- MICROWAVE SPECTRUM, BARRIER TO INTERNAL ROTATION, STRUCTURE, AND DIPOLE MOMENT OF 1,1,1,2-TETRAFLUOROETHANE
-
The microwave spectrum of CF3CH2F has been studied in the 8 to 26 GHz region, with b-type, Q- and R-branch transitions being assigned for the ground vibrational state and first excited torsional state.Relative intensity measurements give a torsional frequency of 108 +/- 18 cm-1, which lead to a barrier to internal rotation V3 = 3.3 +/- 0.8 kcal mol-1.The dipole moments determined from the observed first-second order Stark effect are μa = 0.411 +/- 0.009 D, μb = 1.75 +/- 0.22 D, and μtotal = 1.80 +/- 0.22 D.Observed moments of intertia suggest that the CF3 group is not symmetrical or its axis and the C-C bond are not collinear.The distance rF'...F' is obtained 2.1594 +/- 0.0006 Angstroem, where F' refers to the outer plane fluorine atoms in the CF3 group.
- Ogata, Teruhiko,Miki, Yasuhiro
-
-
Read Online
- Electroreduction of a Chlorofluoroethane on a Solid Polymer Electrolyte Composite Electrode
-
The dechlorination of 2-chloro-1,1,1,2-tetrafluoroethane (HCFC-124) was carried out electrochemically on a solid polymer electrolyte composite electrode (Pd-Neosepta).As the sole product 1,1,1,2-tetrafluoroethane (HFC-134a) was obtained.Irradiation with light of a xenon arc lamp enhanced the dissociation of C-Cl bond of the reactant adsorbed on Pd, resulting in an increase in the rate for HFC-134a formation.
- Inaba, Minoru,Sawai, Ken,Ogumi, Zempachi,Takehara, Zen-ichiro
-
-
Read Online
- Effect of acid strength of co-precipitated chromia/alumina catalyst on the conversion and selectivity in the fluorination of 2-chloro-1,1,1-trifluoroethane to 1,1,1,2-tetrafluoroethane
-
Different fluorinated catalysts based on co-precipitated Cr2O3/Al2O3 and doped with compounds of Zn and/or Mg are prepared and their total acidity determined by TPD of ammonia. The influence of acidity of the above catalysts on the conversion and selectivity in the fluorination of HCFC-133a to give HFC-134a was studied. It was found that the selectivity for HFC-134a increases with a fall in the relative percentage of strong acid centres.
- Madhusudana Rao, Jampani,Shanthan Rao,Vijayakumar,Venkata Rao,Narsaiah,Narayan Reddy,Leela Krishna,Srinivas,Radhakrishnan,Patil
-
-
Read Online
- Effect of calcination temperature on CrOx-Y2O3 catalysts for fluorination of 2-chloro-1,1,1-trifluoroethane to 1,1,1,2-tetrafluoroethane
-
A series of CrOx-Y2O3 catalysts were prepared by a deposition-precipitation method and tested for the fluorination of 2-chloro-1,1,1-trifluoroethane (CF3CH2Cl) to synthesize 1,1,1,2-tetrafluoroethane (CF3CH2F). The highest activity was obtained on a pre-fluorinated catalyst calcined at 400 °C, with 19% of CF3CH2Cl conversion at 320 °C. The effect of the calcination temperature on the CrOx species was investigated. X-ray diffraction and Raman results indicated that the CrOx species (Cr(VI)) were well dispersed on the catalyst surface when the catalyst was calcined at 400 °C. With increasing calcination temperature, most of the CrOx species changed from high oxidation state Cr(VI) to low oxidation state Cr(V) or Cr(III) species, which resulted in difficulty in pre-fluorination of the catalyst. It was also found that the CrFx, CrOxFy or Cr(OH)xFy phases originated from high oxidation state Cr(VI) species were the active sites for the fluorination reaction.
- He, Jun,Xie, Guan-Qun,Lu, Ji-Qing,Qian, Lin,Zhang, Xue-Liang,Fang, Ping,Pu, Zhi-Ying,Luo, Meng-Fei
-
-
Read Online
- Efficient regioselective labelling of the CFC alternative 1,1,1,2-tetrafluoroethane (HFC-134a) with fluorine-18
-
Efficient chemistry is described for the regioselective labelling of the CFC alternative 1,1,1,2-tetrafluoroethane with cyclotron-produced positron-emitting fluorine-18 (t1/2 = 109.7 min). 1,1,1,2-Tetrafluoroethane was prepared by nucleophilic addition of no-carrier-added fluoride to trifluoroethylene and 1,1,1,2-tetrafluoroethane by nucleophilic displacement of tosylate with fluoride in 2,2,2-trifluoroethyl p-toluenesulphonate.Each reaction was mediated by a potassium cation-Kryptofix 2.2.2 complex, with or without acetonitrile as solvent, in a sealed glassy carbon vessel.The selectivities were 97.2 +/- 0.4percent for labelling in the 1-position by nucleophilic addition and 91.2 +/- 1.2percent for labelling in the 2-position by nucleophilic substitution.GC separation afforded each labelled tetrafluoroethane in high radiochemical purity (>99.995percent) and high chemical purity (>99.6percent).Specific radioactivities of about 37 MBq (1 mCi) per μmol were obtained.Each synthesis was fully automated to cope safely with the high initial radioactivity and delivered purified product within one physical half-life of the fluorine-18.The products are suitable for pharmacokinetic studies in man. - Keywords: Regioselective labelling; 1,1,1,2-Tetrafluoroethane; Fluorine-18; Nucleophilic addition; Nucleophilic substitution; Mass spectrometry
- Aigbirhio, Franklin I.,Pike, Victor W.,Waters, Stephen L.,Tanner, Richard J. N.
