- Infrared laser-induced post-pulse dissociation of CF2HCl and CF2Cl2 under high pressure and fluence conditions
-
The unimolecular decomposition of the halogenated methanes CF2HCl (one main channel) and CF2Cl2 (two main channels) in the focused beam of a pulsed CO2 laser under high pressure and fluence conditions (p = 100 Pa-2 kPa; Φ=5-200 J/cm2) was studied by a special laser-induced fluorescence (LIF) technique, permitting spatially resolved fragment concentration measurements in the focal region. Considerable amounts of CF2 product were formed after the end of the laser pulse. In the one-channel-dissociation case of CF2HCl LIF measurements of the CF2 yield distribution Y(z,r) can be related to the spatial distribution of the average absorbed energy in the parent molecules. Only part of the absorbed energy is consumed by multiphoton dissociation, while most reactant molecules remain highly vibrationally excited in the focus volume far into the double cone. Using the long-lived CF2 also as a probe for measuring the rotational, translational, and vibrational temperatures, the redistribution of the internal energy in the molecules and fragments involved is monitored. The post-pulse production of CF2 is shown to be caused by the energy pooling v-v transfer mechanism, while contributions of pyrolytic and gas dynamic processes are of little importance.
- Strube,Wollbrandt,Rossberg,Linke
-
-
Read Online
- Convenient Preparation and Structure Determination of Air- and Moisture-Tolerant Difluoromethylborates
-
Convenient and reliable synthetic methods for difluoromethylborates have been established. The intermediary generated difluoromethylsilicate species from TMSCF2H (TMS=trimethylsilyl) and potassium tert-butoxide were allowed to react with pinBPh (Me4C2O2BPh) in the presence of 18-crown-6 to give the corresponding borate compound [pinB(Ph)CF2H]?K+(18-crown-6) as an air- and moisture-tolerant solid. The unambiguously determined crystal structure of [pinB(Ph)CF2H]?K+(18-crown-6) revealed that the difluoromethylborate unit partially coordinated on the potassium ion. Reaction of [pinB(Ph)CF2H]–K+(18-crown-6) with potassium difluoride (KHF2) in acetic acid enabled substitution of the pinacol unit and phenyl group with fluorides, and gave (difluoromethyl)trifluoroborate [F3BCF2H]–K+(18-crown-6) in a good yield. The crystal structure of air- and moisture-tolerant [F3BCF2H]–K+(18-crown-6), which would be a promising reagent for synthesis of various difluoromethylboron species, showed a polyrotaxane-like polymeric structure based on the K???F interactions between the K+(18-crown-6), CF2H, and BF3 units.
- Yokawa, Akitaka,Ito, Shigekazu
-
-
Read Online
- Capture of the Sulfur Monoxide-Hydroxyl Radical Complex
-
The elusive hydrogen-bonded sulfur monoxide-hydroxyl radical complex (?OH···OS), a missing intermediate in the atmospheric chemistry of SO2, was generated in the 266 nm laser photolysis of the sulfinyl radical HOSO?in cryogenic Ar-matrixes. In addition to the IR spectroscopic characterization with deuteration, its thermal conversion to HOSO?with an activation barrier of 0.33 ± 0.11 kcal mol-1 (calcd 0.32 kcal mol-1, CCSD(T)-F12a/AVTZ) in the temperature range of 15.0-21.0 K and a H/D kinetic isotope effect of 2.4 at 16.0 K have been observed.
- Chen, Changyun,Lu, Bo,Zhao, Xiaofang,Qian, Weiyu,Liu, Jie,Trabelsi, Tarek,Francisco, Joseph S.,Qin, Jie,Li, Jun,Wang, Lina,Zeng, Xiaoqing
-
supporting information
p. 2175 - 2179
(2020/03/03)
-
- Nickel-Catalyzed Difluoromethylation of Arylboronic Acids with Bromodifluoromethane
-
Although bromodifluoromethane (BrCF2H) is a simple and readily available fluorine source, direct formation of difluoromethylated arenes with BrCF2H has not been reported. Herein, we describe an efficient method to access difluoromethylated arenes through a nickel-catalyzed difluoromethylation of arylboronic acids with BrCF2H. The reaction exhibits high efficiency, good functional group tolerance and broad substrate scope, thus providing an efficient route for applications in drug discovery and development. Preliminary mechanistic studies reveal that a difluoromethyl radical is involved in the reaction.
- Fu, Xia-Ping,Xiao, Yu-Lan,Zhang, Xingang
-
supporting information
p. 143 - 146
(2018/01/05)
-
- Metallaphotoredox Difluoromethylation of Aryl Bromides
-
Herein, we report a convenient and broadly applicable strategy for the difluoromethylation of aryl bromides by metallaphotoredox catalysis. Bromodifluoromethane, a simple and commercially available alkyl halide, is harnessed as an effective source of difluoromethyl radical by silyl-radical-mediated halogen abstraction. The merger of this fluoroalkyl electrophile activation pathway with a dual nickel/photoredox catalytic platform enables the difluoromethylation of a diverse array of aryl and heteroaryl bromides under mild conditions. The utility of this procedure is showcased in the late-stage functionalization of several drug analogues.
- Bacauanu, Vlad,Cardinal, Sébastien,Yamauchi, Motoshi,Kondo, Masaru,Fernández, David F.,Remy, Richard,MacMillan, David W. C.
