- 2-Chloro-2,2-difluoracetamide (ClF2CC(O)NH2). Thermal decomposition, vapour infrared, mass spectrometry, low-temperature NMR, and theoretical studies. Solvent effects on conformational preferences
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Gas-phase thermal decomposition of 2-chloro-2,2-difluoracetamide (CDFA) was studied at temperatures between 270 and 290°C. The rate constant for the decomposition follows the Arrhenius equation. k = (5.5 ± 0.3) · 1016s-1 exp [-(104±4)kj mol-1/RT] Mass spectrometry was used to analyze the decomposition pattern of the title compound. The FT-IR spectrum of the vapour phase and the infrared spectra of CDFA in protic and aprotic solvents were recorded. Potential energy surfaces were studied by theoretical calculations performed at the density functional theory level (PBEPBE and B3LYP methods) using the 6-31G*, 6-31+G*, 6-311+G**, aug-cc-pVDZ, and aug-cc-pVTZ basis sets. CSIRO 2011.
- Iriarte, Ana G.,Cutin, Edgardo H.,Auergello, Gustavo A.
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Read Online
- Selective reduction of a C–Cl bond in halomethanes with Et3GeH at nanoscopic Lewis acidic Aluminium fluoride
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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
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p. 234 - 241
(2017/09/12)
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- A trifluoro methane resource utilization method
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The invention discloses a method for resource utilization of fluoroform. The method is characterized by mixing fluoroform with one or a plurality of halohydrocarbon, converting the mixture into a product containing monochlorodifluoromethane in the presence of a catalyst, and reacting unreacted fluoroform with other reaction products in a reactor. According to the method, chlorofluorocarbon containing chlorine or bromine or chlorofluorocarbon which contains chlorine or bromine and needs to be processed during a production process is utilized as reaction material to perform chlorine/fluorine exchange reaction with fluoroform to prepare monochlorodifluoromethane, better economic benefits and social benefits are provided; and in products, monochlorodifluoromethane can be recycled though separation, remained waste gas does not need to be processed, and can still enter the reactor as gas reacted with fluoroform, the conversion rate of reactants is improved, and zero-discharge is realized.
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Paragraph 0019; 0028-0063
(2017/08/25)
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- A combination of three fluoromethane cracking process for preparing
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The invention provides a technique for preparing monochlorodifluoromethane by decomposing trifluoromethane. The technique comprises the steps of: feeding the raw materials trifluoromethane and methane chloride into a reactor filled with a catalyst in the mol ratio of 0.1-10, and carrying out a decomposition reaction at a temperature ranging from 150 to 350 DEG C for 3-30 seconds to obtain a mixture of trifluoromethane, methane chloride, dichloromonofluoromethane and monochlorodifluoromethane; obtaining monochlorodifluoromethane directly through separation, reacting dichloromonofluoromethane separated out with hydrogen fluoride to produce monochlorodifluoromethane, and separating out and recovering trifluoromethane and methane chloride in the mixture as the reaction mixture continuously. The method has the advantage that the harm on the environment caused by trifluoromethane emission is greatly avoided.
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Paragraph 0025; 0026; 0030
(2017/02/24)
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- The use of active carbon pretreated at 2173 K as a support for palladium catalysts for hydrodechlorination reactions
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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
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body text
p. 223 - 231
(2012/02/03)
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- Process for the manufacture of hydrochlorofluorocarbons using trifluoromethane as fluorinating agent
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The present invention provides a process for the manufacture of hydrochlorofluorocarbons comprising treating a hydrocarbon substituted with one or more chlorine atoms and optionally one or more fluorine atoms under elevated temperature with GHF3.
