- Reactions of half-sandwich ethene complexes of rhodium(I) toward iodoperfluorocarbons: Perfluoro-alkylation or -arylation of coordinated ethene versus oxidative addition
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Perfluoroalkylation or perfluoroarylation of coordinated ethene takes place when complexes [Rh(η5-Cp*)(η2-C 2H4)2] or [Rh(η5-Cp*) (η2-C2H4)(PR3)] react with IRF, to give complexes [Rh(η5-Cp*)(CH 2CH2RF)(μ-I)]2 (RF = CF(CF3)2(1a), CF(CF3)CF2CF 3 (1b), or C(CF3)3 (1c)) and [(η5-Cp*)IRh(μ-I)2Rh(η5- Cp*)(CH2CH2RF)] (2a-c), or [Rh(η5-Cp*)(CH2CH2R F)I(PR3)] (R = Me, RF = CF(CF3) 2 (3a), C(CF3)3 (3c), C6F 5 (3d); R = Ph, RF = CF(CF3)2 (3a′), CF2C6F5 (3e′)), respectively. Bridge splitting reactions of 1a, 1b, or 1c with phosphines afford complexes [Rh(η5-Cp*)(CH2CH2R F)I(PR3)] (3a, 3a′, 3c; RF = CF(CF 3)2, R = iPr (3a″); RF = CF(CF3)CF2CF3, R = Me (3b), Ph (3b′)). In contrast, oxidative addition dominates over addition to ethene in the reactions of [Rh(η5-Cp*)(η2-C2H 4)(PMe3)] with IRF (RF = CF 2C6F5, nC3F7, nC4F9, CF=CF2) and in the reaction of [Rh(η5-Cp)(η2-C2H 4)(PMe3)] with InC4F9, affording complexes of the type [Rh(η5-C5R 5)(RF)I(PMe3)] (4e-h and 5, respectively). The reaction of [Rh(η5-Cp*)(η2-C 2H4)(PR3)] with ICF(CF3)CF 2CF3 gives a mixture of cis- and trans-octafluoro-2-butene as the main fluoroorganic reaction product. Evidence for the intermediacy of RF- anions in these reactions has been obtained. 3a′ reacts with AgOTf (OTf = O3SCF3) and XyNC or CO to give complexes [Rh(η5-Cp*){CH2CH 2CF(CF3)2}(CNXy)(PPh3)]OTf (6) or [Rh(η5-Cp*){C(O)CH2CH2CF(CF 3)2}(CO)(PPh3)]OTf (7), respectively. Complex [Rh(η5-Cp*)I(py)(PMe3)]BF4 (8) was obtained either by reaction of (1) [Rh(η5-Cp*) (η2-C2H4)(PMe3)] with [I(py)2]BF4 or (2) [Rh(η5-Cp*)I 2(PMe3)] with AgBF4 and py. The crystal structures of 1a, 1b, 3c, 4g, 7, and 8 have been determined.
- Gil-Rubio, Juan,Guerrero-Leal, Juan,Blaya, Maria,Vicente, Jose,Bautista, Delia,Jones, Peter G.
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p. 1287 - 1299
(2012/04/10)
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- Environmentally Benign Processes for Making Useful Fluorocarbons: Nickel- or Copper(I) Iodide-Catalyzed Reaction of Highly Fluorinated Epoxides with Halogens in the Absence of Solvent and Thermal Addition of CF2I 2 to Olefins
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Highly fluorinated epoxides react with halogens in the presence of nickel powder or CuI at elevated temperatures to provide a useful and general synthesis of dihalodifluoromethanes (CF2X2) and fluoroacyl fluorides (RFCOF) in the absence of solvent. At 185 °C, hexafluoropropylene oxide and halogens produce CF2X 2 (X = I, Br) in 68-90% isolated yields, along with small amounts of X(CF2)nX, (n = 2, 3). With interhalogens I-X (X = Cl, Br), a mixture of CF2I2, CF2XI, and CF 2X2 was obtained. The fluorinated epoxides substituted with perfluorophenyl, fluorosulfonyl, and chlorofluoroalkyl groups also react cleanly with iodine to give CF2I2 and the corresponding fluorinated acyl fluorides in good yields. The reaction probably involves an oxidative addition of fluorinated epoxides into metal surfaces to form an oxametallacycle, followed by rapid decomposition to difluorocarbene-metal surfaces, which alters the reactivity of the difluorocarbene carbon from electrophilic to nucleophilic. The increase of nucleophilicity of difluorocarbene facilitates the reaction with electrophilic halogens. CF 2I2 reacted with olefins thermally to give 1,3-diiodofluoropropane derivatives. Both fluorinated and nonfluorinated alkenes gave good yields of the adducts. Reaction with ethylene, propylene, perfluoroalkylethylene, vinylidene fluoride, and trifluoroethylene provided the corresponding adducts in 58-86% yields. With tetrafluoroethylene, a 1:1 adduct was predominantly formed along with small amounts of higher homologues. In contrast to perfluoroalkyl iodides, CF2I2 also readily adds to perfluorovinyl ethers to give 1,3-diiodoperfluoro ethers.
- Yang, Zhen-Yu
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p. 2394 - 2403
(2007/10/03)
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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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- Oxidative coupling of radicals in reactions of compounds of tervalent iodine with trimethylsilyl(phenyl)acetylene
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Reactions of trimethylsilyl(phenyl)acetylene with aryl and alkyl difluoroiodides give coupling products of substituents in high yields.