-
p. 12543 - 12548
(2018/09/18)
-
- Selective reduction of a C–Cl bond in halomethanes with Et3GeH at nanoscopic Lewis acidic Aluminium fluoride
-
The selective activation of C–Cl bonds of hydrochlorofluoromethanes and chloromethanes at moderate reaction conditions using ACF in a combination with Et3GeH is presented. The reactions of the chloromethanes (CH3Cl, CH2Cl2, CHCl3 and CCl4) in the presence of Et3GeH and ACF as catalyst led to the activation of only one C–Cl bond resulting in the hydrodechlorination. Friedel-Crafts reactions with benzene as solvent are suppressed by Et3GeH. A selective hydrodechlorination of hydrochlorofluoromethanes was achieved, because a transformation of a C–F bond into a C–H bond by the combination of ACF with Et3GeH did not occur. Supporting PulseTA experiments illustrated the interaction between the solid catalyst and Et3GeH, the solvent benzene or CH2Cl2.
- Mei?ner, Gisa,Feist, Michael,Braun, Thomas,Kemnitz, Erhard
-
p. 234 - 241
(2017/09/12)
-
- A tetrafluoroethylene in the product from the separation method of difluoromethane
-
The invention relates to a method for separation of difluoromethane from a tetrafluoroethylene product. The method is characterized by including the steps of: 1) extraction: introducing a difluoromethane containing tetrafluoroethylene product into an extraction tower, conducting extraction with an extraction agent, then recovering tetrafluoroethylene, and letting tetrafluoroethylene enter a stripping tower along with the extraction agent; 2) stripping: heating the stripping tower bottom, stripping difluoromethane out of the extraction agent, and recovering difluoromethane into a low pressure storage tank; and 3) membrane separation: subjecting the difluoromethane gas in the low pressure storage tank to membrane separation so as to obtain high purity difluoromethane gas. The separation method provided by the invention can realize the effective separation of tetrafluoroethylene and difluoromethane, on the one hand can reduce material waste, and on the other hand can reduce environmental pollution, thus having good social benefits.
- -
-
Paragraph 0020-0037
(2017/09/02)
-
- Bis(difluoromethyl)trimethylsilicate Anion: A Key Intermediate in Nucleophilic Difluoromethylation of Enolizable Ketones with Me3SiCF2H
-
A pentacoordinate bis(difluoromethyl)silicate anion, [Me3Si(CF2H)2]?, is observed for the first time by the activation of Me3SiCF2H with a nucleophilic alkali-metal salt and 18-crown-6. Further study on its reactivity by tuning the countercation effect led to the discovery and development of an efficient, catalytic nucleophilic difluoromethylation of enolizable ketones with Me3SiCF2H by using a combination of CsF and 18-crown-6 as the initiation system. Mechanistic investigations demonstrate that [(18-crown-6)Cs]+[Me3Si(CF2H)2]?is a key intermediate in this catalytic reaction.
- Chen, Dingben,Ni, Chuanfa,Zhao, Yanchuan,Cai, Xian,Li, Xinjin,Xiao, Pan,Hu, Jinbo
-
supporting information
p. 12632 - 12636
(2016/10/31)
-
- METHOD FOR PRODUCING DIFLUOROMETHANE
-
A method for producing difluoromethane, including the catalytic reaction of dichloromethane with hydrogen fluoride in the liquid phase, in the presence of chlorine, and in the presence of an ionic liquid catalyst consisting of the product of the reaction of antimony pentachloride with an organic salt having the general formula X+A, where A is a halide anion or hexafluoroantimonate, and X+ is a quaternary ammonium cation, quarternary phosphonium or ternary sulfonium. Further, equipment suitable for implementing said method.
- -
-
Paragraph 0121-0125
(2015/08/04)
-
- Xenon(IV)-carbon bond of [C6F5XeF2]+; Structural characterization and bonding of [C6F5XeF2][BF4], [C6F5XeF2][BF4]·2HF, and [C6F5XeF2][BF4]· n NCCH 3 (n = 1, 2); And the fluorinating properties of [C6F5XeF2][BF4]
-
The [C6F5XeF2]+ cation is the only example of a XeIV-C bond, which had only been previously characterized as its [BF4]- salt in solution by multi-NMR spectroscopy. The [BF4]- salt and its new CH3CN and HF solvates, [C6F5XeF2][BF4]·1.5CH3CN and [C6F5XeF2][BF4]·2HF, have now been synthesized and fully characterized in the solid state by lowerature, single-crystal X-ray diffraction and Raman spectroscopy. Crystalline [C6F5XeF2][BF4] and [C6F5XeF2][BF4]·1.5CH3CN were obtained from CH3CN/CH2Cl2 solvent mixtures, and [C6F5XeF2][BF4]·2HF was obtained from anhydrous HF (aHF), where [C6F5XeF2][BF4]·1.5CH3CN is comprised of an equimolar mixture of [C6F5XeF2][BF4]·CH3CN and [C6F5XeF2][BF4]·2CH3CN. The crystal structures show that the [C6F5XeF2]+ cation has two short contacts with the F atoms of [BF4]- or with the F or N atoms of the solvent molecules, HF and CH3CN. The lowerature solid-state Raman spectra of [C6F5XeF2][BF4] and C6F5IF2 were assigned with the aid of quantum-chemical calculations. The bonding in [C6F5XeF2]+, C6F5IF2, [C6F5XeF2][BF4], [C6F5XeF2][BF4]·CH3CN, [C6F5XeF2][BF4]·2CH3CN, and [C6F5XeF2][BF4]·2HF was assessed with the aid of natural bond orbital analyses and molecular orbital calculations. The 129Xe, 19F, and 11B NMR spectra of [C6F5XeF2][BF4] in aHF are reported and compared with the 19F NMR spectrum of C6F5IF2, and all previously unreported J(129Xe-19F) and J(19F-19F) couplings were determined. The long-term solution stabilities of [C6F5XeF2][BF4] were investigated by 19F NMR spectroscopy and the oxidative fluorinating properties of [C6F5XeF2][BF4] were demonstrated by studies of its reactivity with K[C6F5BF3], Pn(C6F5)3 (Pn = P, As, or Bi), and C6F5X (X = Br or I).
