- High surface area chromium(III)fluoride – Preparation and some properties
-
Reaction of hydrated hydrazinium fluorochromate(III), [N2H6][CrF5]·H2O, with fluorine (F2)in anhydrous hydrogen fluoride (aHF)medium at room temperature yields completely amorphous CrF3-based materials with exceptionally high specific surface areas of 180–420 m2 g?1 (HS-CrF3). The stepwise reaction starts with the oxidative decomposition of the cationic part of the precursor with F2 that gives a CrF3 intermediate with low surface area. In the following step, part of Cr3+ is oxidized to Cr>3+, and in the presence of residual H2O/[H3O]+ species Cr>3+ fluoride oxides are formed. Formation of volatile chromium compounds, mainly CrO2F2, is apparently the key step in HS-CrF3 formation. Removal of these components from the final product reduces the oxygen content, and generates microporosity. The HS-CrF3 materials are completely amorphous with a bulk composition that is close to stoichiometric CrF3. Small amounts of Cr>3+ and oxygen in the final product very likely originate from the retained non-volatile CrOF3. The HS-CrF3 materials are Lewis acids and exhibit a high reactivity towards chlorofluorocarbons (CFCs)evidenced by substantial F/Cl exchange between CFCs and the solid fluoride. High reactivity of these new materials can be ascribed to their nanoscopic nature, exceptionally high surface area, and low levels of impurities. As such, they represent an interesting new class of benchmark fluoride materials applicable in fluorocarbon chemistry.
- Tav?ar, Ga?per,Skapin, Toma?
-
-
- PROCESSES FOR PRODUCING CHLOROFLUOROCARBON COMPOUNDS USING INORGANIC FLUORIDE
-
Methods and systems for producing chlorofluorocarbon with an inorganic fluoride (e.g., germanium tetrafluoride (GeF4)) are disclosed herein.
- -
-
Page/Page column 4
(2008/12/04)
-
- Functionalized Copolymers of Terminally Functionalized Perfluoro (Alkyl Vinyl Ether) Reactor Wall for Photochemical Reactions, Process for Increasing Fluorine Content in Hydrocaebons and Halohydrocarbons and Olefin Production
-
A photochemical reaction apparatus including a reactor and a light source situated so that light from the light source is directed through a portion of the reactor wall is disclosed. The apparatus is characterized by the portion of the reaction wall comprising a functionalized copolymer of a terminally functionalized perfluoro(alkyl vinyl ether). Also described is a photochemical reaction process using said reactor. The functional group of the copolymer of the apparatus and the process is selected from —SO2F, —SO2CI, —SO3H, —CO2R (where R is H or C1-C3 alkyl), —PO3H2, and salts thereof. A process for increasing the flourine content of at least one compound selected from hydrocarbons and halohydrocarbons, comprising: (a) photochlorinating said at least one compound, and (b) reacting the halogenated hydrocarbon in (a) with HF. A process for producing an olefinic compound, comprising: (a) photochlorinating at least one compound selected from hydrocarbons and halohydrocarbons containing at least two carbon atoms and at least two hydrogen atoms to produce a halogenated hydrocarbon containing a hydrogen substituent and a chlorine substituent on adjacent carbon atoms; and (b) subjecting the halogenated hydrocarbon produced in (a) to dehydrohalogenation.
- -
-
Page/Page column 5
(2008/06/13)
-
- PHOTOCHLORINATION AND FLUORINATION PROCESS FOR PREPARATION OF FLUORINE-CONTAINING HYDROCARBONS
-
A process is disclosed for increasing the fluorine content of at least one compound selected from halohydrocarbons and hydrocarbons. The process involves (a) directing light from a light source through the wall of a reactor to interact with reactants comprising chlorine and said at least one compound in said reactor, thereby producing a halogenated hydrocarbon having increased chlorine content by photochlorination, and (b) reacting said halogenated hydrocarbon produced by the photochlorination in (a) with HF; and is characterized by the light directed through the reactor wall being directed through a poly(perhaloolefin) polymer.
- -
-
Page/Page column 10; 11
(2008/06/13)
-
- Nitrogen trifluoride as an oxidative co-reagent in high temperature vapor phase hydrofluorinations
-
Nitrogen trifluoride (NF3) has proven to be a useful additive in high temperature vapor phase hydrofluorination reactions of chlorocarbons. The activity of chromium-based catalysts is maintained by introducing a co-stream of NF3 into the reagent chlorocarbon and HF stream. NF3 is a desirable additive instead of O2 as there is no water generation due to its use.