-
-
Read Online
- METHOD OF PRODUCING HALIDE
-
PROBLEM TO BE SOLVED: To provide a novel method of producing a halide. SOLUTION: A method of producing a halide comprises reacting a halogen with a compound of general formula (1) in the figure, where X and Y each independently represent H, F or CF3. The halide is an unsaturated halide or a saturated halide. SELECTED DRAWING: None COPYRIGHT: (C)2021,JPOandINPIT
- -
-
Paragraph 0054; 0058
(2021/01/09)
-
- CATALYST AND PROCESS USING THE CATALYST FOR MANUFACTURING FLUORINATED HYDROCARBONS
-
A catalyst comprising one or more metal oxides, wherein the catalyst has a total pore volume equal to or greater than 0.3 cm3/g and a mean pore diameter greater than or equal to 90 ?, where in the pore volume is measured using N2 adsorption porosimetry and the mean pore diameter is measured using N2 BET adsorption porosimetry.
- -
-
Page/Page column 10; 11; 12; 17
(2018/03/28)
-
- CATALYST AND PROCESS USING THE CATALYST FOR MANUFACTURING FLUORINATED HYDROCARBONS
-
A catalyst comprising chromia and at least one additional metal or compound thereof and wherein the catalyst has a total pore volume of greater than 0.3 cm3/g and the mean pore diameter is greater than or equal to 90 ?, wherein the total pore volume is measured by N2 adsorption porosimetry and the mean pore diameter is measured by N2 BET adsorption porosimetry, and wherein the at least one additional metal is selected from Li, Na, K, Ca, Mg, Cs, Sc, Al, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Ru, Co, Rh, Ir, Ni, Pd, In, Pt, Cu, Ag, Au, Zn, La, Ce and mixtures thereof.
- -
-
Page/Page column 11-13
(2018/03/28)
-
- Device and method for preparing 1,1,1,2-tetrafluoroethane
-
The invention discloses a device for preparing 1,1,1,2-tetrafluoroethane. The device comprises a preheater, a vertically-installed tubular reactor, a vertically-installed molten salt furnace, a buffer tank, a water scrubber, an alkaline tower, a drying tower and a rectifying tower; the preheater, the tubular reactor, the buffer tank, the water scrubber, the alkaline tower, the drying tower and the rectifying tower are sequentially connected, the tubular reactor comprises a reactor body, an upper sealing end and a lower sealing end, the upper sealing end and the lower sealing end are arranged at the two ends of the reactor body, and the reactor body penetrates the molten salt furnace. The invention further discloses a method for preparing the 1,1,1,2-tetrafluoroethane with the device. The device has the beneficial effects of being simple in structure, stable in operation, efficient, economical and long in running period.
- -
-
Paragraph 0023-0024
(2017/06/20)
-
- Method for preparing fluorinated compound CH2F-R (R is H or CF3) through difluoromethane pyrolysis
-
The invention discloses a method for preparing a fluorinated compound CH2F-R (R is H or CF3) through difluoromethane pyrolysis. According the method, the fluorinated compound is obtained through a gas-phase reaction between difluoromethane and CH4, NH3, H2O or H under the circumstance that no catalyst exists. The following reaction conditions of the method are achieved: the reaction pressure is 0.1-1.5 MPa; the reaction temperature is 700-1000 DEG C; the mole ratio of difluoromethane to any one or more of CH4, NH3, H2O and H is 1:(0-40); and the residence time is 0.1-50 s. The method disclosed by the invention has the advantages that the raw material, namely difluoromethane, is easy to obtain; no catalyst needs to use; the operation and the control are easy; and the experimental repeatability is high.
- -
-
Paragraph 0034-0037
(2017/05/18)
-
- METHOD OF PRODUCING TRIFLUOROETHYLENE
-
PROBLEM TO BE SOLVED: To provide an economically advantageous method for producing industrially useful trifluoroethylene with high productivity by using easily available HCFC-124 as raw material while not using any catalyst. SOLUTION: A method of producing trifluoroethylene includes the step of bringing a reductive compound and 1,1,1,2-tetrafluoro-2-chloroethane into contact with each other, without using any catalyst, at a temperature of 400-1200°C. COPYRIGHT: (C)2016,JPO&INPIT
- -
-
Paragraph 0056-0058; 0071
(2017/01/02)
-
- Examples of catalytic and selective routes for fluorinated building blocks
-
Examples are presented for the catalytic fluorination of chlorinated starting materials in order to produce building blocks or HFCs. The fluorination of CF3CH2Cl, of CCl2=CCl2, of trichloromethoxylbenzenes and trichloromethoxybenzene involving nucleophilic substitution are reported. In all cases, HF was the fluorinating agent. Depending on the chlorinated substrate and the degree of fluorination required, liquid- or gas-phase processes were involved. Usually, catalysts were SbCl 5 in liquid phase and chromium oxide in gas phase. In the presence of SbCl5, at 90 °C under an initial pressure of 10 bar, the fluorination of CCl2=CCl2 leads mainly to the formation of CClF2CHCl2, and the active catalyst is an antimony mixed halide (SbCl3F2). In the same way, the presence of SbCl5 favored the formation of 1-trifluoromethyl-3- trichloromethylbenzene from bis-1,3-trichloromethylbenzene at low temperature (50 °C) and in the presence of a low amount of HF. Moreover, trichloromethoxybenzene was totally transformed into trifluoromethoxybenzene. At 380 °C and at atmospheric pressure, the transformation of CF 3CH2Cl into CF3CH2F was favored over chromium oxide-based catalyst modified by zinc (corresponding to a (Zn/Zn + Cr) molar ratio of 0.22).