- Koppe, Karsten,Haner, Jamie,Mercier, Hlne P. A.,Frohn, Hermann-J.,Schrobilgen, Gary J.
-
p. 11640 - 11661
(2015/01/16)
-
- Rhodium-carbon bond energies in Tp′Rh(CNneopentyl)(CH2X)H: Quantifying stabilization effects in M-C bonds
-
A series of substituted methyl derivatives of the type Tp′ Rh(CNneopentyl)(CH2X)H (CH2X = CH2C(i - O)CH3, CH2Ci - CCH3, CH 2O-t-Bu, CH2CF3, CH2F, CHF 2) was synthesized either by photolysis of Tp′Rh(CNneopentyl) (PhNCNneopentyl) in neat CH3X or by exchange with the labile hydrocarbon in Tp′Rh(CNneopentyl)(n-pentyl)H or Tp′Rh(CNneopentyl) (CH3)H. Only a single product was observed in each case. Clean reductive elimination was observed for all compounds in C6D 6. Structures of these complexes and their corresponding chlorinated derivatives have been characterized by NMR spectroscopy, elemental analysis, and X-ray crystallography. Relative Rh-C bond energies are calculated using previously established kinetic techniques, and two separate linear correlations are observed versus known C-H bond strengths, one for the parent hydrocarbons, and one for the substituted hydrocarbons. Both correlations have slopes of 1.4, and are separated vertically by 7.5 kcal mol-1 (-CH2X above -CxHy). In addition, it is now clear that preferences for linear vs branched olefin insertion products in substituted derivatives can be predicted on the basis of the strengths of the β-C-H bonds. The DFT calculations of the metal-carbon bond strengths in these Rh-CH2X derivatives with α-substitution show a trend that is in good agreement with the experimental results.
- Jiao, Yunzhe,Evans, Meagan E.,Morris, James,Brennessel, William W.,Jones, William D.
-
p. 6994 - 7004
(2013/06/27)
-
- The use of active carbon pretreated at 2173 K as a support for palladium catalysts for hydrodechlorination reactions
-
A commercial active carbon was heat-treated at 2173 K in argon and then subjected to steam gasification, yielding a series of very pure, turbostratic carbon materials, characterized by different specific surface areas and pore volume. These materials served as supports for palladium catalysts. Their pore structure, apparent absence of oxygen containing functional groups and hydrophobic character have a great effect on the dispersion of palladium introduced by impregnation. The use of an acetone solution of palladium acetate rather than an aqueous solution of palladium chloride (a typical Pd precursor) for the impregnation gives better results for preparing more metal dispersed Pd/C catalysts, especially for carbons with smaller micropore volumes. All preheated carbon-supported palladium catalysts showed very good activity and selectivity to CH2F2 in CCl2F2 (CFC-12) hydrodechlorination, up to 90% at the highest reaction temperature. In contrast, untreated or only HCl-washed carbons showed inferior catalytic properties. Residual phosphorus in the active carbons which were present in the active carbons which have not been subjected to thermal treatment, appears to be responsible for deterioration of catalytic properties of Pd/C. After reaction the presence of interstitial carbon (originating from the CFC-12 molecule) in the Pd lattice was found in the catalysts characterized by lower and medium metal dispersions.
- Bonarowska, Magdalena,Raróg-Pilecka, Wioletta,Karpiński, Zbigniew
-
body text
p. 223 - 231
(2012/02/03)
-
- Experimental and chemical kinetic study of the pyrolysis of trifluoroethane and the reaction of trifluoromethane with methane
-
A detailed reaction mechanism is developed and used to model experimental data on the pyrolysis of CHF3 and the non-oxidative gas-phase reaction of CHF3 with CH4 in an alumina tube reactor at temperatures between 873 and 1173 K and at atmospheric pressure. It was found that CHF3 can be converted into C2F4 during pyrolysis and CH2=CF2 via reaction with CH4. Other products generated include C3F6, CH 2F2, C2H3F, C2HF 3, C2H6, C2H2 and CHF2CHF2. The rate of CHF3 decomposition can be expressed as 5.2×1013[s-1]e -295[kJmol-1]/RT. During the pyrolysis of CHF3 and in the reaction of CHF3 with CH4, the initial steps in the reaction involve the decomposition of CHF3 and subsequent formation of CF2 difluorocarbene radical and HF. It is proposed that CH4 is activated by a series of chain reactions, initiated by H radicals. The NIST HFC and GRI-Mech mechanisms, with minor modifications, are able to obtain satisfactory agreement between modelling results and experimental data. With these modelling analyses, the reactions leading to the formation of major and minor products are fully elucidated.
- Han, Wenfeng,Kennedy, Eric M.,Kundu, Sazal K.,MacKie, John C.,Adesina, Adesoji A.,Dlugogorski, Bogdan Z.
-
scheme or table
p. 751 - 760
(2010/09/04)
-
- 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)
-
- Electrophilic (phenylsulfonyl)difluoromethylation of thiols with a hypervalent iodine(III)-CF2SO2Ph reagent
-
A hypervalent iodine(III)-CF2SO2Ph compound (3) has been successfully prepared with selective nucleophilic reaction using PhSO2CF2SiMe3 reagent, and this previously unkown compound 3 was found to act as a new electrophilic (phenylsulfonyl)difluoromethylation reagent for a variety of S-nucleophiles under very mild reaction conditions.
