Fluorine atom source

Thus, AgF3 is a more effective fluorine atom source than molecular fluorine, with which xenon does not react at ordinary temperatures and pressures in the absence of catalyst. It is more surprising that even AgFj is able to oxidize xenon since Ag(III) in the electron rich environment of an anion must be less electronegative than the Ag(III) in AgF3 ... 

The O2F indeed must rival KrF2 fluorine atom source. It was not able to excite Pd however, and attempts to obtain the previously claimed O Pd Fg, all gave O Pd Fs, which is the probable formulation for the supposed Pd salt. 

Either [XeF]+ or [XejFj], in capturing an electron, will produce the readily dissociable XeF radical. This radical must be an effective fluorine atom source. Since the reduction product, xenon, is relatively inert, the... 

Although l -NiF3 as a dry solid, is unable to oxidize xenon it does so when it has been exposed to HF vapor ( 100 Torr). This reaction (to produce XeF2), unlike the formation of Xep2 from xenon and F2, does proceed in the dark. The IJ-NiFs therefore behaves much more like a fluorine atom source. It is of interest that studies " in the early 1960s showed that the interaction of xenon with F2 in nickel vessels occurred via a NiFx intermediate. The red-brown nickel fluoride remaining from the /J-NiFs reduction by xenon may have a composition NirFs. It possesses a distinctive (but unknown) structure see Table 4. 

Thus, AgFj is a more effective fluorine atom source than molecular F2, with which Xe does not interact, in the absence of catalysts, under ordinary pressures and temperatures. It was, however, more surprising to find that even anionic Ag(lII) will oxidize xenon spontaneously according to... 

Fig. 2.12 Results of crossed beam experiment with doubie-stage discharge fluorine atom source, but either time or puise width of both is not controiiabie, and the two discharges are in the same space...

The velocity selected fluorine atom source was the workhorse for much of the work done in this laboratory, but recent developments in seeded supersonic beam technology have led to much more efficient means of halogen atom beam production. The... 

Faubel M, Martinez-Haya B, Rusin L Y, Tappe U and Toennies J P 1996 An intense fluorine atom beam source J. Rhys. D Appl. Rhys. 29 1885-93... 

McFeely and co-workers used soft x-ray photoelectron spectroscopy (SXPS) to measure the changes in binding energies of Si(2p) levels after slight exposure to fluorine atoms via dissociative chemisoriDtion of XeF2 [39]. Using synclirotron radiation at 130 eV as the source enabled extreme surface sensitivity. Since this level is split into a... 

The effectiveness of various sources of fluoride ion in the displacement of the trifluoromethanesulfonic group has been demonstrated while introducing a fluorine atom into the five-membered carbocyclic ring of a prostaglandin precursor Treat tnent of the corresponding triflyl derivative with potassium fluoride in acetonitrile or with cesium fluonde in refluxing diinethylformamide or hexamethylphosphoric... 

Despite the body of evidence in favor of the Mayo mechanism, the formation of diphenylcyclobutanes (90, 91) must still be accounted for. It is possible that they arise via the 1,4-diradical 94 and it is also conceivable that this diradical is an intermediate in the formation of the Diels-Alder adduct 95 (Scheme 3.64) and could provide a second (minor) source of initiation. Direct initiation by diradicals is suggested in the thermal polymerization of 2,3,4,5,6-pentafluorostyrene where transfer of a fluorine atom from Diels-Alder dimer to monomer seems highly unlikely (high C-F bond strength) and for derivatives which cannot form a Diels-Alder adduct. 

The DMS method has not been employed yet for the generation of 117 and 123, since the dibromocarbene adducts of norbomadiene and norbornene rearrange under the usual conditions for the preparation [89]. However, they could be synthesized at -60 °C by taking advantage of tetrabromomethane and methyllithium as a source of the carbene [90] and could prove stable enough to serve as precursors of 117 and 123. On the other hand, the adducts of bromofluorocarbene to norborna-diene and norbornene having the fluorine atom in a cis-orientation should be isol-able at room temperature and hence be usable as stable precursors of 117 and 123. These variations ofthe DMS method were published on the occasion ofthe preparation of cycloadducts of l-oxa-2,3-cyclohexadiene (351) (Section 6.3.6) [35, 91], 1,2,4-cyclohexatriene (162) and 3d2-lJ-f-naphthalene (221) (Section 6.3.4) [35, 92],... 

Anodic nucleophilic functionalization of an a-carbon turned out to be particularly efficient for the fluorination of organic sulfides. The introduction of one or two fluorine atoms at the a-carbon was reported in several papers for sulfides bearing EWGs = CN, COMe, COPh, CF3, COzEt, CONEt2, PO(OEt)2) (Scheme 18) [75-78], Two systems are mainly used as the supporting electrolyte and fluorine source at a time namely, EtsN-SHF and Etr NF. 

The oxidative metabolism leads to the formation of reactive species (epoxides, quinone-imines, etc.), which can be a source of toxicity. Consequently, slowing down or limiting these oxidations is an important second target in medicinal chemistry. Thus, the metabolism of halothan (the first modern general anaesthetic) provides hepatotoxic metabolites inducing an important rate of hepatitis the oxidation of the non-fluorinated carbon generates trifluoroacetyl chloride. The latter can react with proteins and lead to immunotoxic adducts [54], The replacement of bromine or chlorine atoms by additional fluorine atoms has led to new families of compounds, preferentially excreted by pulmonary way. These molecules undergo only a very weak metabolism rate (1-3%) [54,55]. 

An amine with labile fluorine atoms, A -(l,l,2,3,3,3-hexafluoropropyl)diethylamine, generated in situ by the interaction of perfluoroprop-l-ene and diethylamine, was found to work well as a source of fluorine in the reactions of 1,3-dithiolanes with 1,3-dibromo-5,5-dimethylhydan-toin or A -iodosuccinimide. The reactions run in dichloromethane at — 78 to — 20 C give gem-difluorides in 50-70% yield.76... 

HF Py serves as a source for fluorine atoms in electrochemical reactions as well38. An electron or two (depending on the applied voltage) are pulled out near the anode and the resulting carbocation reacts immediately with the fluoride anion (equation 21). 

Xenon difluoride is able to transfer a fluorine atom to organic molecules without any catalyst, with very reactive organic molecules or at higher temperatures or under photochemical conditions. However, reactions are usually performed in the presence of various types of catalysts, but in some cases a new xenon compound FXeYL is formed (Scheme 1), which can be a source of fluorine atoms, or of a YL or Y group for transfer to an organic molecule. On the other hand, decomposition of the FXeYL molecule results in the desired fluorinated products (FYL, FL or FY). Fluoro-substituted xenon derivatives (FXeYL) can also be further transformed to disubstituted derivatives, which are usually less stable at room temperature, but can also be excellent sources of YL, Y or L groups for transfer to various organic molecules. The next possibility is that xenon difluoride converts an... 

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