- Kinetic and mechanistic study of OH- and Cl-initiated oxidation of two unsaturated HFCs: C4F9CH=CH2 and C6F13CH=CH2
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The kinetics and mechanisms of the OH- and Cl-initiated oxidation of two unsaturated HFCs, C4F9CH=CH2 and C6F13CH=CH2, were investigated. The kinetic study was performed as a function of pressure and temperature for the OH reactions and as a function of pressure at 298 K for Cl atom reactions. The rate constants obtained are (in units of cm3 molecule-1 s-1): κ(OH + C4F9CH=CH2) = (8.5 ±1.4) x 10-13 exp[(139 ±48)/T] and κ(OH + C6F13CH=CH2) = (1.3 ±0.5) x 10-12 exp[(31 ±124)/T] in the temperature range 233-372 K; and κ(Cl + C4F9CH=CH2) = (8.9 ±1.0) x 10-11 and κ(C1 + C6F13CH=CH2) = (9.1 ± 1.0) x 10-11 at 298 K. The OH and Cl reactions rate constants were found to be independent of pressure in the range 10-760 and 15-60 Torr, respectively. The mechanistic study was performed in air at atmospheric pressure, in the presence or absence of NOx. CO and COF2 have been identified as the major secondary products of both OH- and Cl-initiated oxidation of the HFCs. However, there is evidence for the formation of different primary products: aldehydes (C4F9CHO and C6F13CHO) in the OH oxidation of the HFCs and ketones (C4F9C(O)CH2C1 and C6F13C(O)CH2Cl) in the Cl oxidation. This suggests that the oxy radicals, precursors of these carbonyl compounds, behave differently. The β-hydroxyoxy radicals C4F9CH(O)CH2OH and C6F13CH(O)CH2OH decompose, whereas the β-chlorooxy radicals C4F9CH(O)CH2C1 and C6F13CH(O)CH2C1 react with O2. These results are consistent with the significantly higher activation barrier for the decomposition of the β-chlorooxy, compared to that of the β-hydroxyoxy radicals.
- Vésine,Bossoutrot,Mellouki,Le Bras,Wenger,Sidebottom
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- An improved synthesis of perfluoroalkyl aldehydes from the reaction of perfluoroalkyl iodides with dimethylformamide
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The reactivity of perfluoroalkyl iodide in the presence of a zinc-copper metal couple and a radical initiator in DMF, has been investigated.This led to the formation of a mixture of N,N-dimethyl perfluoroalkylamide and perfluoroalkyl aldehyde.After studying the influence of different reaction parameters, the perfluoroalkyl aldehyde formation has been optimized to high yield (over 90percent).
- Benefice-Malouet, S.,Blancou, H.,Commeyras, A.
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- Incorporation of a 3-(2,2,2-Trifluoroethyl)-γ-hydroxy-γ-lactam motif in the side chain of 4-aminoquinolines. Syntheses and antimalarial activities
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In this paper we report the synthesis and antimalarial properties of two series of fluoroalkylated γ-lactams derived from 4-aminoquinoline as potent chemotherapeutic agents for malaria treatment. These molecules obtained in several steps resulted in the identification of very potent structures with in vitro activity against Plasmodium falciparum clones of variable sensitivity (3D7 and W2) in the range of 19-50 nM with resistance indices in the range of 1.0-2.5. In addition, selected molecules (50, 51, 58, 60, 63, 70, 72, 74, 78, 81, 84, and 87) that are representative of the two series of compounds did not show cytotoxicity in vitro when tested against human umbilical vein endothelial cells up to a concentration of 100 μM. The most promising compounds (82 and 84) showed significant IC50 values close to 26 and 19 nM against the chloroquino-sensitive strain 3D7 and 49 and 42 nM against the multi-drug-resistant strain W2. Furthermore, two model compounds (50 and 70) were found to be quite stable over 48 h at pH 7.4 and 5.2. Overall, our preliminary data indicate that this class of structures contains promising candidates for further study.