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Page/Page column 5-6
(2010/04/25)
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- PROCESS FOR THE MANUFACTURE OF CHLORODIFLUOROMETHANE
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A process is disclosed for the manufacture of CHClF2 which involves contacting CHCl3, HF and pentavalent antimony catalyst in the liquid phase; passing reactor vapor effluent to a reflux column to produce a reflux column vapor effluent of CHClF2 and HCl; passing the reflux column vapor effluent to a condenser to produce a condenser liquid effluent of CHClF2 and a condenser vapor effluent of CHClF2 and HCl; passing the condenser liquid effluent to the reflux column upper end; and recovering CHClF2 from the condenser vapor effluent. The concentration of CHCl2F and CHF3 in the condenser vapor effluent is controlled by: (i) controlling the temperature at a point within the lower third of the theoretical stages of the reflux column by controlling the heat input to the reactor liquid phase; (ii) controlling the pressure in the reactor, reflux column and condenser by controlling the rate at which the condenser vapor effluent is removed from the condenser; (iii) maintaining the reflux ratio of the condenser at a substantially constant value; and (iv) maintaining the reactor liquid phase at substantially the maximum mass that does not result in entrainment or flooding of the reflux column. Also disclosed is CHClF2 which is a product of this process. Also disclosed is a refrigerant comprising CHClF2 and a method for its manufacture, a polymer foam blowing blend comprising CHClF2 and a method for its manufacture, fluoromonomers tetrafluoroethylene and hexafluoropropylene produced by using CHClF2 and a method for their manufacture, and a fluoropolymer produced by using CHClF2 as a fluoromonomer precursor and a method for its manufacture; all involving the manufacture of CHClF2 in accordance with the above process.
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Page/Page column 20-22
(2008/06/13)
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- Methane and methyl chloride as selective reducing agent in the transformation of hydrochlorofluorocarbons or chlorofluorocarbons to hydrofluorocarbons
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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.
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Page/Page column 6-7
(2008/06/13)
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- Nitrogen trifluoride as an oxidative co-reagent in high temperature vapor phase hydrofluorinations
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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
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p. 816 - 820
(2008/03/27)
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- PYROLYSIS PROCESS
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The present invention relates to the pyrolysis of hydrochlorofluorocarbons to form fluoromonomers such as tetrafluoroethylene, the pyrolysis being carried out in a reaction zone lined with nickel and mechanically supported by a jacket of other corrosion resistant metal, the nickel lining providing an improved yield of valuable reaction products.
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Page/Page column 4-5
(2008/06/13)
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- PROCESS FOR PURIFYING PENTAFLUOROETHANE, PROCESS FOR PRODUCING THE SAME, AND USE THEREOF
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ABSTRACT A process comprising bringing crude pentafluoroethane containing at least one compound selected from the group consisting of hydrofluorocarbons containing one carbon atom, hydrochlorofluorocarbons containing one carbon atom and hydrochlorocarbons containing one carbon atom, into contact with an adsorbent comprising a zeolite having an average pore size of 3 to 6 ? and a silica/aluminum ratio of 2.0 or less and/or a carbonaceous adsorbent having an average pore size of 3.5 to 6 ?, to reduce the content of the compound. The purified gas can be used as a low temperature refrigerant or an etching gas.
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- CONVERSION OF FLUOROCARBONS
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A process is disclosed for the conversion of fluorocarbons into fluorinated unsaturated compounds useful as monomers or other chemical precursors, such as C2H2F2. The process comprises reacting a hydrocarbon feed (20) and a fluorocarbon feed (10) in a high temperature reactor (26), at sufficiently high temperature and sufficiently short resident time to form a reaction product mixture (28) having the fluorinated unsaturated compound as the major reaction product, and cooling (18) to a temperature sufficiently low to inhibit polymerisation of the unsaturated compound. The reaction product may then be processed by removal of higher molecular weight compounds (35) and acids (32) and optionally separated (44) into product components.
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Page column 7-10
(2008/06/13)
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- Materials and methods for the conversion of hydrofluorocarbons
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Methods and materials are disclosed for the recovery of valuable hydrofluorocarbons and subsequent conversion to environmentally inert compounds. More specifically methods and materials are provided for recovering hydrofluorocarbons such as HFC-227, HFC-236, HFC-245, HFC-125, HFC-134, HFC-143, HFC-152, HFC-32, HFC-23 and their respective isomers. Processes are provided for converting hydrofluorocarbons such as these to fluoromonomer precursors such as CFC-217, CFC-216, CFC-215, CFC-115, CFC-114, CFC-113, CFC-112, HCFC-22, CFC-12, CFC-13 and their respective isomers. Materials, methods and schemes are provided for the conversion of these fluoromonomer precursors to fluoromonomers such as HFP, PFP, TFP, TFE, and VDF.