- Brunet, Sylvette
-
p. 1067 - 1071
(2014/11/27)
-
- CATALYST AND PROCESS USING THE CATALYST
-
A new chromium-containing fluorination catalyst is described. The catalyst comprises an amount of zinc that promotes activity. The zinc is contained in aggregates which have a size across their largest dimension of up to 1 micron. The aggregates are distributed throughout at least the surface region of the catalyst and greater than 40 weight % of the aggregates contain a concentration of zinc that is within ±1 weight % of the modal concentration of zinc in those aggregates.
- -
-
Page/Page column 7
(2012/05/20)
-
- Catalytic fluorination of 1,1,1-trifluoro-2-chloro-ethane in the presence of oxygen over chromium based catalyst doped or not by zinc supported over partially fluorinated alumina
-
The addition of zinc in low amount to chromium based catalyst supported over partially fluorinated alumina has a positive effect for the fluorination reaction of CF3CH2Cl in the presence of dioxygen in order to prevent the catalyst deactivation. However, under these operating conditions, the Deacon reaction by reaction with HCl produced by Cl/F exchanges could be involved. The formation of various by-products was observed corresponding to the addition of HCl or Cl2 into halogenated double bonds.
- Loustaunau,Fayolle-Romelaer,Celerier,Brunet
-
experimental part
p. 1262 - 1265
(2011/12/21)
-
- Explored routes to unknown polyfluoroorganyliodine hexafluorides, R FIF6
-
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.
-
experimental part
p. 1000 - 1006
(2010/11/16)
-
- Investigation of CF2 carbene on the surface of activated charcoal in the synthesis of trifluoroiodomethane via vapor-phase catalytic reaction
-
This paper investigates the synthetic mechanism of trifluoroiodomethane (CF3I) in the reaction of trifluoromethane and iodine via vapor-phase catalytic reaction. It is suggested that CF2 carbene is the key intermediate and is formed in the pyrolysis process of CHF3 at high temperature. However, in pyrolysis of CHF3 under activated charcoal (AC) existing conditions, no C2F4 was detected. H2 and 2-methyl-2-butene could not trap the CF2 carbene. When treating the remained compounds on the used AC with H2, CH4 is formed on the process. It is proposed that CF2 carbene combines with AC strongly and transfers into CF3 radical on heat. In addition, it is found that the AC is not only the catalyst supporter to form CF3I, but also a co-catalyst to promote the formation of CF2 carbene and CF3 radical.
- Yang, Guang-Cheng,Lei, Shi,Pan, Ren-Ming,Quan, Heng-Dao
-
experimental part
p. 231 - 235
(2009/08/07)
-
- Process for the preparation of fluorinated halocarbons
-
A improved process is described for the preparation of a substantially pure, liquefied stream of 1,1,1,2-tetrafluoroethane by the catalyzed reaction of trichloroethylene with hydrogen fluoride to form the intermediate 2-chloro-1,1,1-trifluoroethane and then reacting said intermediate 2-chloro-1,1,1-trifluoroethane with hydrogen fluoride, in the presence of a hydrofluorination catalyst to form a reaction stream containing 1,1,1,2-tetrafluoroethane. The improvement comprises liquefying the by-product hydrogen chloride formed in the preparation of the intermediate 2-chloro-1,1,1-trifluoroethane and countercurrently passing said liquefied hydrogen chloride thru the reaction stream containing 1,1,1,2-tetrafluoroethane thereby forming a substantially pure, liquefied stream of 1,1,1,2-tetrafluoroethane and an effluent comprising gaseous hydrogen chloride.
- -
-
Page/Page column 4
(2008/12/07)
-
- High pressure catalyst activation method and catalyst produced thereby
-
A process for the activation of a fluorination catalyst in which a catalyst precursor compound, supported or unsupported is first dried and thereafter activated by exposure to an activating agent at a pressure greater that about 100 psig and a temperature grater than about 100° C. The process is particularly suited to the activation of chromium (III) compounds, such as Cr2O3. The resulted dry, high-pressure activated catalyst was found to provide increase fluorination conversion, with higher selectivity of the desired product.
- -
-
Page/Page column 3-4
(2008/06/13)
-
- AZEOTROPE COMPOSITIONS COMPRISING NONAFLUOROPENTENE AND HYDROGEN FLUORIDE AND USES THEREOF
-
Disclosed herein are azeotrope compositions comprising 1,2,3,3,3-pentafluoropropene and hydrogen fluoride. The azeotrope compositions are useful in processes to produce and in processes to purify 1,2,3,3,3-pentafluoropropene. Additionally, disclosed herein are azeotrope and near-azeotrope compositions comprising 1,1,1,2,3,4,4,5,5,5-decafluoropentane and hydrogen fluoride.
