- Diazotization of pentafluoroaniline by means of anion-catalyzed phase transfer catalysis in a hydrophobic organic solvent
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Anion-catalyzed phase-transfer catalysis was successfully applied to diazotization of pentafluoroaniline in a dichloromethane-aqueous sulfuric acid two-phase system.The resulting diazonium group was coupled in situ with anisole, 1-methoxynaphthalene, and mesitylene, and replaced in situ with bromo, hydryl, and phenyl substituents under a two-phase condition.
- Iwamoto, Hidetoshi,Sonoda, Takaaki,Kobayashi, Hiroshi
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Read Online
- Thermal electron attachment to C6F5X and C6H5X (X - I, Br, Cl, and F)
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Rate constants have been measured for thermal electron attachment to C6F5X (X = I, Br, Cl, F, and H) and C6H5X (X = I, Br, Cl, and F) at room temperature in N2 buffer gas (1-100 Torr) using the pulse-radiolysis microwave cavity method.For all the compounds studied, the rate constants are of the two-body type.Unexpectedly, the values for C6F5X except C6F5H are all the same (ca. 2 x 10-7 cm3 molecule-1 s-1), which are higher than most of the previous values, while that for C6F5H, measured in Xe and Ar buffer gases, is very low (7 x 10-12 cm3 molecule-1 s-1).For C6H5X, the value decreases dramatically with varying X from I to Br to Cl as 1.0 x 10-8 to 6.5 x 10-12 to 3 x 10-14 cm3 molecule-1 s-1, and that for C6H5F must be much lower than 10-13 cm3 molecule-1 s-1.These results for the magnitude of the rate constant are rationalized by the variation in the energy of a transient negative-ion state of each molecule, which results from a combination of the electron affinities of constituents (halogen atom X and C6F5 radical) and the strength of the C6F5-X (or C6H5-X) bond.
- Shimamori, Hiroshi,Tatsumi, Yoshitsugu,Suanagawa, Takeyoshi
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Read Online
- One-pot route to X-perfluoroarenes (X = Br, I) based on FeIII-assisted C-F functionalization and utilization of these arenes as building blocks for crystal engineering involving halogen bonding
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Perfluorinated arenes (benzeneF derivatives, diphenylF, naphthaleneF) were converted into X-perfluoroarenes (X = Br, I) via the developed one-pot protocol based on [Fe(acetylacetonate)3]-assisted C-F functionalization. The syntheses proceed under mild conditions and employ readily available perfluorinated arenes, which are treated with EtMgBr followed by addition of X2/[Fe(acetylacetonate)3] (0.8 mol %); yields range from good to moderate. The σ-hole donor properties of the obtained mono- and di-X-perfluoroarenes and the significance of these species for halogen-bonding-based crystal engineering was illustrated in a series of postsynthetic experiments, all supported by density functional theory (DFT) energy calculations, molecular electrostatic potential (MEP) surface analysis, and the quantum theory of atoms in molecules (QTAIM). These include (i) a solid-state X-ray diffraction study of X-perfluoroarene self-association (dimerization) via iodine σ-hole - electron belt interactions (three X-ray structures) and (ii) verification of X-perfluoroarene σ-hole donor abilities by their interactions with iodides acting as external σ-hole acceptors (five X-ray structures); a Hirshfeld surface analysis was performed for all eight structures.
- Baykov, Sergey V.,Eliseeva, Anastasiya A.,Frontera, Antonio,Galmés, Bartomeu,Kukushkin, Vadim Yu.,Rozhkov, Anton V.
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p. 5908 - 5921
(2020/10/13)
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- Preparation method of bromopentafluorobenzene
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The invention relates to a preparation method of bromopentafluorobenzene, and belongs to the technical field of fine chemical synthesis. The method comprises the following steps: preparing bromine chloride through chlorine and bromine in an organic solvent; ensuring that penta fluoro benzene serving as a raw material is in reaction with the bromine chloride in an organic solvent under the existence of a Lewis acid catalyst, so as to form the bromopentafluorobenzene. The method has the advantages that the raw materials are available, the cost is low, unit consumption of bromine is effectively reduced, two bromine in bromine molecule can be sufficiently utilized, the production cost is reduced, and the method has a significance for realizing the scale production of the bromopentafluorobenzene.