- Belter, Randolph K.,Sweval, Mark S.,Iikubo, Yuichi
-
p. 816 - 820
(2008/03/27)
-
- PROCESS FOR THE PREPARATION OF 1,1,1,2,2-PENTAFLUOROETHANE
-
A process for the preparation of pentafluoroethane is disclosed which involves contacting a mixture comprising hydrogen fluoride and at least one one starting material selected from haloethanes of the formula CX3191CHX2 and haloethenes of the formula CX2=CX2, where each X is independently selected from the group consisting of F and Cl (provided that no more than four of X are F), with a fluorination catalyst in a reaction zone to produce a product mixture comprising HF, HCl, pentafluoroethane, underfluorinated halogenated hydrocarbon intermediates and less than 0.2 mole percent chloropentafluoroethane based on the total moles of halogenated hydrocarbons in the product mixture. The process is characterized by the fluorination catalyst comprising (i) a crystalline cobalt-substituted alpha-chromium oxide where from about 0.05 atom % to about 6 atom % of the chromium atoms in the alpha-chromium oxide lattice are replaced by trivalent cobalt (Co+3) and/or (ii) a fluorinated crystalline oxide of (i).
- -
-
-
- Process for producing 1,1,1,2,2-pentafluoroethane
-
A process for producing 1,1,1,2,2-pentafluoroethane by fluorinating with hydrogen fluoride at least one of 2,2-dichloro-1,1,1-trifluoroethane and 2-chloro-1,1,1,2-tetrafluoroethane as a starting material, the process being characterized by separating the reaction mixture resulting from the fluorination into a product portion A mainly containing 1,1,1,2,2-pentafluoroethane and a product portion B mainly containing 2,2-dichloro-1,1,1-trifluoroethane, 2-chloro-1,1,1,2-tetrafluoroethane and hydrogen fluoride, removing a fraction mainly containing 2,2-dichloro-1,1,1,2-tetrafluoroethane from the product portion B, and recycling the rest of the product portion B as part of feedstocks for fluorination. According to the process of the invention, the amount of CFC-115 contained in the target HFC-125 can be remarkably reduced through a simplified procedure.
- -
-
Page column 5-7
(2008/06/13)
-
- The behaviour of chlorofluoroethanes on β-aluminium(III) fluoride: A [ 36Cl ] radiotracer study
-
A [36Cl] radiotracer study of the behaviour of 1,1,2-trichlorotrifluoroethane on β-aluminium(III) fluoride at elevated temperature indicates that the isomerisation of CCl2FCClF2 to CCl3CF3 occurs by an intramolecular process. Isomerisation is followed by dismutation of CCl3CF3 to give CCl2FCF3 and CCl3CClF2. In neither reaction, surface Al-Cl groups are formed. The compound CCl3CClF2 undergoes further reaction, readily, apparently also via dismutation processes.
- Bozorgzadeh, Hamid,Kemnitz, Erhard,Nickkho-Amiry, Mahmood,Skapin, Toma?,Tate, Graeme D.,Winfield, John M.
-
p. 225 - 232
(2007/10/03)
-
- Conversion of 1,1,2-trichlorotrifluoroethane to 1,1,1-trichlorotrifluoroethane and 1,1-dichlorotetrafluoroethane over aluminium-based catalysts
-
Conversion of CCl2FCClF2 to CCl2FCF3 is achieved in the temperature range, 593-713 K, under flow conditions by using the catalysts, β-AlF3 or γ-alumina, prefluorinated with CCl2F2/sub
- Bozorgzadeh,Kemnitz,Nickkho-Amiry,Skapin,Winfield
-
-
- Synthesis of functionalized polyfluoroalkyl hypochlorites and fluoroxy compounds and their reactions with some fluoroalkenes
-
Several new polyfluoroalkyl hypochlorites and fluoroxy compounds containing Cl, H and Br in the alkyl group have been prepared and characterized by 19F NMR, 1H NMR and IR spectroscopies and by their reactions with fluoroalkenes to produce new polyfluoroethers.The novel compounds are prepared by the CsF-catalyzed addition of F2 or ClF to the C=O bond in CF3C(O)CF2Cl, ClCF2C(O)CF2Cl, and their derivatives HCF2C(O)CF3 and HCF2C(O)CF2Cl.Compounds containing an α-CF3 group exhibit enhanced thermal stability.New fluoroxy compounds and hypochlorites have also been prepared from the acid fluorides CF3-CFX-C(O)F (X = Cl, Br), which are obtained by the ring-opening reaction of hexafluoropropene oxide with (CH3)3SiCl, LiBr and (C2H5)3SiBr.These -OX compounds behave similarly to previously known materials with two α-F atoms, decomposing quickly at room temperature to COF2 and haloalkanes.
- Randolph, Bruce B.,DesMarteau, Darryl D.