- -
-
Page/Page column 21-22
(2008/06/13)
-
- Methane and methyl chloride as selective reducing agent in the transformation of hydrochlorofluorocarbons or chlorofluorocarbons to hydrofluorocarbons
-
A gas phase reaction process for producing a hydrofluorocarbon from a hydrochlorofluorocarbon or chlorofluorocarbon reactant by contacting, in the presence of a catalyst, the hydrochlorofluorocarbon or chlorofluorocarbon reactant with a reducing agent selected from methane, methyl chloride and mixtures thereof, to produce the hydrofluorocarbon.
- -
-
Page/Page column 6
(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)
-
- 1,1,3,3,3-Pentafluoropropene secondary amine adducts new selective fluorinating agents
-
Addition of secondary amine SA (dimethylamine DMA, diethylamine DEA, pyrrolidine Pyr, piperidine Pip, morpholine Mor) to pentafluoropropene PFP gives rise to generation of mixtures of two products (1-dialkylamine-1,3,3,3-tetrafluoropropene and N,N-dialkyl-1,1,3,3,3-pentafluoropropylamine) in different ratios. Those reaction mixtures, however, were found to be efficient fluorinating agents replacing hydroxyl groups in alcohols into fluorine. In general, they react with alcohols yielding corresponding fluorides, equimolar amounts of appropriate 3,3,3-trifluoropropionamide and hydrogen fluoride. Aliphatic primary alcohols including octanol and benzylic alcohol yield only alkyl fluorides. The secondary and tertiary alcohols, beside the desired fluorides, give usually considerably amount of alkenes.
- Koroniak, Henryk,Walkowiak, Justyna,Grys, Krzysztof,Rajchel, Andrzej,Alty, Adam,Du Boisson, Rick
-
p. 1245 - 1251
(2008/09/20)
-
- NOVEL CATALYTIC METHOD FOR THE PRODUCTION OF FLUOROALKYLENES FROM CHLOROFLUOROHYDROCARBONS
-
A process for producing a producing a product of the formula: [in-line-formulae]R—CF═CHR1 [/in-line-formulae] wherein R is F or CF3 and R1 is F when R is F and is H when R is CF3 by reacting a reactant of the formula: [in-line-formulae]CF3—R2 [/in-line-formulae] wherein R2 is selected from wherein R3 is H, F or Cl and R4 is H or Cl, in the presence of a suitable catalyst, with a reducing agent selected from methane, methyl chloride and mixtures thereof, in a gas phase reaction.
- -
-
Page/Page column 3; 4
(2008/06/13)
-
- PROCESS FOR PRODUCTION OF 1,1,1,2-TETRAFLUOROETHANE AND/OR PENTAFLUOROETHANE AND APPLICATIONS OF THE SAME
-
A process for producing high purity 1,1,1,2-tetrafluoroethane and/or pentafluoroethane by the step of purifying a crude product obtained by reacting trichloroethylene and/or tetrachloroethylene with hydrogen fluoride comprised of a main product including 1,1,1,2-tetrafluoroethane and/or pentafluoroethane, hydrogen fluoride as an azeotropic component with the main product, and impurity ingredients including at least an unsaturated compound, wherein said purifying step includes a step of bringing a mixture obtained by newly adding hydrogen fluoride into said crude product into contact with a fluorination catalyst in the vapor phase to reducing the content of the unsaturated compound contained in said crude product and a distillation step.
- -
-
Page/Page column 10-16
(2008/06/13)
-
- PROCESS FOR THE PURIFICATION OF (HYDRO)HALOCARBONS
-
A process for treating a composition comprising one or more desired (hydro)halocarbons and one or more undesired sulphur containing impurities so as to reduce the concentration of at least one undesired sulphur containing impurity, the process comprising contacting the composition with an adsorbent comprising an acid stable molecular sieve having a pore size of from 2 to l0? and/or an activated carbon.
- -
-
-
- Method for purifying tetrachloroethylene and process for producing hydrofluorocarbons
-
Tetrachloroethylene containing a stabilizer is contacted with a zeolite having an average pore size of 3.4 to 11 ? and/or a carbonaceous adsorbent having an average pore size of 3.4 to 11 ? in a liquid phase to obtain a high purity tetrachloroethylene. A halogenated alkene and/or a halogenated alkane are reacted with hydrogen fluoride in the presence of a fluorination catalyst to produce a first hydrofluorocarbon, a halogenated alkene and/or a halogenated alkane are reacted with hydrogen fluoride in the presence of a fluorination catalyst to produce a second hydrofluorocarbon, and the products are joined and then distilled to obtain the first and second hydrofluorocarbons.
- -
-
Page/Page column 7-10
(2008/06/13)
-
- A study of trichloroethylene hydrofluorination using a kinetic model
-
The kinetic features of catalytic hydrofluorination of trichloroethylene and 2-chloro-1,1,1-trifluoroethane on chromium fluoride/magnesium fluoride catalyst were studied. The effect of pressure and addition of various components of the reaction mixture at the reactor inlet was studied using the developed model.
- Dmitriev,Trukshin,Smykalov
-
p. 771 - 776
(2007/10/03)
-
- Chloropentafluoroethane hydrodechlorination over tungsten carbides: Influence of surface stoichiometry
-
The relationship between the mode of activation and the catalytic properties of tungsten carbides was studied. Tungsten carbides were prepared by temperature-programmed reaction of WO3 with methane/hydrogen mixture and activated according to several thermal treatments by varying the temperature or the feed composition. The acid-base characteristic increased with the extent of decarburization of the surface. The surface properties of WC could be adjusted toward the formation of unsaturated compounds or alternatively toward hydrogenolysis compounds. However, the convergence observed in the temperature-programmed selectivity curves, whatever the initial C/W ratio, showed that the sample surfaces reach similar compositions by recarburization during reaction. Such acidic properties were involved in the dehydrohalogenation of chloropentafluoroethane responsible mainly for the formation of unsaturated compounds.
