- Study on the pyrolysis characteristics of a series of fluorinated cyclopentenes and implication of their environmental influence
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3,3,4,4,5,5-hexafluorocyclopentene (6FE), 1,3,3,4,4,5,5-heptafluorocyclopentene (7FE) and octafluorocyclopentene (8FE) are considered as new generation of potential chlorofluorocarbons substitutes. To investigate the thermostabilities, tubular furnace experiments were designed over temperature range of 500-850℃. The results show that 6FE, 7FE and 8FE are all stable below 650 ℃, thus have good stabilities in common storage and practical use condition. Furthermore, considering the short atmospheric lifetimes (several months), low global warming potentials (GWPs, less than 119) and zero ozone depletion potentials (ODPs), the compounds seem no big influences on the climate change.
- Bi, Fang,Gao, Rui,Ji, Yuanyuan,Li, Hong,Li, Ling,Liu, Chenfei,Wang, Xuezhong,Wu, Zhenhai,Yanqin, Ren,Zhang, Hao,Zhang, Xin
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- Explored routes to unknown polyfluoroorganyliodine hexafluorides, R FIF6
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Two routes to RFIF6 compounds were investigated: (a) the substitution of F by RF in IF7 and (b) the fluorine addition to iodine in RFIF4 precursors. For route (a) the reagents C6F5SiMe3, C6F 5SiF3, [NMe4][C6F 5SiF4], C6F5BF2, and 1,4-C6F4(BF2)2 were tested. C 6F5IF4 and CF3CH2IF 4 were used in route (b) and treated with the fluoro-oxidizers IF7, [O2][SbF6]/KF, and K2[NiF 6]/KF. The observed sidestep reactions in case of routes (a) and (b) are discussed. Interaction of C6F5SiX3 (X = Me, F), C6F5BF2, 1,4-C6F 4(BF2)2 with IF7 gave exclusively the corresponding ring fluorination products, perfluorinated cyclohexadiene and cyclohexene derivatives, whereas [NMe4][C6F 5SiF4] and IF7 formed mixtures of C 6FnIF4 and C6FnH compounds (n = 7 and 9). CF3CH2IF4 was not reactive towards the fluoro-oxidizer IF7, whereas C6F 5IF4 formed C6FnIF4 compounds (n = 7 and 9). C6F5IF4 and CF 3CH2IF4 were inert towards [O 2][SbF6] in anhydrous HF. CF3CH 2IF4 underwent C-H fluorination and C-I bond cleavage when treated with K2[NiF6]/KF in HF. The fluorine addition property of IF7 was independently demonstrated in case of perfluorohexenes. C4F9CFCF2 and IF7 underwent oxidative fluorine addition at -30 °C, and the isomers (CF 3)2CFCFCFCF3 (cis and trans) formed very slowly perfluoroisohexanes even at 25 °C. The compatibility of IF7 and selected organic solvents was investigated. The polyfluoroalkanes CF 3CH2CHF2 (PFP), CF3CH 2CF2CH3 (PFB), and C4F9Br are inert towards iodine heptafluoride at 25 °C while CF3CH 2Br was slowly converted to CF3CH2F. Especially PFP and PFB are new suitable organic solvents for IF7.
- Frohn, Hermann-Josef,Bardin, Vadim V.
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experimental part
p. 1000 - 1006
(2010/11/16)
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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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- 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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- ACTION OF VANADIUM AND ANTIMONY PENTAFLUORIDES ON POLYFLUORINATED DERIVATIVES OF CYCLOHEXADIENE
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Polyfluorinated 1,3- and 1,4-cyclohexadienes are fluorinated by vanadium fluoride at -25 to 25 deg C.The olefinic fragments of perfluoro-1,3- and perfluoro-1,4-cyclohexadienes are close to each other in reactivity.Under the influence of vanadium pentafluoride the fluorine atoms add to 1-R-heptafluoro-1,4-cyclohexadienes preferentially at the multiple bond containing the less electron-withdrawing substituent.At -80 to 20 deg C antimony pentafluoride leads to isomerization of the polyfluorinated derivatives of cyclohexadiene.
- Avramenko, A. A.,Bardin, V. V.,Furin, G. G.,Karelin, A. I.,Krasil'nikov, V. A.,Tushin, P. P.
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p. 1298 - 1303
(2007/10/02)
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- SUBSTITUTION AND ADDITION REACTIONS OF NF4BF4 WITH AROMATIC COMPOUNDS
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Benzene, toluene, and nitrobenzene interact rapidly with NF4BF4 in anhydrous HF to give, almost exclusively, fluorine substituted aromatic derivatives.Up to four hydrogens can be replaced in a rapid reaction, before a much slower addition reaction takes over.The direction of the substitution in C6H6, C6H5CH3 and C6H5NO2 and the lack of side chain fluorination in C6H5CH3 support an electrophilic substitution mechanism.These rapid substitution reactions are followed by much slower fluorine addition reactions to give the corresponding cyclo-hexadienes and -hexenes.These addition reactions were also studied separately using tetra-, penta-, and hexa- fluorobenzene as the starting materials.In these addition reactions, almost no hydrogen substitution occurred.The addition of the first pair of fluorines always gave 1,4-cyclohexadienes in which the CF2 group was adjacent to hydrogen on the ring.The addition of the second pair of fluorines resulted in the formation of cyclohexenes.These reactions occured in high yield and offer a controlled, high yield path to dienes.All products were characterized spectroscopically and by comparison to literature data.
- Schack, Carl J.,Christe, Karl O.
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p. 363 - 374
(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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- THE THERMAL ISOMERIZATION OF HEPTAFLUOROCYCLOHEXADIENES
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The evidence for the involvement of sigmatropic fluorine migrations in the isomerizations of fluorinated polyenes is reviewed and the difficulties inherent in providing satisfactory rationalizations are discussed.The thermal isomerizations of heptafluorocyclohexadienes under various reaction conditions are described.It is established that such isomerizations occur by a mechanism which does not involve catalysis by fluoride ion, however the exact mechanistic pathway remains uncertain.
- Feast, W. J.,Morland, J. B.
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- THE SIGMATROPIC MIGRATION OF FLUORINE
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Pyrolysis of polyfluorocyclohexadienes at 475-480 deg C over new quartz or Pyrex glass gave products derived from 1,5-sigmatropic migrations of fluorine; 1,3-migrations occurred to only a small degree.As the quartz or glass aged, other processes - 1,3-migrations and defluorinations to aromatics - began to occur; these appear to be due in some way to fluoride ion, since pyrolysis over sodium fluoride gave similar products.
- Burdon, J.,Childs, A.,Parsons, I. W.,Rimmington, T. W.
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