- Zhang, Wei,Zhu, Jieming,Hu, Jinbo
-
p. 5006 - 5008
(2008/12/21)
-
- PRODUCTION PROCESSES FOR MAKING 1,1,1,2,2,3-HEXAFLUOROPROPANE
-
A process for making HFC-236cb is disclosed. The process comprises reacting TFE with HFC-32 in the presence of at least one co-product and a suitable catalyst to produce a product mixture comprising HFC-236cb, wherein the total amount of the at least one co-product is at least 10 ppmv based on the total amount of the tetrafluoroethylene, the difluoromethane and the at least one co-product.
- -
-
Page/Page column 14
(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 6-7
(2008/06/13)
-
- Porous aluminum fluoride
-
A porous aluminum fluoride on which SbClxF5-x (wherein x represents a numeral of 0 to 5) is supported, SbClxF5-x being obtainable by supporting SbCl, or the like on a porous aluminum fluoride and treating it with hydrogen fluoride. The resulting porous aluminum fluoride has a high activity as a fluorinating agent, a fluorination catalyst, or the like, is easy to handle, can be used for a flow-type reaction, and also can be used even at a high temperature.
- -
-
Page/Page column 4
(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)
-
- Noncatalytic manufacture of 1,1,3,3,3-pentafluoropropene from 1,1,1,3,3,3-hexafluoropropane
-
1,1,3,3,3-Pentafluoropropene (CF3CH═CF2, HFC-1225zc) can be produced by pyrolyzing 1,1,1,3,3,3-hexafluoropropane (CF3CH2CF3, HFC-236fa) in the absence of dehydrofluorination catalyst at temperatures of from about 700° C. to about 1000° C. and total pressures of about atmosphere pressure in an empty, tubular reactor, the interior surfaces of which comprise materials of construction resistant to hydrogen fluoride.
- -
-
Page/Page column 4
(2008/06/13)
-
- Method of making difluoromethane, 1,1,1-trifluoroethane and 1,1-difluoroethane
-
A process for the production of difluoromethane (HFC-32), 1,1,1-trifluoroethane (HFC-143a) and 1,1-difluoroethane (HFC-152a). In the process the following steps are employed: (a) providing a reaction vessel, (b) providing in the reaction vessel activated carbon impregnated with a strong Lewis acid fluorination catalys selected from halides of As, Sb, Al, TI, In, V, Nb, Ta, Ti, Zr and Hf, (c) activating the catalyst by passing through the activated carbon impregnated with a strong Lewis acid fluorination catalyst anhydrous hydrogen fluoride gas and chlorine gas, (d) contacting, in a vapor state in the reaction vessel containing the activated catalyst, hydrogen fluoride and one or more halogenated hydrocarbons selected from chlorofluoromethane, dichloromethane, 1,1,1-trichloroethane, vinyl chloride, 1,1-dichloroethylene, 1.2-dichloroethylene, 1,2-dichloroethane, and 1,1-dichloroethane for a time and at a temperature to produce a product stream comprising hydrofluorocarbon product(s) corresponding to the chlorinated hydrocarbon reactant(s), and one or more of hydrogen chloride, unreactacted chlorinated hydrocarbon reactant(s), under-fluorinated intermediates, and unreacted hydrogen fluoride, and (e) separating the hydrofluorocarbon product(s) from the product stream.
- -
-
Page/Page column 3
(2010/02/14)
-
- METHOD OF PRODUCING HYDROFLUOROCARBONS
-
A process for producing fluorinated C1 HFCs comprising fluorinating a reactive organic compound, such as dichloromethane, to produce a reaction product comprising at least the desired C1 HFC, such as difluoromethane (HFC-32), unreacted reactive organic compound and a byproduct, such as chloromethane (HCC-40), having a boiling point between the boiling point of said desired hydrofluorocarbon compound and said reactive organic compound; and removing from the reaction product at least a substantial portion of the byproduct to produce a high purity product stream.
- -
-
Page/Page column 20-21
(2008/06/13)
-
- PRODUCT STREAM PROCESSING METHODS, PRODUCT STREAM PROCESSING SYSTEMS, AND MIXTURES
-
Product stream processing methods, systems, and mixtures are provided. A reaction product stream can have a first amount of a halogen exchange by product and an azeotropic composition of a halogen exchange reaction product and a halogen donating reactant. A majority of the halogen exchange by-product from the reaction product stream can be removed to produce a mixture. The mixture can include the halogen exchange reaction product, the halogen donating reactant, and a second amount of the halogen exchange by-product that is less than the first amount of the halogen donating reactant. A majority of the halogen exchange reaction product containing less than the azeotropic amount of the halogen donating reactant can be removed from the mixture. Exemplary halogen exchange reaction product, halogen donating reactant and halogen exchange by-product are CH2F2, HF, and HCI respectively.
- -
-
Page/Page column 8
(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 11; 16
(2008/06/13)
-
- A PROCESS FOR THE PRODUCTION OF DIFLUOROMETHANE
-
A process for vapor phase fluorination of methylene chloride with anhydrous hydrogen fluoride (AHF) in the presence of a coprecipitated chromia-alumina impregnated with zinc salt as catalyst, removing (HCl) and heavier components by distillation, subjecting (HFC-32) rich cut to a further step of fluorination catalyst.
- -
-
-
- Process for the production of difluoromethane
-
A process for vapor phase fluorination of methylene chloride with anhydrous hydrogen fluoride (AHF) in the presence of a coprecipitated chromia-alumina impregnated with zinc salt as catalyst, removing HCl and heavier components by distillation, subjecting HFC-32 rich cut to a further step of fluorination in the presence of a fluorination catalyst.
