76-04-0Relevant articles and documents
Atmospheric sink of methyl chlorodifluoroacetate and ethyl chlorodifluoroacetate: Temperature dependent rate coefficients, product distribution of their reactions with Cl atoms and CF2ClC(O)OH formation
Blanco, María B.,Barnes, Ian,Wiesen, Peter,Teruel, Mariano A.
, p. 51834 - 51844 (2016/06/14)
Rate coefficients as a function of temperature have been measured for the first time for the gas-phase reactions of chlorine atoms with methyl chlorodifluoracetate (k1) and ethyl chlorodifluoroacetate (k2) using the relative rate technique. The experiments were carried out in a 1080 L photoreactor over the temperature range 287-313 K at a total pressure of 1000 ± 10 mbar of synthetic air using in situ FTIR spectroscopy to monitor reactants and products. The following Arrhenius expressions were obtained: k(MCDFA+Cl) = (9.6 ± 5.1) × 10-12exp[-(1363 ± 79)/T] and k(ECDFA+Cl) = (64.4 ± 29.7) × 10-12exp[-(1110 ± 68)/T]. The kinetic results are compared with previous experimental and theoretical studies. In addition, a product study of the reactions of Cl with methyl chlorodifluoracetate and ethyl chlorodifluoroacetate is reported. The results indicate that in the absence of NOx the main fate of the alkoxy radicals formed after H-atom abstraction by Cl from the -CH3 group in methyl chlorodifluoroacetate is reaction of the radical with O2 to form the mixed anhydride CF2ClC(O)OC(O)H. In the case of ethyl chlorodifluoroacetate the main fate of the alkoxy formed via H-atom abstraction by Cl from the -CH2- entity in the ethyl group is α-ester rearrangement to produce chlorodifluoroacetic acid and the corresponding radical. The yields of chlorofluoracetic acid (CF2ClC(O)OH) obtained were as follows: (34 ± 5)% and (86 ± 8)% for the reactions of Cl with CF2ClC(O)OCH3 and CF2ClC(O)OCH2CH3, respectively. The measured yields are rationalized in terms of mechanisms consisting of competitive reaction channels for the formed products in the oxidation, i.e. reaction with O2, α-ester rearrangement and a decomposition pathway. Atmospheric implications are discussed according to the rate coefficients obtained as a function of temperature and altitude, and regarding the formation of chlorofluorocarboxylic acid.
Preparation and properties of two novel selenoacetic acids: HCF 2C(O)SeH and ClCF2C(O)SeH
Gomez Castano, Jovanny A.,Romano, Rosana M.,Beckers, Helmut,Willner, Helge,Della Vedova, Carlos O.
body text, p. 2608 - 2615 (2012/05/04)
The novel selenocarboxylic Se-acids, HCF2C(O)SeH and ClCF 2C(O)SeH, were prepared by treating the corresponding carboxylic acids with Woollins' reagent. The boiling points were extrapolated from the vapor pressure curves to be 364 and 359 K for HCF2C(O)SeH and ClCF2C(O)SeH, respectively. Both compounds are unstable at ambient temperatures and decompose to the corresponding seleno anhydrides and release of H2Se. Hydrolysis results in formation of the carboxylic acids and hydrogen selenide, while diselenides presumably are obtained by oxidation. The conformational properties of these acids were studied by vibrational spectroscopy in combination with ab initio and DFT methods. IR vapor-phase spectra, Raman spectra of the neat liquids, and IR spectra of the Ar-matrix-isolated compounds deposited at two different nozzle temperatures were interpreted in terms of quenching conformational equilibria. The most stable structure of both acids was found to be syn-gauche in equilibrium with a second anti-syn form in HCF2C(O)SeH and with another two conformers, anti-gauche and anti-syn, in ClCF2C(O)SeH.
Preparation of compounds comprising a CHF2 or CHF group
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Page/Page column 2; 3, (2008/06/13)
Producing compounds (I) with a mono- or difluoromethyl group from compounds (II) with a mono- or difluorohalomethyl group, where halo is bromo, iodo or preferably chloro, comprises reacting (II) with zinc in the presence of an alcohol. An independent claim is also included for an azeotropic mixture of methyl difluoroacetate and methanol.