demonstrating a new design space for nonaqueous gas-to-solid electrochemical reactions.

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Photoredox Activation of SF₆ for Fluorination

Cited by 37 publications

References 31 publications

The Hitchhiker’s Guide to Flow Chemistry

The Hitchhiker’s Guide to Flow Chemistry

Photodetachment and photoreactions of substituted naphthalene anions in a tandem ion mobility spectrometer

A High-Capacity Lithium–Gas Battery Based on Sulfur Fluoride Conversion

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Photoredox Activation of SF6 for Fluorination

Cited by 37 publications

References 31 publications

The Hitchhiker’s Guide to Flow Chemistry

The Hitchhiker’s Guide to Flow Chemistry

Photodetachment and photoreactions of substituted naphthalene anions in a tandem ion mobility spectrometer

A High-Capacity Lithium–Gas Battery Based on Sulfur Fluoride Conversion

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Photoredox Activation of SF₆ for Fluorination