- -
-
-
- Method of making hydrofluorocarbons
-
A manufacturing process for making hydrofluorocarbons (HFCs), by reacting a hydrochlorocarbon and HF in a liquid phase catalytic reactor using a large mole ratio of HF to hydrochlorocarbon to minimize formation of high boiling by-products and improve HF consumption and hydrofluorocarbon yields.
- -
-
-
- METHOD OF PRODUCING DIFLUOROMETHANE
-
Disclosed is a method of producing difluoromethane (HFC-32), which comprises firstly reacting methylene chloride with hydrogen fluoride in gas phase at 280 to 340° C. in the presence of a fluorinated catalyst to produce chlorofluoro methane, and secondly reacting the chlorofluoro methane with hydrogen fluoride in liquid phase at 60 to 80° C. in the presence of an antimony chloride catalyst. The method is advantageous in that HFC-32 is produced in high yield under mild reaction conditions using a relatively small amount of energy.
- -
-
-
- Process for the manufacture of defluoromethane
-
The subject of the invention is a continuous process for the manufacture of difluoromethane (F32) from methylene chloride (F30) and hydrogen fluoride in the presence of chlorine, in the gas phase, over a fluorination catalyst. According to the invention, the gas flow exiting from the reactor is subjected to a distillation in order to separate, at the top, a flow containing virtually all the HCl and at least 90% of the F32 produced by the reaction and, at the bottom, a flow containing at least 90% of the unconverted reactants (F31, F30 and HF) and the latter flow is recycled directly to the reactor, without any purification operation.
- -
-
Page/Page column 5-6
(2008/06/13)
-
- Hydrodechlorination of dichlorodifluoromethane over novel CrF3 supported palladium catalysts
-
Novel CrF3 supported palladium catalysts have been prepared through two different precursors i.e. dichlorobistriphenyl-phosphine palladium (DCTPPP) and PdCl2 for the hydrodechlorination of CFC-12. These catalysts exhibited improved catalytic activities in hydrodechlorination of CFC-12 as compared with conventional Pd/γ-Al2O3-. Particularly, high selectivities (~81%) of CH2F2 formation have been achieved over DCTPPP/CrF3. The improved catalytic performance may be attributed to the nature of support CrF3 and the formation of fine palladium particles in the catalysts.
- Cao, Yu Cai,Jiang, Xuan Zhen
-
p. 1607 - 1611
(2007/10/03)
-
- Hydrodechlorination of dichlorodifluoromethane (CFC-12) on silica-supported palladium and palladium-gold catalysts
-
Silica-supported palladium and palladium-gold catalysts were screened in the reaction of dichlorodifluoromethane with dihydrogen at 180°C. The Au-containing sample appeared superior as far as the selectivity towards difluoromethane (desired reaction product) is concerned (95% vs. ~30% for Pd/SiO2). A comparative X-ray diffraction study of the catalysts, before and after reaction, confirmed our earlier findings that during the hydrodechlorination massive amounts of carbon originated from CCl2F2 dissolve in palladium. However, a similar conclusion cannot be drawn from XRD studies of the Pd-Au/SiO2 catalyst, because upon entering Pd bulk both gold and carbon may produce analogous shifts of the XRD reflections. For that reason, temperature programmed hydrogenation of carbon deposited in the Pd and a Pd-Au catalyst was used. In contrast to the behaviour of monometallic Pd/SiO2, only insignificant quantity of carbon was found in the bimetallic Pd-Au/SiO2 sample subjected to hydrodechlorination. This result supports the idea that a complete hydrodehalogenation of CCl2F2 to methane would occur via bare carbon adspecies. Thus, one can associate a superior catalytic behaviour of Pd-Au alloy catalysts (selectivity to CH2F2 ~95%) with a low abundance of C1 adspecies.
- Malinowski
-
p. 1461 - 1466
(2007/10/03)
-
- Process for the production of difluoromethane
-
The present invention provides a vapor phase process for the production of difluoromethane, HFC-32. The process of this invention provides for the preparation of HFC-32 by a process that exhibits both good product yield and selectivity.
- -
-
Page column 4
(2008/06/13)
-
- Process for producing difluoromethane
-
A process is disclosed for producing difluoromethane by fluorinating dichloromethane with hydrogen fluoride in a liquid phase in the presence of a catalyst, wherein the reaction is conducted at a temperature within the range from 80 to 150° C. under a pressure within the range from 8 to 80 kg/cm2using a mixture of antimony pentafluoride and antimony trifluoride, or antimony pentafluoride as the fluorinating catalyst. The process economically and safely produces difluoromethane from dichloromethane and hydrogen fluoride.
- -
-
Page column 4
(2008/06/13)
-
- Production of fluorinated ethanes using elemental fluorine
-
Scientific principles of industrial gas-phase fluorination of fluoroethanes with elemental fluorine were developed. Conditions for fluorination of low-fluorinated ethanes without rupture of the C-C bond were determined.
- Pashkevich,Mukhortov,Alekseev,Asovich
-
p. 1269 - 1274
(2007/10/03)
-
- Fluorinated phosphonium ylides: Versatile in situ Wittig intermediates in the synthesis of hydrofluorocarbons
-
A simple and convenient technique has been developed for the synthesis, characterisation and isolation of hydrofluoro/hydrohalofluorocarbons such as chlorodifluoromethane (CF2ClH), difluoromethane (CF2H2), bromodifluoromethane (CF2BrH) and dibromofluoromethane (CFBr2H) as possible chlorofluorocarbon (CFC) alternatives. The Wittig reaction of carbonyl compounds with in situ generated triphenylphosphonium ylides in DMF forms terminal fluoroolefins. However, in the absence of the carbonyl moiety these ylides undergo decomposition. The high reactivity of fluoromethylene triphenylphosphonium ylides in DMF in the absence of the carbonyl moiety has been exploited for the first time to design the synthesis of hydrofluorocarbons.