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Paragraph 0024-0037
(2019/04/06)
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- 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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- Transition-metal-free decarboxylative bromination of aromatic carboxylic acids
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Methods for the conversion of aliphatic acids to alkyl halides have progressed significantly over the past century, however, the analogous decarboxylative bromination of aromatic acids has remained a longstanding challenge. The development of efficient methods for the synthesis of aryl bromides is of great importance as they are versatile reagents in synthesis and are present in many functional molecules. Herein we report a transition metal-free decarboxylative bromination of aromatic acids. The reaction is applicable to many electron-rich aromatic and heteroaromatic acids which have previously proved poor substrates for Hunsdiecker-type reactions. In addition, our preliminary mechanistic study suggests that radical intermediates are not involved in this reaction, which is in contrast to classical Hunsdiecker-type reactivity. Overall, the process demonstrates a useful method for producing valuable reagents from inexpensive and abundant starting materials.
- Quibell, Jacob M.,Perry, Gregory J. P.,Cannas, Diego M.,Larrosa, Igor
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p. 3860 - 3865
(2018/04/26)
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- Method for preparing 2,3,4,5,6-pentafluorophenol
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The invention discloses a method for preparing 2,3,4,5,6-pentafluorophenol. The method comprises the following step of in water, performing an oxidation reaction on 2,3,4,5,6-pentafluoro phenylboronic acid as shown in the formula (VI) and hydrogen peroxide, thereby obtaining 2,3,4,5,6-pentafluorophenol as shown in the formula (VII). According to the method, an oxidation reaction is implemented in the water, so that the method is low in cost, and environmental-friendly; and besides, the method is high in reaction yield and purity and relatively applicable to industrial production.
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Paragraph 0096; 0097
(2017/08/29)
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- PROCESS FOR THE PREPARATION OF ORGANIC BROMIDES
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The present invention provides a process for the preparation of organic bromides, by a radical bromodecarboxylation of carboxylic acids with a bromoisocyanurate.
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Paragraph 00139
(2017/07/28)
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- Unexpected distinction in reactivity of pentafluorobenzenesulfonyl halides toward organolithiums and organomagnesium halides
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C6F5SO2Cl reacts with organolithiums and organomagnesium halides RM (R = Me, Bu, Ph; M = Li, MgX) to give mainly C6F5H and C6F5Cl. C6F5SO2Br and
- Bardin, Vadim V.,Maksimov, Alexander M.
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p. 731 - 737
(2017/10/16)
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- Mechanical device for preparing bromopentafluorobenzene
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The invention discloses a mechanical device for preparing bromopentafluorobenzene. The mechanical device for preparing bromopentafluorobenzene belongs to the field of fine chemical production machinery. The mechanical device comprises a high-pressure reaction kettle (1), a chemical reaction kettle (2) and a reduced-pressure distiller (3). The mechanical device is characterized in that a pentafluorobenzoic acid inlet (4), a water inlet (5) and a waste liquid outlet (6) are arranged on the high-pressure reaction kettle (1); a first material slurry pump and pipeline (7) is arranged between the high-pressure reaction kettle (1) and the chemical reaction kettle (2); a bromine water inlet (8), a sodium sulfate aqueous solution inlet (9) and a waste liquid outlet (10) are arranged on the chemical reaction kettle (2); a second material slurry pump and pipeline (11) is arranged between the chemical reaction kettle (2) and the reduced-pressure distiller (3); a steam outlet (12) is arranged on the reduced-pressure distiller (3); and a final-product outlet (13) is arranged on the reduced-pressure distiller (3).
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Paragraph 0010-0012
(2017/03/23)
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- Mild bromination of unreactive aromatic compounds
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N,N,N', N'-Tetrabromobenzene-1,3-disulfonamide and poly(N, N'-dibromo-N-ethylene-benzene-1,3-disulfonamide) in concentrated H 2SO4 can be used as efficient reagents for the mild bromination of unreactive arenes at room temperature, under solvent-free conditions, in good yields.
- Ghorbani-Vaghei, Ramin,Shahbazi, Hajar,Veisi, Hojat
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experimental part
p. 2325 - 2327
(2012/07/14)
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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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- 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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body text
p. 969 - 974
(2010/12/19)
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- Superelectrophilic bromination of deactivated aromatic rings with tribromoisocyanuric acid-an experimental and DFT study
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The reaction of deactivated arenes with tribromoisocyanuric acid (TBCA) in 98% H2SO4 produced bromoarenes in good yields. The acidity of the medium controls the strength of the brominating agent and the amount of polybrominated products. DFT calculations at B3LYP/6-311++G** level showed that the protonated TBCA (a superelectrophilic species) can easily transfer Br+ to deactivated arenes, in order to decrease internal charge-charge repulsion.
- de Almeida, Leonardo S.,Esteves, Pierre M.,de Mattos, Marcio C.S.