- Granger,Giraudon,Delannoy,Leclercq,Leclercq
-
p. 358 - 362
(2007/10/03)
-
- Synthesis of trifluoroethyl ethers from 2,2,2-trifluoroethyl chloride (HCFC-133a) in high temperature aqueous medium
-
Treatment of 2,2,2-trifluoroethyl chloride (HCFC-133a) with alcohols (phenols) and aqueous KOH in autoclave at 240-280 C gives the corresponding 2,2,2-trifluoroethyl (2-chloro-1,1-difluoroethyl) ethers in good yields.
- Wu, Kai,Chen, Qing-Yun
-
-
- Reactions of oxalyl fluoride with electrophiles
-
The reactions of oxalyl fluoride with electrophiles in the presence of alkali metal fluoride were carried out. In the reaction with CF3CH2OH (Tl = CF3SO2) or CH3CH2OTf, the synthesis of di-
- Murata, Junji,Tamura, Masanori,Sekiya, Akira
-
-
- Fluorination catalyst and process
-
A chromia-based fluorination catalyst in which the chromia is at least partially crystalline and which may contain a zinc or a compound thereof, the production of the catalyst by sintering amorphous chromia and its use in fluorination processes.
- -
-
-
- Pyrolyses of chlorodifluoromethane and trifluoromethane in the presence of hydrogen. Mechanism and optimization of reaction conditions
-
When CHC1F2 and CHF3 are subjected to high-temperature, gas-phase flow pyrolysis in the presence of H2, they are converted, via a free radical chain mechanism, to CH2F2, CHF2CHF2, and CF3CH2F in good yield. Optimal conditions for pyrolysis of CHC1F2 involve a high conversion (92%) at 650 °C with an observed yield of products = 18, 17, and 28%, respectively, whereas optimal conditions for CHF3 involve a low conversion (24%) at 775 °C, but a higher yield of products (26, 6, and 39%, respectively).
- Romelaer,Kruger,Baker,Dolbier Jr.
-
p. 6767 - 6772
(2007/10/03)
-
- Gas-phase fluorination of fluoroethanes with elemental fluorine
-
Scientific basis for industrial gas-phase fluorination of fluoroethanes with elemental fluorine allowing production of higher-fluorinated fluoroethanes from lower-fluorinated compounds is developed. 2001 MAIK "Nauka/Interperiodica".
- Pashkevich,Mukhortov,Alekseev,Asovich,Rozhdestvenskaya
-
p. 1151 - 1155
(2007/10/03)
-
- Thermal isomerization of 1,1,2,2-tetrafluoroethane (FC-134) to 1,1,1,2-tetrafluoroethane (FC-134a) in the presence of hydrogen
-
The mechanism of the high-temperature, gas-phase isomerization of 1,1,2,2-tetrafluoroethane (FC-134) to 1,1,1,2-tetrafluoroethane (FC-134a) in the presence of H2 has been explored both experimentally and computationally. Studies of the impact of temperature, H2/FC-134 ratio, and contact time on conversion and yield, as well as a study of deuterium incorporation when D2 was used in place of H2, led to the conclusion that a free radical chain mechanism involving rearrangement of CHF2CF2· to CF3CHF· is involved.
- Romelaer,Baker,Dolbier Jr.
-
p. 6773 - 6777
(2007/10/03)
-
- Preparation of 1,1,1,2-tetrafluoroethane by the vapor-phase catalytic reaction of 1,1,1-trifluoro-2-chloroethane with anhydrous hydrogen fluoride
-
1,1,1,2-Tetrafluoroethane was prepared in 97% selectivity by the vapor-phase catalytic reaction of 1,1,1-trifluoro-2-chloroethane with anhydrous hydrogen fluoride (AHF) over a metal fluoride catalyst (CrF3 and CoF2) supported on porous aluminum fluoride (PAF). The relationship between the crystalline phase transition of porous aluminum fluoride and temperature from 100 to 640°C was investigated by X-ray diffraction.
- Quan, Heng-Dao,Yang, Hui-E,Li, Zhong,Ren, Jian-Zhang,Li, Hui-Li
-
p. 193 - 199
(2007/10/03)
-
- Electrophilic, catalytic alkylation of polyfluoroolefins by some fluoroalkanes
-
New data are presented on the antimony pentafluoride catalyzed reaction of hydrofluorocarbons such as CH3F, CH2F2, CH3CHF2 and RfCH2CH2F with fluoroolefins. The condensation of CH2F2 and fluoroolefins CF2=CFX (X=F, CF3) proceeds under mild conditions producing the corresponding propanes FCH2CFXCF3 in moderate to high yield. Under similar conditions methyl fluoride reacts with tetrafluoroethylene giving CH3CF2CF3. However, a complex mixture of products forms in the analogous reaction with hexafluoropropene. The structures of the products of the reactions of CH3CHF2 and tetrafluoroethylene and F-butylethylene were determined.