- Bhadury, Pinaki S.,Palit, Meehir,Sharma, Mamta,Raza, Syed K.,Jaiswal, Devendra K.
-
-
- Characterization and reactivity of Pd/MgO and Pd/?3-Al2O3 catalysts in the selective hydrogenolysis of CCl2F2
-
Al2O3 and MgO supported Pd catalysts with 6 wt % loading are prepared by the wet impregnation method. The catalysts are made into two parts; one of them is dried at 110 ?°C, and the other one is calcined at 500 ?°C. Conversion of CCl
- Aytam, Hari Padmasri,Akula, Venugopal,Janmanchi, Krishnamurthy,Rao Kamaraju, Seetha Rama,Rao Panja, Kanta,Gurram, Kishan,Niemantsverdriet
-
p. 1024 - 1031
(2007/10/03)
-
- 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)
-
- 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)
-
- An experimental and modelling study of ignition delays in shock-heated ethane-oxygen-argon mixtures inhibited by 2H-heptafluoropropane
-
Ignition delay times have been measured behind reflected shock waves in ethane-oxygenargon mixtures at temperatures between 1150 and 1500 K and pre-ignition pressures between 10 and 14 atm. Delay times have been measured both by pressure rise and OH absorption at 307 nm. Kinetic modelling of the ignition delays has been made using the GRIMech 3.0 mechanism which with addition of several reactions involving HO2 radicals and an increase in the barrier for reaction between C2H5 and O2 can satisfactorily model delays over the studied equivalence ratios of φ= 1.7 to 0.68. Addition of 2H-heptafluoropropane up to 13 mol % (of ethane) had little inhibition effect on stoichiometric ethane-oxygen-argon mixtures but inhibited ignition in a mixture of φ= 1.5. A kinetic mechanism is presented to model the inhibition process. by Oldenbourg Wissenschaftsverlag, Muenchen.
- Ikeda, Emi,Mackie, John C.
-
p. 997 - 1009
(2007/10/03)
-
- Experimental and computational studies on the gas-phase reaction of CBrF3 with hydrogen
-
Gas-phase hydrogen dehalogenation of halon 1301 (bromotrifluoromethane, CBrF3) has been studied experimentally in a tubular alumina reactor operating at atmospheric pressure. It is found that hydrogen can accelerate the decomposition of halon 1301 and that conversion levels of CBrF3 and H2 increase with temperature and residence time. CBrF3 conversion increases with decreasing input volume ratio of CBrF3 to H2. The species produced are a complex mixture of halogenated hydrocarbons including CHF3, CH2F2, C2HF3, C2F6, C2H2F4, C2HF5, CHBrF2, CH3Br, CH2Br2, CHBr2F, and CH2BrF in addition to HBr and HF. The production yield of CHF3, the major product, increases with temperature to 1023 K, after which CHF3 levels decrease with increasing temperature. Conversely, CHF3 selectivity decreases with increasing temperature, residence time, or input ratio of CBrF3 to H2. The initiation reaction is believed to be the rupture of the C-Br bond in CBrF3, and the radical species CF3 then reacts with H2 to produce H and CHF3. The key step in the process is the attack of H radical on CBrF3 to produce CF3 and HBr. Experimental data are compared with the model predictions, and good agreement between experimental and modeling prediction is obtained for CHF3 production. However, the existing mechanism does not predict the formation of CHBrF2, which is detected during the experimental study, and the concentrations of CH2F2 and C2F6 measured experimentally are significantly different from those predicted. Modifications to the existing NIST mechanism are suggested to improve the prediction of the quantity of these species produced. Gas-phase hydrogen dehalogenation of halon 1301 (bromotrifluoromethane, CBrF3) has been studied experimentally in a tubular alumina reactor operating at atmospheric pressure. It is found that hydrogen can accelerate the decomposition of halon 1301 and that conversion levels of CBrF3 and H2 increase with temperature and residence time. CBrF3 conversion increases with decreasing input volume ratio of CBrF3 to H2. The species produced are a complex mixture of halogenated hydrocarbons including CHF3, CH2F2, C2HF3, C2F6, C2H2F4, C2HF5, CHBrF2, CH3Br, CH2Br2, CHBr2F, and CH2BrF in addition to HBr and HF. The production yield of CHF3, the major product, increases with temperature to 1023 K, after which CHF3 levels decrease with increasing temperature. Conversely, CHF3 selectivity decreases with increasing temperature, residence time, or input ratio of CBrF3 to H2. The initiation reaction is believed to be the rupture of the C-Br bond in CBrF3, and the radical species CF3 then reacts with H2 to produce H and CHF3. The key step in the process is the attack of H radical on CBrF3 to produce CF3 and HBr. Experimental data are compared with the model predictions, and good agreement between experimental and modeling prediction is obtained for CHF3 production. However, the existing mechanism does not predict the formation of CHBrF2, which is detected during the experimental study, and the concentrations of CH2F2 and C2F6 measured experimentally are significantly different from those predicted. Modifications to the existing NIST mechanism are suggested to improve the prediction of the quantity of these species produced.
- Li, Kai,Kennedy, Eric M.,Moghtaderi, Behdad,Dlugogorski, Bogdan Z.