-
p. 129 - 150
(2007/10/02)
-
- Kinetics and Mechanism of the Thermal Reaction between Trifluoromethylhypofluorite and 1,1-Dichlorodifluoroethylene
-
The thermal addition of CF3OF to CF2CCl2 has been studied between -7.0 and 29.7 deg C.The pressure of CF3OF was varied between 6.4 and 196.7 Torr and that of CF2CCl2 between 5.4 and 203 Torr.CF3CCl2F, CF3O(CF2CCl2)F and CF3O(CF2CCl2)iOCF3, where i = 2,3. . .n, were the products.Above 110 Torr of olefin, non-volatile condensate appeared.The reaction was homogeneous and not affected by the total pressure or the presence of an inert gas.Introducing a few Torr of O2 to the reaction system an instantaneous oxidation of CF2CCl2 to CF2ClC(O)Cl occurred.Higher amounts of O2 led to explosion with conversion of both reactant molecules.The basic steps of the reaction were: generation of radicals CF3O. and CF3CCl2. in the bimolecular process between CF3OF and CF2CCl2 (rate constant k1), generation of telomeric radicals by addition of CF3O. to CF2CCl2, abstraction of fluorine atoms from CF3OF by CF3CCl2. and by CF3O(CF2CCl2). (rate constant k4), chain propagation by further successive addition of telomeric radicals to another molecule of olefin (k5) and recombination of telomeric radicals.The following values of the rate constants were obtained: k1 = (5.0+/-1.0)106exp(-9.7+/-0.9 kcal*mol-1/RT)l*mol-1s-1, k4 = (2.6+/-0.5)107exp(-3.1+/-0.6 kcal*mol-1/RT)l*mol-1s-1, k5 = (1.7+/-0.4)105exp(-2.5+/-0.5 kcal*mol-1/RT)l*mol-1s-1. - Keywords: CF3OF, thermal reaction with CCl2CF2 / CCl2CF2, thermal reaction with CF3OF / Trifluoromethylhypofluorite, addition to 1,1-dichlorodifluoroethylene / 1,1-Dichlorodifluoroethylene, reaction with trifluoromethylhypofluorite
- Santos Afonso, M. dos,Czarnowski, J.
-
-
- THE INFRARED SPECTRA OF GASEOUS 1,1,3,3-TETRACHLOROTETRAFLUORO-4-(TRIFLUOROMETHYLDIOXY)BUTYL TRIFLUOROMETHYL ETHER AND 1,1,3,3-TETRACHLOROTETRAFLUORO-1,4-BIS(TRIFLUOROMETHOXY)BUTANE
-
1,1,3,3-Tetrachlorotetrafluoro-4-(trifluoromethyldioxy)butyl trifluoromethyl ether, CF3O(CF2CCl2)2O2CF3, was formed as one of the products in the reaction of CF3O3CF3 with CF2CCl2 at 322.6 - 342.5 K.It was isolated by fractional condensation between 213 and 243 K and characterized by molecular weight determination and 19F NMR spectrum. 1,1,3,3-Tetrachlorotetrafluoro-1,4-bis(trifluoromethoxy)butane, CF3O(CF2CCl2)2OCF3, was condensed as residue at 193 K from the reaction of CF3OF with CF2CCl2 at 266 - 302.7 K, when / 0.5.It was characterized by gas chromatography and molecular weight determination.The infrared spectra of both compounds are given, providing additional support for their characterization.
- Czarnowski, Juana
-
-
- RADIOTRACERS IN FLUORINE CHEMISTRY. PART IX FLUORINATION OF CHLOROFLUOROETHANES BY CHROMIA CATALYSTS TREATED WITH HYDROGEN FLUORIDE OR HYDROGEN -FLUORIDE
-
Passage of dichlorotetrafluoroethane isomers or 1,1,2-trichloro-1,2,2-trifluoroethane at temperatures >/= 623 K over chromia catalysts, previously treated with hydrogen fluoride at 623 K, leads to the formation of fluorinated and chlorinated products.Incorporation of fluorine-18 radioactivity in the products is observed when hydrogen -fluoride is used in the catalyst pretreatment, indicating the involvement of a surface fluorinecontaining species.The reactions observed are described in terms of series of F-for-Cl and Cl-for-F halogen exchange reactions occurring at the catalyst surface.
- Kijowski, Jerzy,Webb, Geoffrey,Winfield, John W.
-
p. 213 - 230
(2007/10/02)
-
- Comparison of the Reactivity of CF3OX (X = Cl, F) with Some Simple Alkenes
-
Reactions of CF3OX (X = Cl, F) with a variety of simple alkenes were carried out to compare the regio- and stereoselectivity of the additions to carbon-carbon double bonds.The observed addition products with CF3OCl are consistent with an electrophilic syn addition.With CF3OF the observed products indicate a different regioselectivity and low stereoselectivity, consistent with a free-radical addition.
- Johri, Kamalesh K.,DesMarteau, Darryl D.
-
p. 242 - 250
(2007/10/02)
-