- Belen'Kii,Petrov,Resnick
-
-
- Hydrodechlorination of 1,1-dichlorotetrafluoroethane over Pd/Al2O3 catalyst. Effect of hydrogen pressure and catalyst pretreatment
-
An alumina-supported palladium catalyst has been studied in CF3CFCl2 hydrodechlorination at 100°C using a static-circulation system. At higher partial pressures of H2, when the existence of the β-PdH phase is awaited, the reaction occurs similarly as at lower hydrogen pressures. This indicates that either the β-PdH formation does not have any special effect on active sites of this reaction, or the presence of CF3CFCl2 in the system inhibits this phase transformation. Various pretreatments of the 2 wt.% Pd/Al2O3 influence markedly its catalytic behavior. In particular, reoxidation and subsequent low temperature reduction of the catalyst, prereduced at 600°C, generates a very high activity, however, the selectivity towards CF3CFH2 is not much altered.
- Karpinski,D'Itri
-
p. 1421 - 1452
(2007/10/03)
-
- Turnover Rate, Reaction Order, and Elementary Steps for the Hydrodechlorination of Chlorofluorocarbon Compounds on Palladium Catalysts
-
The rates of hydrodechlorination catalyzed by Pd supported on carbon for four chlorofluorocarbons spanned a range of 7 orders of magnitude. The rates scaled up to the bond strength of the carbon-chlorine bond for the gas-phase reactant. This finding demonstrates that the rate-determining step involves the scission of the C-Cl bond and suggests, through Polanyi and linear free-energy relationships, that rates for other compounds can be estimated if the C-Cl bond strength is known. The reaction orders for the most abundant products are approximately first-order for the chlorine-containing compound, half-order in H2, and inverse first-order in HCl. The reaction steps consistent with these orders include a rate-determining step involving the adsorption of the chlorofluorocarbon to a single site (which could be a single surface palladium atom) and equilibrated steps between gas-phase H2, gas-phase HCl, and adsorbed hydrogen and chlorine atoms. The rates on the supported catalysts are comparable to the ones reported before on a Pd foil, indicating that the support does not play a role in the reaction. The product distribution is independent of conversion, implying that the various products are formed from a single visit of the reactant on the surface and not from readsorption of gas-phase products. The four compounds studied were chloropentafluoroethane (CF3-CF2Cl), 2-chloro-1,1,1,2-tetrafluoroethane (CF3-CFClH), 1,1-dichlorotetrafluoroethane (CF3-CFCl2), and 1,1,1-trichloro-2,2,2-trifluoroethane (CF3-CCl3).
- Thompson,Rioux,Chen,Ribeiro
-
p. 3067 - 3077
(2007/10/03)
-
- Catalytic fluorination of trichloroethene by anhydrous hydrogen fluoride in the presence of fluorinated chromia under static conditions. Synthesis of [18F]-labelled CF3CH2F and [36Cl]-labelled CF3CH2Cl. Catalytic dehydrofluorination of CF3CH2F and CF3CH2Cl
-
Catalytic fluorination of trichloroethene by anhydrous hydrogen fluoride at 653K in the presence of fluorinated amorphous chromia under static conditions leads to a mixture of products in which partially halogenated olefins predominate. These are converted to mixtures containing CF3CH2F and CF3CH2Cl by a second fluorination using fresh catalyst. The results of product analyses from reactions carried out under various conditions have been used to design a synthesis of [18F]-CF3CH2F from CCl2CHCl. It is proposed that [18F] labelling occurs via direct [18F]- for [19F] exchange rather than by a dehydrofluorination/hydrofluorination route. [36Cl]-labelled CF3CH2Cl is readily prepared from CF3CH2F and H36Cl in the presence of chromia catalysts. Enthalpies of dehydrofluorination of CF3CH2F and CF3CH2Cl in the vapour phase have been computed.Non-SI units employed: ?=10-10m; a.u.≈4.36×10-18 J≈6.27089×102kcalmol-1.1
- Baker, Alan W.,Bonniface, David,Klap?tke, Thomas M.,Nicol, Irene,Scott, John D.,Scott, William D.S.,Spence, Ronald R.,Watson, Michael J.,Webb, Geoffrey,Winfield, John M.
-
p. 279 - 284
(2007/10/03)
-
- Hydrodechlorination of 1,1-dichlorotetrafluoroethane and dichlorodifluoromethane catalyzed by Pd on fluorinated aluminas: The role of support material
-
The gas phase hydrodechlorination of CF3CFCl2 to CF3CFH2 and CF2Cl2 to CF2H2 catalyzed by Pd supported on Al2O3, a series of fluorinated Al2O3, and AlF3 was investigated. A combination of reaction kinetics investigations and characterization by in situ FTIR spectroscopy has been performed. It has been found that for reactions involving CF3CFCl2, all catalysts exhibit a rapid and significant decrease in activity; however, little change in activity with time on stream occurs with CF2Cl2. FTIR investigations suggest the occurrence of direct reaction between the CFC and the support material, which results in the consumption of hydroxyl groups during the early stages of reaction. The effect of fluorination of support on catalytic behavior of Pd is discussed.
- Early, Kintu,Kovalchuk, Vladimir I.,Lonyi, Ferenc,Deshmukh, Subodh,D'Itri, Julie L.
-
p. 219 - 227
(2007/10/03)
-
- vic-difluorination of fluoroalkenes with xenon difiuoride: The effect of fluorine substituents on the reaction of alkenes with xenon difluoride
-
vic-Difluorination proceeds by the reaction of fluoroalkenes with xenon difluoride to afford the corresponding fluorinated compounds. From the reaction with polyfluoroalkenes, the products are obtained in high to excellent yields. In this reaction, the fluorine atom substituent of alkene stabilizes the cation intermediate and suppresses side-reactions such as rearrangement.