-
p. 584 - 590
(2007/10/03)
-
- Hydrodechlorination of dichlorodifluoromethane over palladium model catalysts and a comparison with the hydrodechlorination of 1,1-dichlorotetrafluoroethane
-
The hydrodechlorination of dichlorodifluoromethane (CFC-12) was performed on small surface area model catalysts, including Pd(111) and Pd(110) single crystals and polycrystalline Pd foil, in a batch reactor at 1 atm and 423-523 K. The main products were CH2F2 and methane. Ethane could be detected at higher temperatures, e.g., 513 K, with selectivity 2F2 was two orders of magnitude lower, the mono-dechlorinated product (CHClF2) was not produced, and the bulk palladium hydrogen activity was not detected. Pd foil was more active than the single crystals, probably due to a higher activity from the steps and kinks. Pd(111) showed a lower deactivation rate, lower selectivity toward CH2F2, and higher activation energy for CH2F2 formation than the other catalysts, indicating a weaker Pd-Cl interaction on this surface, resulting in greater difficulty in breaking the C-Cl bond.
- Somorjai,Ramos,Ramos,Schmal,Aranda
-
p. 423 - 431
(2007/10/03)
-
- Magnesium fluoride as a catalytic support in hydrodechlorination of CCl2F2 (CFC-12)
-
Magnesium fluoride-supported palladium and ruthenium appear to be useful catalysts in the reaction of CCl2F2 (CFC-12) hydrodechlorination; after doping Pd/MgF2 with gold the selectivity for CH2F2 increased from ~ 70 to almost 90%.
- Malinowski,Juszczyk,Pielaszek,Bonarowska,Wojciechowska,Karpinski
-
p. 685 - 686
(2007/10/03)
-
- Generation of 'naked' fluoride ions in unprecedentedly high concentrations from a fluoropalladium complex
-
An F-/Cl- ligand exchange in the stable organopalladium fluoro complex 1 generates naked fluoride ions in unusually high concentrations. The released Freadily fluorinates dichloromethane under exceedingly mild conditions and deprotonates chloroform to produce dichlorocarbene.
- Grushin, Vladimir V.
-
p. 994 - 996
(2007/10/03)
-
- Electrochemical reduction of CCl2F2 on Nafion solid polymer electrolyte composite electrodes
-
The electrochemical reduction of CCl2F2 (CFC-12) was carried out at Pd, Au, Cu and Ag cathodes, which were chemically deposited on Nafion 117 (H+ form) membrane; the main electrolysis product at -1.0 V vs. Ag/AgCl at Au, Pd and Cu was CH4) with current efficiencies (CE) of 14, 15 and 47% respectively, while at Ag cathode, in addition to CH4, a considerable quantity of CH2F2 (CE 60%) was also detected, which might be used as a new technology refrigerant.
- Delli,Kouloumtzoglou,Kyriacou,Lambrou
-
p. 1693 - 1694
(2007/10/03)
-
- Preparation of and fluoroalkylation with (chlorodifluoromethyl)trimethylsilane, difluorobis(trimethylsilyl)methane, and 1,1,2,2-tetrafluoro-1,2-bis(trimethylsilyl)ethane
-
CF2BrCl reacts with aluminum/N-methylpyrrolidinone in the presence of chlorotrimethylsilane to give Me3SiCF2Cl in high yield. Similarly, CF2Br2 gives Me3SiCF2Br with bromotrimethylsilane. Chlorodifluoromethylation of aldehydes using Me3SiCF2Cl and a catalytic amount of TBAF in polar solvents occurs at room temperature, providing difluoromethylated alcohols in two steps. Electroreduction of Me3SiCF2Cl in the presence of chlorotrimethylsilane gives Me3SiCF2SiMe3 (anion-derived product) and Me3SiCF2CF2SiMe3 (radical-derived product). Using THF/HMPA strongly favors the former, whereas THF/TDA-1 (tris(3,6-dioxaheptyl)amine) the latter. Me3SiCF2SiMe3 difluoromethylates aldehydes acting as a difluoromethylene dianion ('CF22-'/equivalent), whereas Me3SiCF2CF2SiMe3 acts at room temperature as an in situ source for the perfluorovinyl anion (due to β-elimination of fluorotrimethylsilane). However, at low temperature the elimination pathway is suppressed and tetrafluoroethylene dianion ('-CF2CF2-'/equivalent) behavior is observed. The structure of Me3SiCF2CF2SiMe3 was analyzed by X-ray diffraction. All of the studied fluoroalkylating reagents are moisture- and air-stable and can be readily obtained from a single convenient precursor (CF2BrCl).
- Yudin, Andrei K.,Prakash, G. K. Surya,Deffieux, Denis,Bradley, Michael,Bau, Robert,Olah, George A.
-
p. 1572 - 1581
(2007/10/03)
-
- Mechanistic study of the selective hydrogenolysis of CCl2F2 (CFC-12) into CH2F2 (HFC-32) over palladium on activated carbon
-
The influence of process parameters such as temperature (400-560K), H2/CCl2F2 ratio (2.2-20), and Weight Hourly Space Velocity (WHSV) (0.3-1.0 g/(g·h)) on the hydrogenolysis of CCl2F2 into CH2F2 over palladium on activated carbon has been investigated. The reactivity of CHClF2 and CH2F2 and the influence of HCl were also examined. In the reaction of CCl2F2, the main product is CH2F2. Significant amounts of CHClF2 and CH4 are also found. The catalyst shows a remarkably high selectivity to CH2F2, in the range of 70-90 mol%, at all conversion levels in a broad range of process conditions. A mechanism is proposed in which the reaction proceeds mainly via parallel reaction pathways. One route results in CH2F2 and CHClF2, while the other route yields CH4. The selectivity to CH2F2 and CHClF2 is determined by the amount of adsorbed chlorine on the catalytic surface and a constant selectivity for CH4 was found. High selectivity for CH2F2 can be achieved at high H2/CCl2F2 ratios and low HCl concentration. The postulated mechanism is supported by thermodynamic data.