- Cornut, Damien,Lemoine, Hugues,Kanishchev, Oleksandr,Okada, Etsuji,Albrieux, Florian,Beavogui, Abdoul Habib,Bienvenu, Anne-Lise,Picot, Stéphane,Bouillon, Jean-Philippe,Médebielle, Maurice
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- The gas phase tropospheric removal of fluoroaldehydes (CxF 2x+1CHO, x = 3, 4, 6)
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The rate coefficient of the OH reaction with the perfluoroaldehydes C 3F7CHO and C4F9CHO have been determined in the temperature range 252-373 K using the pulsed laser photolysis-laser induced fluorescence (PLP-LIF) method: kC3F7CHO+OH = (2.0 ± 0.6) × 10-12 exp[-(369 ± 90)/T] and kC4F9CHO+OH = (2.0 ± 0.5) × 10-12 exp[-(356 ± 70)/T] cm3 molecule-1 s-1, corresponding to (5.8 ± 0.6) × 10-13 and (6.1 ± 0.5) × 10-13 cm3 molecule-1 s -1, respectively, at 298 K. The UV absorption cross sections of these two aldehydes and CF3(CF2)5CH2CHO have been measured over the range 230-390 nm at 298 K and also at 328 K for CF3(CF2)5CH2CHO. The obtained results for C3F7CHO and C4F9CHO are in good agreement with two recent determinations but the maximum value of the absorption cross section for CF3(CF2)5CH 2CHO is over a factor of two lower than the single one recently published. The photolysis rates of C3F7CHO, C 4F9CHO and CF3(CF2)5CHO have been measured under sunlight conditions in the EUPHORE simulation chamber in Valencia (Spain) at the beginning of June. The photolysis rates were, respectively, Jobs = (1.3 ± 0.6) × 10-5, (1.9 ± 0.8) × 10-5 and (0.6 ± 0.3) × 10 -5 s-1. From the Jobs measurements and calculated photolysis rate Jcalc, assuming a quantum yield of unity across the atmospheric range of absorption of the aldehydes, quantum yields Jobs/Jcalc = (0.023 ± 0.012), (0.029 ± 0.015) and (0.046 ± 0.028) were derived for the photodissociation of C3F7CHO, C4F9CHO and CF 3(CF2)5CHO, respectively. The atmospheric implication of the data obtained in this work is discussed. The main conclusion is that the major atmospheric removal pathway for fluoroaldehydes will be photolysis, which under low NOx conditions, may be a source of fluorinated carboxylic acids in the troposphere. the Owner Societies.
- Solignac,Mellouki,Le Bras,Yujing, Mu,Sidebottom
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p. 4200 - 4210
(2008/09/19)
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- Atmospheric chemistry of fluorinated alcohols: Reaction with Cl atoms and OH radicals and atmospheric lifetimes
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Relative rate techniques were used to study the kinetics of the reactions of Cl atoms and OH radicals with a series of fluorinated alcohols, F(CF2)nCH2OH (n = 1-4), in 700 Torr of N2 or air diluent at 296 ± 2 K. The length of the F(CF2)n group had no discernible impact on the reactivity of the molecule. For n = 1-4, k(Cl + F(CF2)nCH2OH) = (6.48 ± 0.53) × 10-13 and k(OH + F(CF2)nCH2OH) = (1.02 ± 0.10) × 10-13 cm3 molecule-1 s-1. Product studies of the chlorine initiated oxidation of F(CF2)nCH2OH (n = 1-4) in the absence of NO show the sole primary product to be the corresponding aldehyde, F(CF2)nC(O)H. Consideration of the likely rates of other possible atmospheric loss mechanisms leads to the conclusion that the atmospheric lifetime of F(CF2)nCH2OH (n ≥ 1) is determined by reaction with OH radicals and is approximately 164 days.
- Hurley,Wallington,Sulbaek Andersen,Ellis,Martin,Mabury
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p. 1973 - 1979
(2007/10/03)
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- Gas phase UV and IR absorption spectra of CxF2x+1CHO (x = 1-4)
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The UV and IR spectra of CxF2x +1CHO (x = 1-4) were investigated using computational and experimental techniques. CxF2x+1CHO (x = 1-4) have broad UV absorption features centered at 300-310 nm. The maximum absorption cross-section increases significantly and shifts slightly to the red with increased length of the CxF2x+1 group: CF3CHO, 3.10 × 10-20 (300 nm); C 2F5CHO, 6.25 × 10-20 (308 nm); C 3F7CHO, 8.96 × 10-20 (309 nm); and C 4F9CHO, 10.9 × 10-20 (309 nm). IR spectra for CxF2x+1CHO were recorded, calculated, and assigned. Results are discussed with respect to the literature data and to the atmospheric fate of CxF2x+1CHO.
- Hashikawa,Kawasaki,Waterland,Hurley,Ball,Wallington,Andersen, M.P. Sulbaek,Nielsen
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p. 1925 - 1932
(2007/10/03)
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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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- Functionally Substituted Organic Peroxides. XIX. Kinetics of the Reaction of Poly- and Perfluorinated Carbonyl Compounds with tert-Butyl Hydroperoxide
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The kinetics of noncatalytic reaction of fluorinated aliphatic and aromatic aldehydes, alkyl, cycloalkyl, and aryl ketones, and β-ketoesters with tert-butyl hydroperoxide were studied by IR spectroscopy.
- Chapurkin
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- SnX2/Al-promoted formylation of per(poly)fluoroalkyl halides with N,N-dimethylformamide
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In the presence of catalytic amounts of stannous salts (20 molpercent) and aluminium powder, per(poly)fluoroalkyl iodides or bromides react smoothly with DMF under mild conditions to give the corresponding per(poly)fluoroalkyl aldehydes in good to excellent yield.A tin-containing intermediate was obtained.A possible mechanism is proposed.
- Hu, Chang-Ming,Chen, Jian
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p. 189 - 192
(2007/10/03)
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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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