- Tamura, Masanori,Quan, Heng-Dao,Sekiya, Akira
-
p. 3151 - 3153
(2007/10/03)
-
- Generation of radical species in surface reactions of chlorohydrocarbons and chlorocarbons with fluorinated gallium(III) oxide or indium(III) oxide
-
The reactions of C1 and C2 chlorohydrocarbons and chlorocarbons have been studied with the Lewis acid catalysts fluorinated gallium(III) oxide and fluorinated indium(III) oxide, respectively. Product analysis shows chlorine-for-fluorine exchange reactions together with the formation of 2-methylpropane and its chlorinated analogues 2-chloromethyl-1,3-dichloropropane and 2-chloromethyl-1,2,3-trichloropropane. Reactivities of the chlorohydrocarbon probe molecules show fluorinated gallium(III) oxide to be a stronger Lewis acid than fluorinated indium(III) oxide. The formation of the symmetrical butyl compounds is consistent with the generation of surface radical species and is also consistent with a 1,2-migration mechanism operating within radical moieties at the Lewis acid surface.
- Thomson
-
p. 1881 - 1885
(2007/10/03)
-
- Selective reduction of halopolyfluorocarbons by organosilicon hydrides
-
It is demonstrated that silicon hydrides can be used for reduction of polyfluorinated halocarbons. For example, the reaction between CF3CCl2F and excess triethylsilane, catalyzed by benzoyl peroxide, leads to the formation of a mixture containing CF3CHClF (major), CF3CH2F, and ClSi(C2H5)3. On the other hand, the reaction of chlorofluoroalkanes, containing an internal -CCl2- group readily proceeds with reduction of both chlorines, leading to compounds such as (CF3)2CH2 and CF3CH2C2F5. In contrast to chlorofluoroalkanes, bromofluoroalkanes are much more reactive and reaction with hydrosilane rapidly proceeds without the catalyst at elevated temperature.
- Petrov, Viacheslav A.
-
p. 7294 - 7297
(2007/10/03)
-
- Structure Insensitivity and Effect of Sulfur in the Reaction of Hydrodechlorination of 1,1-Dichlorotetrafluoroethane (CF3-CFCl2 ) over Pd Catalysts
-
The kinetics of the hydrodechlorination of 1,1-dichlorotetrafluoroethane (CFC 114a) was studied on Pd(111), Pd(100), and a Pd foil at atmospheric pressure. The three products formed were CF3-CFH2 (HFC 134a), CF3-CFClH (HCFC 124), and CF3-CH3 (HFC 143a) with selectivities independent of conversion. The single crystals and foil (model catalysts) were studied in an apparatus that permitted the direct transfer of samples between a high pressure cell (1 atm) and an ultrahigh vacuum chamber. The reaction rates were measured in the temperature range of 350 to 470 K. The reaction is not sensitive to the structure of the catalyst, as indicated by the similar turnover rates for all catalysts tested. The reaction is inverse first order in the reaction product HCl on all samples. Sulfur adsorbed on the Pd surface depressed the rates of formation of 134a more strongly than the rates of 124 and 143a.
- Ribeiro,Gerken,Rupprechter,Somorjai,Kellner,Coulston,Manzer,Abrams
-
p. 352 - 357
(2007/10/03)
-
- Catalytic synthesis of 1,1,1,2-tetrafluoroethane from 1,1,1,2-tetrachloroethane - A mechanistic consideration
-
1,1,1,2-Tetrachloroethane and its fluorinated derivatives as well as trichloroethene are fluorinated by hydrogen fluoride in the presence of a pre-conditioned chromia catalyst. The reaction pathways are derived under different conditions. Fluorinated haloalkanes are formed both by dehydrochlorination/hydrofruorination mechanism as well as chlorine/ fluorine exchange mechanism. Thus, beside fluorinated alkanes considerable amounts of haloolefins occur in the product mixture. A survey is given on the reaction pathway showing dependence on the reaction conditions. It is discussed with respect to calculated thermodynamic data. Kinetic and mechanistic investigations of the isomerisation reactions of 1.1.2.2-tetrafluoroethane on a CFC-conditioned chromia catalyst are also presented. The desired 1.1.1.2- tetrafluoroethane can be obtained from its symmetric isomer in the presence of a chromia catalyst conditioned exclusively with chlorine-free fluorocarbons. Mechanistic information is obtained by employing DCl which behaves similar to HF during the consecutive isomerisation reaction of 1.1.2.2- tetrafluoroethane. Thus, it is most probable that dehydrohalogenation/hydrohalogenation processes (elimination/addition mechanism) are mainly responsible for the formation of the haloolefins and halocarbons observed on chromia.
- Kemnitz,Niedersen,Kohne
-
p. 485 - 493
(2007/10/03)
-
- Properties of chromium (III) oxides involved in the catalytic gas phase fluorination of CF3CH2Cl
-
The fluorination of chromium oxides reduces the chromium species on the surface. A low fluorination by HF does not modify the total amount of reversibly oxidizable chromium sites, but increases the strength of these sites. Mobile dioxygen (measured by isotopic exchange) was required to obtain a good fluorination activity. These dioxygen species would be exchanged by HF which is probably active in the fluorination of CF3CH2Cl and would prevent the irreversibly catalyst fluorination.