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experimental part
p. 3001 - 3004
(2009/09/28)
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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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- Organofluorine sulfur-containing compounds: V. Joint pyrolysis with chlorine or bromine of polyfluoroarenethioles, polyfluorohetarenethioles, and their derivatives
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Joint pyrolysis with chlorine and bromine of polyfluoroarenethiols, -hetarenethiols, and their derivatives at 300-650°C furnished polyfluorocompounds containing chlorine and bromine. 2005 Pleiades Publishing, Inc.
- Platonov,Maksimov,Dvornikova,Nikul'shin
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p. 1647 - 1653
(2007/10/03)
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- N-halosuccinimide/BF3-H2O, efficient electrophilic halogenating systems for aromatics
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N-Halosuccinimides (NXS, 1) are efficiently activated in trifluoromethanesulfonic acid and BF3-H2O, allowing the halogenations of deactivated aromatics. Because BF3-H2O is more economic, easy to prepare, nonoxidizing, and offers sufficiently high acidity (-H0 ≈ 12, only slightly lower than that of trifluoromethanesulfonic acid), an efficient new electrophilic reagent combination of NXS/BF3-H2O has been developed. DFT calculations at the B3LYP/6-311++G**//B3LYP/6-31G* level suggest that protonated N-halosuccinimides undergo further protosolvation at higher acidities to reactive superelectrophilic species capable either in the transfer of X+ from the protonated forms of NXS to the aromatic substrate or in forming a highly reactive and solvated X+ which would readily react with the aromatic substrates. Structural aspects of the BF 3-H2O complex have also been investigated.
- Prakash, G. K. Surya,Mathew, Thomas,Hoole, Dushyanthi,Esteves, Pierre M.,Wang, Qi,Rasul, Golam,Olah, George A.
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p. 15770 - 15776
(2007/10/03)
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- Reactions of methyl(pentafluorophenyl)- and methyl(pentafluorophenyl)phenylsilanes with electrophiles. A convenient preparative route to halogeno(methyl)pentafluorophenylsilanes C6F5SiMe2X and C6F5SiMeX2 (X=F, Cl and Br)
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Halogeno(methyl)pentafluorophenylsilanes C6F5SiMenX3-n (n=1, 2) (X=F, Cl, Br) were prepared in good yields from the corresponding phenylsilanes C6F5SiMenPh3-n by reactions with the electrophiles aHF, HCl-AlCl3, Br2-AlBr3 or AlX3 (X=Cl, Br) halogenated hydrocarbons. Additionally, reactions of C6F5SiMe3 and (C6F5)2SiMe2 with selected electrophiles were studied.
- Frohn,Lewin,Bardin
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p. 255 - 263
(2007/10/03)
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- Conversion of hexafluorobenzene to bromopentafluorobenzene
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A method for producing tetrakis (pentafluorophenyl) borates is described. Hexafluorobenzene is converted to bromopentafluorobenzene which may be isolated and then reacted with an alkyl lithium to produce pentafluorophenyl lithium which in turn is reacted directly with an appropriate reagent to produce the desired borate.
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- Reactivity of Negative Ions with Trifluoromethyl Halides
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The kinetics of the reactions of selected anions (A(-)) with the trifluoromethyl halides CF3X (X = F, Cl, Br, I) in the gas phase were measured at 300 K.Reaction rate constants and product branching fractions were determined using a selected ion flow tube (SIFT) instrument.The chosen anions were C5F5N(-), o-, m-, and p-CF3C6H4CN(-), C6F5Br(-), C6F5Cl(-), C6F5CF3(-), C6F5COCH3(-), Fe(-), FeCO(-), SF6(-), SO(-), SO2(-), NO(-), NO2(-), and NO3(-).The reactivity of these systems varies from unreactive to collisional, and a variety of reaction types was found.The results of our present and previous measurements on A(-) + CF3X reactions show that, in cases where nondissociative electron transfer (NDET) is energetically allowed, the total reactivity tends to be high, approaching collisional.This suggests that reactivity in these cases is initiated and controlled by electron transfer from the anion.In addition, association reactions tend to be preempted when NDET is energetically allowed.A few exceptions to these tendencies were found and are discussed.
- Morris, Robert A.,Viggiano, A. A.,Miller, Thomas M.,Seeley, John V.,Arnold, Susan T.,et al.