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- Gas-phase reaction of CCl2F2 (CFC-12) with methane.
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Gas-phase reaction of CFC-12 (CCl2F2) with methane was carried out in a plug flow reactor over the temperature range of 873-1123 K. The major organic halocarbons formed during the reaction were C2F4, C2H2F2, CHClF2, CH3Cl, C3H2F6 and CCl3F. The formation of all products except C2H2F2 decreased with temperature, while the selectivity to C2H2F2 (difluoroethylene) increased with temperature and reached approximately 80% at 1123 K. Under these reaction conditions, methane acts as hydrogen and carbon source, resulting in the formation of an unsaturated C2 hydrofluorocarbon from two C1 precursors.
- Uddin, Md Azhar,Kennedy, Eric M,Dlugogorski, Bogdan Z
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p. 1189 - 1191
(2007/10/03)
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- Process for the manufacture of defluoromethane
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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.
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Page/Page column 6-7
(2008/06/13)
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- The radiation chemistry of acyclic hydrofluoro and perhalogenated ether and hydrocarbon compounds
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The radiolytic stability of some hydrofluoroethers and hydrofluorocarbons was investigated and compared with those of perfluoropolyethers (PFPEs) and the CCl2FCClF2 (CFC 113). The experimental results indicate that stability depends mainly on the relative abundance of hydrogen atoms in the molecule; however, a significant role is played also by the chemical structure (i.e. the relative positions of the hydrogen atoms in the molecule). As a result, molecules containing hydrogen atoms as -OCF2H chain ends show a higher stability compared with the other hydrofluoro compounds. Based on the analysis of the end products and on the nature of radicals detected by EPR, radiolysis mechanisms are proposed and discussed. Due to their high dipole moments the hydrofluoro compounds and CCl2FCClF2 degrade mainly through an ionic mechanism.
- Marchionni, Giuseppe,Guarda,Buttafava,Faucitano, Antonio
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p. 153 - 162
(2007/10/03)
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- Hydrodechlorination of dichlorodifluoromethane over novel CrF3 supported palladium catalysts
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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
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p. 1607 - 1611
(2007/10/03)
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- Fluorinated phosphonium ylides: Versatile in situ Wittig intermediates in the synthesis of hydrofluorocarbons
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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.
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- Characterization and reactivity of Pd/MgO and Pd/?3-Al2O3 catalysts in the selective hydrogenolysis of CCl2F2
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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
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p. 1024 - 1031
(2007/10/03)
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- Magnesium fluoride as a catalytic support in hydrodechlorination of CCl2F2 (CFC-12)
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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
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p. 685 - 686
(2007/10/03)
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- PROCESSES FOR PREPARING 2'-DEOXY-2'-FLUOROCOFORMYCIN AND STEREOISOMERS THEREOF
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2'-Deoxy-2'-fluorocoformycin and 2'-deoxy-8-epi-2'-fluorocoformycin are synthesized in this invention through a multi-stage process via 3,5-di-O-benzoyl-2-deoxy-2-fluoro-alpha- and -beta-D-ribofuranosyl bromides. Further, according to this invention, 2'-deoxy-2'-epi-2'-fluorocoformycin and 2'-deoxy-8,2'-diepi-2'-fluorocoformycin are synthesized by a multi-stage process starting from 3,5-di-O-benzoyl-2-deoxy-2-fluoro-alpha-D-arabinofuranosyl bromide. These four 2'-fluoro derivatives of coformycin are novel compounds and have high enzyme-inhibitory activities against adenosine deaminase. In particular, these novel compounds are useful substances which exhibit therapeutic effects on acute lymphocytic leukemias due to their high enzyme-inhibitory activities above-mentioned. In addition, a variety of intermediates are obtained as novel compounds which are useful for the synthesis of the aforesaid novel 2'-fluoro derivatives of coformycin.