- Brunet,Boussand,Martin
-
p. 287 - 292
(2007/10/03)
-
- Catalytic hydrodechlorination of 1,1-dichlorotetrafluoroethane by Pd/Al2O3
-
Palladium supported on γ-alumina displays high activity for the hydrodechlorination of 1,1-dichlorotetrafluoroethane. High H2 partial pressures are needed to avoid deactivation, and steady state is obtained after ～5 h time on stream. Under these conditions (H2/CFC feed ratio = 20) the reaction is zero order in H2 partial pressure and positive (0.65) order in 1,1-dichlorotetrafluoroethane partial pressure. Three main products are formed: 1,1,1,2-tetrafluoroethane, 1-chloro-1,2,2,2-tetrafluoroethane, and 1,1,1-trifluoroethane, with approximately 85% selectivity toward the desired CF3CFH2. The apparent activation energies associated with the formation of each product range from 52 to 68 kJ/mol. All three major products have a nonzero rate of formation in the limit of zero conversion, the implication of which is that all are primary products. The kinetics results are consistent with a reaction mechanism involving a carbene intermediate. Variation of the temperature at which the catalyst is prereduced from 300 to 600°C results in an increase in particle size from 11-53 nm and in an increase in the hydrodechlorination TOF from 2.3 to 5.0 s-1.
- Karpinski, Zbigniew,Early, Kintu,D'Itri, Julie L.
-
p. 378 - 386
(2007/10/03)
-
- Advances in trifluoromethylating phosphorus compounds
-
The System CF3IMe3P is re-investigated and Me2PCF3, Me4P+I-, (CF3)2PMe3, Me3PI2, [Me3(CF3)P]+I- are found as products. Using CF3Br/P(NEt2)3 the phosphines R12PCF3 and R1P(CF3)2 (e.g. R1 = Me, iPr, NEt2) can be obtained which are precursors either for phosphoranes (e.g. 1,2λ5σ5-oxaphosphetanes) or phosphonium salts (e.g. [R12(Me)PCF3]+X- or [R1(Me)P(CF3)2X-]. The latter are deprotonated to furnish methylene phosphoranes R12(CH2=)PCF3 or R1(CH2=)P(CF3)2, reactive synthons. From CF3Br/ P(NEt2)3/P(OPh)3 the phosphine P(CF3)3 is available, which turned out to be a potent electrophile. Amido phospites ROP(NEt2)2 and halides R2X (R2= CCl2CF3, X= Cl; R2= CF=CFCF3, X= F; R2= C6F5, X= Br, I; R2= C(CF3)3, X= Br; R2= SCF3, X= CF3) undergo an ARBUZOV reaction.
- Kolomeitsev, Alexander,Goerg, Michaela,Dieckbreder, Uwe,Lork, Enno,Roeschenthaler, Gerd-Volker
-
p. 597 - 600
(2007/10/03)
-
- Mechanistic aspects of the isomerization reactions of 1,1,2,2-tetrafluoroethane on a CFC-conditioned chromia catalyst
-
The mechanism of the isomerization reactions of 1,1,2,2-tetrafluoroethane on a CFC-conditioned chromia catalyst was investigated. The desired 1,1,1,2-tetrafluoroethane can be obtained from its symmetric isomer in the presence of a chromia catalyst conditioned exclusively with chlorine-free fluorocarbons. In the presence of chlorofluorocarbons, hydrogen chloride is formed as a result of the decomposition reactions of the haloalkane used and is strongly adsorbed on to the surface. This HCl causes a very complex system of side-reactions. In addition, a second kind of chlorine, inactive chloride bonded to chromium, is formed which can only be removed as the result of a very slow solid-gas reaction. Mechanistic information was obtained by examining the effects of substituting DCl for HCl as the chlorine source for the reaction with consecutive isomerization products of 1,1,2,2-tetrafluoroethane. Thus, it is most probable that dehydrohalogenation/hydrohalogenation processes (elimination/addition mechanism) are mainly responsible for the formation of the halo-olefins and halocarbons observed on chromia. As the HCl/DCl adsorbed on the surface is very quickly removed by the reactions with the halocarbons and halo-olefins, it is advantageous to employ pulse techniques to evaluate this reaction system.
- Kemnitz,Niedersen
-
p. 111 - 119
(2007/10/03)
-
- Characterization by Temperature-Programmed Reduction and by Temperature-Programmed Oxidation (TPR-TPO) of Chromium (III) Oxide-Based Catalysts: Correlation with the Catalytic Activity for Hydrofluoroalkane Synthesis
-
The catalytic activity of chromium (III) oxide for the fluorination of CF3CH2Cl (HCFC 133a) is proportional to the number of reversibly oxidized sites.The proportionality coefficient depends on the atmosphere employed during the pretreatment of the catalyst.The temperature-programmed reduction and temperature-programmed oxidation experiments constitute a simple technique that allows the number of reversibly oxidized chromium atoms to be measured.The method of preparation of the chromium hydroxide has little effect on the catalytic properties of chromium (III) oxide.The activation atmosphere and the temperature are essential parameters in the formation of chromium (III) oxide from hydroxide.Indeed, the most active chromium (III) oxide for the fluorination of CF3CH2Cl is obtained by thermal treatment of hydroxide at 380 deg C under nitrogen.
- Brunet, S.,Requieme, B.,Matouba, E.,Barrault, J.,Blanchard, M.
-
-
