- Unexpected reactivity of cyclic perfluorinated iodanes with electrophiles
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We have found that cyclic perfluorinated iodanes react with electrophiles (E+ = Br, Cl, F, I) to afford perfluorinated E-RF compounds. This reactivity is unexpected since cyclic perfluorinated iodanes are considered as electrophilic reagents that normally react with nucleophiles (e.g. Nu- = SR, OR) to afford Nu-RF products. The utility of this new transformation is demonstrated for a [18F]CF3CF2-containing compound which was prepared from [18F]XeF2 obtained from cyclotron produced [18F]fluoride.
- Gruber, Stefan,Ametamey, Simon M.,Schibli, Roger
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supporting information
p. 8999 - 9002
(2018/08/21)
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- Addition of trifluoromethanes to fluoroolefins and isomerization of monohaloperfluoro alkanes
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A process for the Lewis acid catalyzed addition of trifluoromethanes across the carbon-carbon double bond of fluoroolefins is disclosed. A process for isomerization of monohaloperfluoro alkanes is also disclosed.
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- Addition of some unreactive fluoroalkanes to tetrafluoroethylene.: Direct catalytic synthesis of F-butene-2
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Condensation of trifluoromethanes, CF3X (X=H, Cl, Br, I), with tetrafluorethylene to form the corresponding F-n-propyl adducts have been carried out with aluminum chlorofluoride as catalyst. Yields of C3F7I and C3F7Br are especially good, making these useful perfluoropropyl intermediates readily available. Details of the reactions, especially the presence of low percentages of perfluoroisopropyl iodide and bromide in the products, are accounted for by proposed mechanisms involving halonium intermediates. Longer-chain primary iodides can also be added to tetrafluoroethylene, but the final products are predominantly fluoroolefins, with pentafluoroethyl iodide as a byproduct. In the case of the addition of C2F5I to tetrafluoroethylene, conditions for an efficient, low temperature dimerization of terafluoroethylene to F-butene-2 catalyzed by a combination of C2F5I/aluminum chlorofluoride have been defined. Evidence for an unusual transfer of I+ from the iodonium derivative of F-butene-2 to tetrafluoroethylene is presented.
- Petrov, Viacheslav A.,Krespan, Carl G.
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p. 199 - 204
(2007/10/03)
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- BROMINATION OF FLUOROALKENES PART 5.-KINETICS OF FORWARD AND REVERSE REACTIONS IN THE SYSTEM Br2+i-C3F7HHBr+i-C3F7Br
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The kinetics of the forward and reverse reactions in the gas-phase system have been studied.The slow steps for the forward and reverse reactions, respectively, are .The Arrhenius parameters obtained, for the range 421-534 deg C, are .The competitive brominations of mixtures of i-C3F7H+C2F5H and i-C3F7H+n-C3F7H have been studied over the ranges 249-430 and 220-402 deg C, respectively.Each system yielded Arrhenius parameters for reaction (2) which are in excellent agreement with those given above.The results lead to the following bond dissociation energies at 298 K: Attempts were made to measure D using competitive photobromination and photochlorination.However, (CF3)3C-H is so unreactive that only the approximate result D ca. 456 kJ mol-1 was obtained.The trends in C-H and C-Br bond dissociation energies are compared in alkanes, fluoroalkanes and the corresponding bromides.
- Evans, Brian S.,Weeks, Ian,Whittle, Eric
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p. 1471 - 1482
(2007/10/02)
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- Synthesis of Perfluoroalkyl Trifluoromethanesulfonates from Perfluoroalkyl Halides. Substitutive Electrophilic Dehalogenation with Chlorine(I) and Bromine(I) Trifluoromethanesulfonates
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The reactions of chlorine(I) and bromine(I) trifluoromethanesulfonates with a variety of perfluoroalkyl halides are reported.The reactions form Br2, Cl2, or BrCl and the corresponding trifluoromethanesulfonate derivatives of the alkyls in good yields.Twelve new esters are reported and characterized.An SEi-type mechanism for the reactions is proposed with complete retention of configuration by the alkyl on substitution.
- Katsuhara, Yutaka,DesMarteau, Darryl D.
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p. 2681 - 2686
(2007/10/02)
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