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p. 10641 - 10645
(2007/10/03)
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- Fluorination of tetrafluorobenzenes C6HF4R with XeF2
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Replacement of hydrogen by fluorine and addition of fluorine atoms to the aromatic ring were found in the reaction of XeF2 with 1-R-2,3,4,5-tetrafluorobenzene (R = H, F, Br, NO2) or 1-R-2,3,4,6-tetrafluorobenzene (R = H, CF3) in HF or CH2Cl2-BF3·OEt2. Only fluorine addition took place in the case of 1-R-2,3,5,6-tetrafluorobenzenes (R = H, Br, CF3) or 1-Br-2,3,4,6-tetrafluorobenzene. The role of cation radicals as reactive intermediates is discusseed.
- Bardin,Shchegoleva,Frohn
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p. 153 - 159
(2007/10/03)
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- A convenient preparation of pentafluorophenyl( fluoro) silanes: Reactivity of pentafluorophenyltrifluorosilane
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Pentafluorophenyl(fluoro)silanes (C6F5)nSiF4-n (n = 1, 2) were prepared from the corresponding ethoxysilanes by sequential chlorodeethoxylation with SOCl2 and fluoridation of chlorosilanes with SbF3. The conversion of C6F5Si(OEt)3 and C6F5SiCl3 into C6F5SiF3 with anhydrous HF was described. Some reactions of C6F5SiF3 with electrophiles and nucleophiles were studied.
- Frohn,Giesen,Klose,Lewin,Bardin
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p. 155 - 164
(2007/10/02)
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- Preparation, NMR spectra and reactivity of pentafluorophenyltetrafluorosilicates M+-
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Pentafluorophenyltetrafluorosilicates M+ - were obtained from pentafluorophenyltrifluorosilane C6F5SiF3 and ionic fluorides MF (M=K, Cs, Me4N) in anhydrous MeCN or diglyme.The reactivity of M+ - toward electrophiles was studied.Keywords: Pentafluorophenyl; Fluorosilicate anion; Desilylation
- Frohn, H. J.,Bardin, V. V.
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p. 155 - 160
(2007/10/02)
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- Dynamics of endoergic substitution reactions. I. Br+chlorinated aromatic compounds
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The endoergic substitution reactions Br + R-Cl -> Cl + R-Br (R = o-, m-, andp-CH3C6H4, C6H5, C6F5; ΔH0 ca. 15 kcal/mol) have been studied using the crossed molecular beams method in the collision energy (Ec ) range 2-35 kcal/mol.The CH3C6H4Br and C6F5Br products were found to be mostly forward scattered with respect to the incident Br beam indicating that the lifetimes of the Br-R-Cl collision complexes are short compared to their rotational periods.The product translational energy distributions and excitation functions for these reactions are well reproduced by statistical calculations that assume that only a few vibrational modes in the collision complexes participate in intramolecular energy redistribution prior to Cl elimination.Ring substituents are found to affect both the extent of energy redistribution in the complexes and the probability of Br addition.For example, no substitution product was observed with m-CH3C6H4Cl or C6H5Cl.The relative magnitudes of the cross sections are explained in terms of possible features of the potential energy surfaces along their reaction coordinates.
- Robinson, Gary N.,Continetti, Robert E.,Lee, Yuan T.
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p. 6226 - 6237
(2007/10/02)
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- AROMATIC FLUORINE DERIVATIVES. XCI. REGIOSPECIFIC FLUORINATION OF POLYFLUORINATED AROMATIC COMPOUNDS BY SALTS OF THE DIFLUOROBROMONIUM CATION BrF2+
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The reaction of polyfluorinated aromatic compounds with difluorobromium tetrafluoroborate BrF2+*BF4- leads to the products from regiospecific fluorination.Polyfluorinated derivatives of benzene, toluene, and naphthalene are fluorinated to form 1,4-cyclohexadienes, whereas pentafluoropyridine and 3-chlorotetrafluoropyridine are converted into the corresponding 1-aza-1,3-cyclohexadienes.
- Bardin, V. V.,Furin G. G.,Yakobson, G. G.
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p. 879 - 884
(2007/10/02)
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- Organothallium compounds. VI. Reactions of bromobis(pentafluorophenyl)thallium(III) with main group elements
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Bromobis(pentafluorophenyl)thallium(IlI) reacts with many main group elements on heating in the absence of a solvent to give pentafluorophenyl derivatsves of these elements. The compounds C6F5M (M = Cl, Br, or I), (C6F5)2M (M = Zn, Cd, Hg, S, Se or Te), (C6F5)3M (M = In, P, As, or Sb), and (C6F5)M (M = Ge or Sn) have been prepared by this method. Substantial decomposition of (C6F5)2TlBr occurs on reaction with aluminium, gallium, lead and bismuth, but pcntafluorophenyl derivatives of these elements are not obtained.
- Deacon,Parrott
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p. 287 - 295
(2008/10/08)
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