- Van De Sandt, Emile J.A.X.,Wiersma, Andre,Makkee, Michiel,Van Bekkum, Herman,Moulijn, Jacob A.
-
p. 505 - 510
(2007/10/03)
-
- Selective fluorination of dichloromethane by highest oxidation state transition-metal oxide fluorides
-
In contrast to the reactivity of high oxidation state binary transition-metal fluorides with organic solvents, many transition-metal oxide fluorides do not react with CH2Cl2. Only the highest oxidation state species react, at temperatures below room temperature, via Cl-F exchange with > 90% selectivity, affording unstable high oxidation state chloro complexes which decompose to chlorine and lower oxidation state species.
- Holloway, John H.,Hope, Eric G.,Townson, Paul J.,Powell, Richard L.
-
p. 105 - 107
(2007/10/03)
-
- Adsorption and Reaction of Trifluoromethyl Iodide on Ni(111)
-
We have investigated the surface chemistry of trifluoromethyl iodide adsorbed on Ni(111) under ultrahigh-vacuum conditions using temperature-programmed desorption, reflection absorption infrared spectroscopy, and Auger electron spectroscopy.Ni(111) activates both carbon-iodine and carbon-fluorine bonds in adsorbed CF3I.Atomic iodine desorbs from the surface near 975 K, and nickel fluoride, NiF2, desorbs near 820 K.Although the desorption temperatures for iodine and nickel fluoride are high, there is evidence that carbon-iodine and carbon-fluorine bonds are actived below room temperature.A small amount of fluorocarbon products containing CF2 and CF3 fragments desorb from the surface between 200 and 375 K.At higher temperatures, fluorine atoms recombine with adsorbed carbon to form CF4, which desorbs near 780 K.CF3I molecularly desorbs from the surface at high coverages with desorption rate maxima of 162 and 122 K for the monolayer and multilayer, respectively.Coadsorption of D atoms and CF3I results in the desorption of CD2F2 near 230 K and DF between 260 and 460 K.After desorption of the monolayer, the bands in the infrared spectrum are quite weak.The IR data suggest that very few fluorocarbon fragments are stabilized on the surface.In general, the data indicate that a large fraction of adsorbed CF3I decomposes to form atomic carbon, fluorine and iodine.A comparison of the reactions of CF3I on Ni to Ag, Pt and Ru shows that only Ni is etched under ultrahigh-vacuum conditions by CF3I.
- Myli K. B.,Grassian, V. H.
-
p. 5581 - 5587
(2007/10/02)
-
- Effect of the Metal-Support Interaction on the Catalytic Properties of Palladium for the Conversion of Difluorodichloromethane with Hydrogen: Comparison of Oxides and Fluorides as Supports
-
The reaction of difluorodichloromethane with hydrogen has been studied between 433 and 523 K and atmospheric pressure, over Pd catalysts supported on graphite and oxides or fluorides of Al, Ti, and Zr.In CF2Cl2 hydrogenation, CH2F2 and CH4 represented more than 95percent of the products.The catalytic properties of fluoride supported catalysts did not undergo any change as a function of time.In contrast, Pd supported on oxides showed changes in selectivity during the first hours on stream.This was ascribed to the reaction of the oxide support with HF released during the reaction.Alumina and titania were nearly completely converted to the corresponding fluorides, but not zirconia.The selectivity to the desired product CH2F2 was 56percent for Pd/graphite and reached 90percent for Pd/ZrF4.The kinetic study suggested that the selectivity was controlled by the bond strength between a carbene-like species CF2 and the surface.The strength of this interaction is supposed to vary with electron availability at the Pd surface, and this hypothesis was then investigated by infrared spectroscopy using the adsorption of CO on Pd/Al2O3 and Pd/AlF3.The results show that the morphology of the Pd particles was little affected by the support and that AlF3-supported Pd becomes electron deficient, due to the strong Lewis acidity of the support.This effect is mainly a short-range effect which is better induced by supports made up of a mixture of fluorides, oxyfluorides, and hydroxyfluorides, rather than pure fluorides.Catalytic properties similar to those of Pd/AlF3 and ZrF4 can be simulated with Pd/graphite samples promoted with small amounts of aluminum or zirconium.
- Coq, Bernard,Figueras, Francois,Hub, Serge,Tournigant, Didier
-
p. 11159 - 11166
(2007/10/02)
-
- Photolysis of Fluorine Molecules Trapped in Solid Methane at 15 K: Evidence of the Reaction of Vibrationally Excited CH3F Molecules with F2
-
The kinetics of reactions initiated via F2 photolysis in solid methane at 15 K was studied with IR spectroscopy.CH3F...HF complexes, formed in a cage reaction with a quantum yield of 0.55 +/- 0.10, are the main products of the photolysis at a host:guest matrix ratio MIR > 5.At MIR 100 the formation of CH2F2 is also detected.Its quantum yield grows linearly with F2 concentration in the MIR range 100-13.The formation of CH2F2 is suggested to be due to the reaction of the F2 molecule with a highly vibrationally excited primary product CH3F*, formed upon photolysis of the reactant clusters (F2*CH4*F2).
- Misochko, E. Ya.,Benderskii, V. A.,Goldschleger, A. U.
-
p. 13917 - 13920
(2007/10/02)
-