- Lermontov,Velikohat'ko,Zefirov
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p. 977 - 978
(2007/10/03)
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- MEASUREMENT OF RATE CONSTANTS AND EQUILIBRIUM CONSTANTS OF RI R + I AND I + RI I2 + R FOR R = C3F7, iso-C3F7, C6F13, CF3OCF2CF2, OR C3F7OCF2CF2
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The method of isothermal pyrolysis of an iodide RI can produce highly accurate data about the equilibrium constants and rate constants of the reactions RI R + I and I + RI R + I2, if the rate constant for recombination R + R -> R2 is known.Data on the absolute rate constants of the thermal dissociation of the iodides C3F7I, iso-C3F7I, C6F13I, CF3O(CF2)2I and C3F7O(CF2)2I, and also for their reaction with atomic iodine were obtained for the first time using this technique.The dissociation energies ED (R-I) are 212+/-2, 201+/-2, 202+/-2, 213+/-2, and 213+/-2 kJ/mole, respectively.
- Skorobogatov, G. A.,Dymov, B. P.,Tedeev, R. Sh.
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p. 158 - 165
(2007/10/02)
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- REACTIONS OF TeF5OCl WITH FLUOROCARBON IODIDES AND SYNTHESIS OF CF3OTeF5
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The low temperature reaction of TeF5OCl with the fluorocarbon iodides, CF3I, C2F5I, n-C3F7I, and i-C3F7I results in the formation of RfI(OTeF5)2 adducts.Except for the trifluoromethyl derivative these are stable, colorless compounds.The trifluoromethyl adduct decomposes above -78 deg C to give the previously unknown CF3OTeF5.The perfluoroethyl and n-propyl adducts decompose at 120 deg C or under UV radiation giving C2F5OTeF5 and n-C3F7OTeF5, respectively.These reactions constitute a new synthesis of primary RfOTeF5 compounds.Attempts to extend this synthesis to secondary fluorocarbon iodides were unsuccessful.
- Schack, Carl J.,Christe, Karl O.
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- CO2 Laser Induced Chain Reaction of C2F4 + CF3I
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A pulsed CO2 laser was used to induce the telomerization of CF3I with C2F4 in gas phase.This is an exothermic radical chain reaction, producing CF3(CF2)nI with low n.A problem, previously considered unresolvable, exists at low pressure: Good primary quantum yield is in conflict with long chain length; for kinetic reasons the chain length is short, if initially a high yield of radicals is generated by IR multiphoton dissociation.Radical dimers dominate in this case.To avoid this undesired direction of the reaction, we applied a novel method: At high pressure theradicals are generated with delay only, so that their instantaneous concentration is always small.At 3 bar we attained quantum yields of 0.2 for the desired iodides, with selectivity of 80percent.This good selectivity is a consequence of the second-order termination, according to our analysis.The quantum yield is 100 times larger than previously reported for a CO2 laser induced reaction.It can be raised even more, if the exothermicity is used for further propagation.We only came close to this ignition threshold.With more laser energy in longer pulses, it could be reached.
- Mengxiong, Gong,Fuss, W.,Kompa, K. L.
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p. 6332 - 6337
(2007/10/02)
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- THERMOLYSIS AND UV-PHOTOLYSIS OF PERFLUORINATED IODO-ALKANES AND IODO-OXAALKANES: THERE IS A PREFERRED REACTION CHANNEL
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The thermal stability of perfluorinated iodides depends on their structure and decreases in the order of RFCF2CF2I>RFCF2CF(CF3)I>RFOCF(CF3)I=RFCF2C(CF3)2I.The major decomposition path consists of the elimination of an unsaturated compound (CF2=CF2, CF2=CF-CF3, O=CF-CF3, CF2=C(CF3)2, respectively) with concomitant formation of RFI.The highest selectivities were found for tertiary iodides and 2-iodo-3-oxaalkanes, whose decomposition is virtually irreversible.UV-photolysis of the iodo-compounds gave the same products as the thermolysis reactions.
- Probst, Anton,Werner, Konrad von
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p. 163 - 173
(2007/10/02)
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- Perfluoroalkyl compounds and process for preparing the same
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Perfluoroalkyl compounds represented by the formula (I): STR1 wherein Rf represents a perfluoroalkyl group having 1 to 20 carbon atoms, Ar represents a substituted or unsubstituted phenyl group wherein the substituent is an alkyl group having 1 to 4 carbon atoms or a halogen atom, I represents an iodine atom, and A represents a perfluoroalkyl group having 1 to 20 carbon atoms which can be the same or different from Rf, a hydroxy group an alkyl group having 1 to 4 carbon atoms, an aryl group or a halogen atom, and processes for preparing the perfluoroalkyl compounds represented by the formula (I).
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- REACTIONS OF PERFLUOROALKYL IODIDES WITH PHOSPHORUS(III) ESTERS. KINETICS AND MECHANISM OF THE REACTIONS OF HEPTAFLUOROPROPYL IODIDE WITH ETHYLPHOPHONOUS ESTERS
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1.The kinetics of the fluoroalkylation of ethylphosphonous esters were studied, and it was shown that for the reaction low values of effective activation energy are characteristic. 2.In the first stage of the reactions of phosphonous esters with heptafluoropropyl iodide the formation of donor-acceptor complexes ocurs. 3.The rate-determining stage of the complex process is the stage of the formation of the intermediate compound.
- Garabadzhiu, A. V.,Ivanov, S. A.,Lavrent'ev, A. N.,Shibaev, V. I.
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p. 1905 - 1910
(2007/10/02)
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