- Studies on polyhaloalkanes. V. A new reduction system: zinc/hydrazine hydrate
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Using zinc/hydrazine hydrate as a new reduction system, polyfluoroalkyl halides such as Cl(CF2)nH (1a-c, n = 4, 6, 8), Cl(CF2)nI (1e-g, n = 4, 6, 8) and R(CF2)nCl (n = 4, 6, 1h,i) have been converted to the corresponding reduction products H(CF2)nH (2a-g, n = 4, 6, 8) and R(CF2)nH (n = 4, 6, 2h,i) in high yield.Reduction of the CF2Cl group was faster than that of the CHI in the reaction of 1m. - Keywords: Polyhaloalkanes; Reduction; Zinc/hydrazine hydrate system; NMR spectroscopy; Mass spectrometry
- Wu, Fang-Hong,Huang, Bing-Nan,Huang, Wei-Yuan
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- Organofluorine compounds and fluorinating agents part 17: Sonochemical-forced preparation of perfluoroalkanals and their use for non-conventional acetalations of carbohydrates 1, 2
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The homologous 1-iodo-perfluoroalkanes 1a-1c and α,ω-dibromo-perfluoroalkanes 4a, 4b were carbonylated with DMF in the presence of Al/SnCl2 or Al/PbBr2 under sonication in a short reaction time. The hydrated aldehydes 2a-2c and 5a, 5b respectively were obtained in good yields allowing dehydration to 3a-3c and 6a, 6b. Some of the fluorinated aldehydes were selected as substrates in a Wittig-Horner olefination assisted by ultrasound and in non-conventional acetalations of methyl α-L-rhamnopyranoside (9). Thus, (E)-1-perfluorooctyl-2-phenylsulphonyl-ethene (8) was prepared from 3c and the phosphonate 7 by Wittig-Horner synthesis. Acetalations of 9 were carried out with the aldehydes (3a, 3b, 6a), hydrated aldehydes (2a, 2b), and the aldehyde hemiacetal 12 respectively, in the presence of dicyclohexylcarbodiimide (DCC). In all cases, a selective epimerization was observed at the C-atom 3 of the monosaccharide, i.e. polyfluoroalkylidenated 6-deoxy-α-L-altropyranosides 10, 11, 13, and 14 were obtained.
- Miller, Alexey O.,Peters, Dietmar,Zur, Cornelia,Frank, Michael,Miethchen, Ralf
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- Method for preparing α-substituted ω-hydroperfluoroalkanes
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A method for the preparation of α-substituted ω-dihydroperluoroalkane derivatives of the general formula H(CF2 CF2)n R wherein R=H or COOH, and n=1-10 is characterized by oxidizing α, α, ω-trihydroperfluoroalcohols with an oxygen gas or an oxygen-containing gas in the presence of a homogeneous copper catalyst and an alkaline agent in an organic solvent with subsequent isolation of the desired product.
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- A novel synthesis of per(poly)fluoroalkyl aldehydes
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A novel synthesis of per(poly)fluoroalkyl aldehydes in high yield by the reaction of per(poly)fluoroalkyl iodides or bromides with dimethylformamide initiated by a PbBr2(catalyst)/Al bimetal redox system is described.
- Hu, Chang-Ming,Tang, Xiao-Qing
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p. 217 - 222
(2007/10/02)
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- SOLVENT EFFECTS IN BETWEEN PERFLUOROALKYLIODIDES AND CADMIUM
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The interaction between perfluoroorgano iodides (RfI where Rf = F(CF3)2C(CF2CF2)3, n-C6F13, n-C8F17, F(CF3)2COCF2CF2, F(CF3)2CO(CF2CF2)4 and C2H5OC(O)(CF2CF2)2OCF2CF2) with cadmium in an acetonitrile solvent media produces primarily the coupled products (RfRf, 72-90percent yield) in addition to minor quantities of the reduction products (RfH).On the other hand ICF2CF2I and ClCF2CFClI, by a 1,2-dehalogenation reaction, from the olefins CF2=CF2 and CF2=CFCl, respectively, as the principal products.The interaction of RfI compounds with cadmium in other solvent media, e.g. diethyl ether, tetrahydrofuran (YHF)), N,N-dimethylformamide (DMF), and bis(2-methoxyethyl)ether(diglyme) were examined and found to produce a different ratio of RfRf and RfH products.
- Chen, Grace J.,Tamborski, Christ
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p. 123 - 140
(2007/10/02)
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- Thermal Decomposition of Some Perfluoro- and Polyfluorodiacyl Peroxides
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Seven polyfluoroacyl peroxides were synthesized, some of them by a new procedure involving the direct interaction of an acyl fluoride with hydrogen peroxide.In the temperature range of 20-40 deg C, all these peroxides undergo first-order decomposition in dilute 1,1,2-trichloro-1,2,2-trifluoroethane (Freon-113) solutions (F-RF.Differing from other perfluoro or polyfluoro radicals, the perfluoro-α-isopropoxyethyl radicals (10) undergo substantial β scission to form perfluoroisopropyl radicals (11) during their lifetime.The ΔHexc. values for the perfluoroacyl peroxides are about 24 kcal mol-1, or about 5 kcal lower than that of the nonfluorinated diacyl peroxides (ca. 29 kcal mol-1).Apparently, the higher relative rates for 3 and 7 are caused by different factors.The latter peroxide (7) decomposes with a more favorable ΔSexc. term, whereas the former (3) decomposes with lower values of both ΔHexc. and ΔSexc..Thus, weakening of the peroxide bond by H bonding of the peroxide oxygen atom with the acidic ω-hydrogen atom seems to be implicated in the decomposition of 3.With a half-life of 81 min at 20 deg C, 3 may become a useful low-temperature initiator for free-radical reactions and polymerization.
- Chengxue, Zhao,Renmo, Zhou,Heqi, Pan,Xiangshan, Jin,Yangling, Qu,et al.
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p. 2009 - 2013
(2007/10/02)
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- Conformational energies of perfluoroalkanes. 5. Dipole moments of H(CF2)nH and H(CF2)nI
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Dielectric and refractive index increments at 25°C are reported for some α,ω-dihydroperfluoroalkanes and α-hydro-ω-iodoperfluoroalkanes in benzene and CCl4. Similar measurements on perfluorocyclohexane and perfluoro-n-hexane are used to deduce effective atomic polarizations for fluorocarbons in solution. The dipole moments obtained lead to a somewhat smaller characteristic ratio for the perfluoroalkane chain than had earlier been estimated by Bates and Stockmayer.
- Matsuo, Keizo,Stockmayer, Walter H.
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p. 3307 - 3311
(2007/10/02)
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