- New types of asymmetrical bromonium salts [RF(R F′)Br]Y where RF and/or RF′ represent perfluorinated aryl, alkenyl, and alkynyl groups
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A series of previously unknown asymmetrical fluorinated bis(aryl)bromonium, alkenyl(aryl)bromonium, and alkynyl(aryl)bromonium salts was prepared by reactions of C6F5BrF2 or 4-CF3C 6H4BrF2 with aryl group transfer reagents Ar′SiF3 (Ar′ = C6F5, 4-FC 6H4, C6H5) or perfluoroorganyl group transfer reagents RF′BF2 (RF = C 6F5, trans-CF3CFCF, C3F 7C≡C) preferentially in weakly coordinating solvents (CCl 3F, CCl2FCClF2, CH2Cl2, CF3CH2CHF2 (PFP), CF3CH 2CF2CH3 (PFB)). The presence of the base MeCN and the influence of the adducts RF′BF2·NCMe (RF = C6F5, CF3C≡C) on reactions aside to bromonium salt formation are discussed. Reactions of C 6F5BrF2 with AlkF′BF 2 in PFP gave mainly C6F5Br and Alk F′F (AlkF′ = C6F13, C6F13CH2CH2), presumably, deriving from the unstable salts [C6F5(AlkF′)Br]Y (Y = [AlkF′BF3]-). Prototypical reactivities of selected bromonium salts were investigated with the nucleophile I-and the electrophile H+. [4-CF3C 6H4(C6F5)Br][BF4] showed the conversion into 4-CF3C6H4Br and C 6F5I when reacted with [Bu4N]I in MeCN. Perfluoroalkynylbromonium salts [CnF2n+1C≡C(R F)Br][BF4] slowly added HF when dissolved in aHF and formed [Z-CnF2n+1CFCH(RF)Br][BF4].
- Frohn, Hermann-Josef,Giesen, Matthias,Bardin, Vadim V.
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experimental part
p. 969 - 974
(2010/12/19)
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- Bis(perfluoroorganyl)bromonium salts [(RF)2Br]Y (RF = aryl, alkenyl, and alkynyl)
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Bromonium salts [(RF)2Br]Y with perfluorinated groups RFC6F5, CF3CFCF, C 2F5CFCF, and CF3C≡C were isolated from reactions of BrF3 with RFBF2 in weakly coordinating solvents (wcs) like CF3CH2CHF2 (PFP) or CF3CH2CF2CH3 (PFB) in 30-90% yields. C6F5BF2 formed independent of the stoichiometry only [(C6F5)2Br][BF 4]. 1:2 reactions of BrF3 and silanes C6F 5SiY3 (Y = F, Me) ended with different products - C 6F5BrF2 or [(C6F5) 2Br][SiF5] - as pure individuals, depending on Y and on the reaction temperature (Y = F). With C6F5SiF3 at ≥-30 °C [(C6F5)2Br][SiF5] resulted in 92% yield whereas the reaction with less Lewis acidic C 6F5SiMe3 only led to C6F 5BrF2 (58%). The interaction of K[C6F 5BF3] with BrF3 or [BrF2][SbF 6] in anhydrous HF gave [(C6F5) 2Br][SbF6]. Attempts to obtain a bis(perfluoroalkyl) bromonium salt by reactions of C6F13BF2 with BrF3 or of K[C6F13BF3] with [BrF2][SbF6] failed. The 3:2 reactions of BrF3 with (C6F5)3B in CH2Cl2 gave [(C6F5)2Br][(C6F 5)nBF4-n] salts (n = 0-3). The mixture of anions could be converted to pure [BF4]- salts by treatment with BF3·base.
- Frohn, Hermann-Josef,Giesen, Matthias,Welting, Dirk,Bardin, Vadim V.
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experimental part
p. 922 - 932
(2010/10/03)
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- A widely varying range of products in reactions of C6F5BrF2, C6F5IF2, and C6F5IF4 with Lewis acids of different strength
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The relative fluoride donor ability: C6F5BrF2 > C6F5IF2 > C6F5IF4 was outlined from reactions with Lewis acids of graduated strength in different solvents.
- Frohn, Hermann-Josef,Bailly, Frank,Welting, Dirk,Bardin, Vadim V.
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experimental part
p. 301 - 307
(2009/12/04)
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- Electrophilic oxygenation with XeF2 - H2O in hydrogen fluoride, Part 2. Electrophilic oxygenation of pentafluorobenzene derivatives C6F5X
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Electrophilic oxygenation of polyfluorobenzenes C6F5X (X = F, Cl, Br, H, CF3, NH3+, NMe3+, OH and OCH2CF3) with XeF2 and H2O in HF leads to the formation of polyfluorinated 1,4-cyclohexadienones. Pentafluoroiodobenzene is converted into C6F5IF2 and C6F5IF4, whereas [C6F5N2]+ [NbF6]- is unreactive towards this new type of electrophilic oxygenation.
- Frohn,Bardin
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p. 1015 - 1021
(2007/10/03)
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- (Heptafluoro-1,4-cyclohexadien-1-yl)xenon(II) and (Nonafluorocyclohexen-1-yl)xenon(II) Hexafluoroarsenates: Synthesis, Spectroscopic Characterization and Reactivity of the First Alkenylxenon(II) Compounds
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The first alkenylxenon(II) compounds: (heptafluoro-1,4-cyclohexadien-1-yl)xenon(II) hexafluoroarsenate +-1,4-C6F7>- and (nonafluorocyclohexen-1-yl)xenon(II) hexafluoroarsenate +-C6F9>- were
- Frohn, Hermann,Bardin, Vadim V.
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p. 1072 - 1074
(2007/10/02)
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- BF3-Catalyzed Fluorine Addition to Fluoro-Substituted Benzene Derivatives Using Xenon Difluoride
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BF3-catalyzed room-temperature reaction of xenon difluoride with pentafluoro-substituted benzene derivatives resulted in 1,4- and 1,2-fluorine addition with regiospecificity depending on the substituent.Reaction with 1-substituted (H, Cl, Br, C6F5) pentafluorobenzene resulted in the formation of 1-substituted heptafluorocyclohexa-1,4-dienes, and reactions with n-alkoxy-substituted pentafluorobenzenes resulted in two types of 1,4-adducts, while reaction with isopropoxypentafluorobenzene resulted in the formation of hexafluorocyclohexa-2,5-dien-1-one and hexafluorocyclohexa-2,4-dien-1-one.
- Stavber, Stojan,Zupan, Marko
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p. 300 - 302
(2007/10/02)
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