Hypofluorous acid and acetonitrile: the taming of a reagent

Appelman, Evan H.; Dunkelberg, O.; Kol, Moshe

doi:10.1016/s0022-1139(00)81103-3

Cited by 25 publications

(27 citation statements)

References 29 publications

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“…[13,14] We did not have any luck with rigorously dried acetonitrile, but to our surprise wet CH 3 CN produced an oxidizing solution which was stable for few hours at room temperature. [17] An X-ray analysis of the complex was also taken at low temperature, revealing a hydrogen bond between the nitrogen atom of the acetonitrile and the hydrogen of the hypofluorous acid. After some additional research, we reached the conclusion that the oxidant is a complex between the known, but extremely unstable (and therefore not very useful) HOF, [16] and acetonitrile.…”

Section: General Backgroundmentioning

confidence: 99%

Elemental Fluorine and HOF·CH₃CN in Service of General Organic Chemistry

Rozen

2005

Eur J Org Chem

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At present, HOF·CH3CN complex is the best oxygen transfer agent that chemistry has to offer. It is readily made by passing dilute fluorine through aqueous acetonitrile and does not require any isolation or purification. It is stable in aqueous acetonitrile solution for a few hours at room temperature, providing ample opportunities for various reactions. Epoxidation of regular olefins as well as of very electron‐depleted ones proceeds smoothly. HOF·CH3CN transfer oxygen also to heteroatoms, especially sulfur and nitrogen. Even very electron‐depleted sulfides such as RfSAr that are very difficult to oxidize, are converted into the respective sulfones in a matter of minutes. On the other hand, since the reaction conditions are very mild, the reagent can oxidize various thiophenes and amino acids to the corresponding S,S‐dioxides and α‐nitro acid derivatives. HOF·CH3CN was also instrumental in ending the 50 years quest for making the elusive 1,10‐phenanthroline N,N‐dioxide and for the novel transformation of azides to nitro derivatives. The use of BrF3 for making symmetric esters and of tBuOF as an electrophilic tert‐butoxylation agent is also mentioned. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

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Section: General Backgroundmentioning

confidence: 99%

Elemental Fluorine and HOF·CH₃CN in Service of General Organic Chemistry

Rozen

2005

Eur J Org Chem

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“…The latter species was prepared by reacting H180F with unenriched water to make H160180H, followed by oxidation of the labeled hydrogen peroxide to 02 with Ce(IV) (32). A significant improvement over the earlier procedure was the use of H18OF dissolved in acetonitrile that was prepared by fluorinating H180H in CH3CN (33,34). Each absolute spectrum required between 1.2 and 2.1 mmol of enzyme.…”

mentioning

confidence: 99%

Resolution of the reaction sequence during the reduction of O2 by cytochrome oxidase.

Varotsis

Zhang

Appelman

et al. 1993

Proc. Natl. Acad. Sci. U.S.A.

158

148

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Time-resolved resonance Raman spectroscopy has been used to study the reduction of dioxygen by the mitochondrial enzyme, cytochrome oxidase. In agreement with earlier reports, indicates that the peroxy species we detect occurs upon proton uptake from bulk solution; whether this species bridges to CUB remains uncertain. For the ferryl, v(Fe4W+O) is at 790 cm-'. In our time-resolved spectra, the 358 cm-' mode appears prior to the 790 cm-' vibration. By using kinetic parameters deduced from the time-resolved Raman work and from a variety of time-resolved optical studies from other laboratories, we have assigned rate constants to several steps in the linear reaction sequence proposed by G. T. Babcock and M. Wikstrom [(1992) Nature (London) 356, 301-309]. Simulations of this kinetic scheme provide insight into the temporal behavior of key intermediates in the 02 reduction process. A striking aspect of the reaction time course is that rapid 02-binding and trapping chemistry is followed by a progressive slowing down of succeeding steps in the process, which allows the various transient species to build up to concentrations sufficient for their detection by our time-resolved techniques. Our analysis indicates that this behavior reflects a mechanism in which conditions that allow efficient dioxygen bond cleavage are not inherent to the active site but are only established as the reaction proceeds. This catalytic strategy provides an effective means by which to couple the free energy available in late intermediates in the reduction reaction to the proton-pumping function of the enzyme.Cytochrome c oxidase couples the one-electron oxidation of cytochrome c to the four-electron reduction of molecular oxygen and links these electron transfers to proton translocation across the inner mitochondrial membrane (for reviews, see refs. 1-5). The mammalian enzyme contains four redox-active metal centers, two heme a-bound irons and two copper ions. One of the two copper centers, CUA, is the site of ferrous cytochrome c oxidation (6, 7). Electron injection is followed by rapid equilibration of the reducing equivalents between CUA and the low-spin heme center, cytochrome a (2, 8, 9). The latter species serves as the electron-queueing point for controlled electron transfer to the binuclear cytochrome a3/CuB site, where the dioxygen reduction reaction takes place. The regulated electron transfer from cytochrome a forms part of the basis for a model in which events in the binuclear center drive proton translocation (5).Due to the unusual ligand-binding kinetic properties of its binuclear center, cytochrome oxidase is unique among oxygen-activating heme proteins in being susceptible to a detailed kinetic analysis of its reaction with dioxygen. The Gibson-Greenwood flow-flash technique was originally developed for this purpose (10), and the method has since been adapted to a variety of spectroscopic techniques (11-15). Of these, the resonance Raman approach provides considerable structural insight, and it has been applied extens...

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“…Again, then, why is it normally assumed that HFO and [FO] -are much more powerful oxidants than their chlorine-containing counterparts? HFO needs ''taming'' [68] and [FO] -salts cannot even be isolated, whereas the chlorine-containing species are household products. There is a simple answer: elemental fluorine and elemental chlorine are not the products of any experimentally realized redox reaction of interest.…”

Section: Oxygen Monohalides and Hypohalitesmentioning

confidence: 99%

Which halogen is the strongest oxidant? A study with systematics and surprises

2015

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Although it is generally accepted that fluorine is the strongest oxidant among the halogens and so among all of the elements, it has not been explained in the literature why this is the case. In this paper, we ask whether this ''common knowledge'' is indeed true; we also explore various means of determining the oxidation strength of the halogens by considering the energetics of binary halides, hypohalites and dihalogens. In addition, we use Latimer diagrams to evaluate the redox chemistry of these compounds. Ultimately, we find that the conventional wisdom holds and that our investigations have provided a clear understanding of why fluorine is, indeed, the strongest oxidant among the halogens.

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Hypofluorous acid and acetonitrile: the taming of a reagent

Cited by 25 publications

References 29 publications

Elemental Fluorine and HOF·CH₃CN in Service of General Organic Chemistry

Elemental Fluorine and HOF·CH₃CN in Service of General Organic Chemistry

Resolution of the reaction sequence during the reduction of O2 by cytochrome oxidase.

Which halogen is the strongest oxidant? A study with systematics and surprises

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Hypofluorous acid and acetonitrile: the taming of a reagent

Cited by 25 publications

References 29 publications

Elemental Fluorine and HOF·CH3CN in Service of General Organic Chemistry

Elemental Fluorine and HOF·CH3CN in Service of General Organic Chemistry

Resolution of the reaction sequence during the reduction of O2 by cytochrome oxidase.

Which halogen is the strongest oxidant? A study with systematics and surprises

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Product

Resources

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Elemental Fluorine and HOF·CH₃CN in Service of General Organic Chemistry

Elemental Fluorine and HOF·CH₃CN in Service of General Organic Chemistry