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- Preparation of and fluoroalkylation with (chlorodifluoromethyl)trimethylsilane, difluorobis(trimethylsilyl)methane, and 1,1,2,2-tetrafluoro-1,2-bis(trimethylsilyl)ethane
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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.
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p. 1572 - 1581
(2007/10/03)
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- Mechanistic study of the selective hydrogenolysis of CCl2F2 (CFC-12) into CH2F2 (HFC-32) over palladium on activated carbon
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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.
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p. 505 - 510
(2007/10/03)
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- Gas-phase reactions of silicon-centred intermediates with chlorofluorocarbons
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Pyrolysis of pentamethyldisilane in the presence of a CFC, dichlorodifluoromethane, efficiently replaced chlorine by hydrogen in the CFC, with concomitant formation of chlorosilanes. Although the primary intermediate in this pyrolysis is dimethylsilylene, there was strong evidence that conversions resulted from reactions of organosilyl and alkyl radicals. Experiments to confirm this conclusion are described, and mechanisms are discussed. Two independent measurements of the activation energy difference between chlorine-and fluorine-abstraction from dichlorodifluoromethane by trimethylsilyl radicals gave concordant values of 52 ± 5 kJ mol-1. The reactions described are of interest in relation to the environmental importance of dechlorinating CFCs.
- Clarke, Michael P.,Conqueror, Martin,Morgan, Geraint H.,Davidson, Iain M.T.
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p. 395 - 396
(2007/10/03)
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- Selective fluorination of dichloromethane by highest oxidation state transition-metal oxide fluorides
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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.
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p. 105 - 107
(2007/10/03)
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- INVESTIGATIONS IN THE REGION OF INDUSTRIAL FLUORINATED COMPOUNDS
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The synthesis and properties of ozone-friendly fluorohydrocarbons, fluoroolefins, and fluorinated compounds with functional groups (acids, alcohols, esters, and others), used for the creation of effective surfactants, ion-exchange membranes for various purposes, heat-resistant oils, and greases, were investigated.A technology was developed for the production of highly pure fluorinated compounds for microelectronics, fiber optics, and medicine.
- Maksimov, B. N.
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p. 1935 - 1940
(2007/10/03)
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- Thermal Gas Phase Hydrodehalogenation of Bromochlorodifluoromethane
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The thermal hydrodehalogenation of bromochlorodifluoromethane (Halon-1211; CBrClF2) in the gas phase has been studied using a plug flow alumina reactor at atmospheric pressure over the temperature range 400-900 degC with residence times of 2-3 s and CBrClF2/hydrogen molar intake ratios of ca. 10.Conversion of CBrClF2 starts at ca. 400 degC with C-Br bond homolysis followed by reaction with HX (X being Br, Cl or H) to yield CHClF2.At higher temperatures other products arise and complete conversion of CBrClF2 is achieved at ca. 600 degC.At temperatures above 850 degC complete dehalogenation to mainly methane (yield 80percent) is attained.In the temperature range 450-550 degC the (pseudo) first-order rate constant for the overall reaction (F) was found to obey: log (kF/s-1) = (9.4 +/- 1.5) - (150 +/- 25) kJ mol-1/2.303RT.The thermolysis of CBrClF2 was also studied using an excess of 2-phenylpropane (cumene) as a radical scavenger, resulting in the following Arrhenius expression for reaction (G): log (kG/s-1) = (15.1 +/- 0.5) - (262 +/- 9) kJ mol-1/2.303RT.From these parameters the bond dissociation energy for the C-Br bond in CBrClF2 was calculated to be 268 +/- 8 kJ mol-1, leading to a heat of formation of the CClF2-radical of -279 +/- 17 kJ mol-1.Kinetic analysis and separate experiments with H2O2 as an initiator for making H-radical showed that attack by H-radical is the main route for decomposition of CBrClF2.At temperatures higher than 500 degC HBr rather than H2 acts as a hydrogen transfer agent resulting in a fast radical chain (reactions G and L-O) with the observed Arrhenius parameters as a consequence.
- Lijser, Huub J. P. de,Louw, Robert,Mulder, Peter
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p. 139 - 146
(2007/10/02)
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- High Oxidation State Binary Transition Metal Fluorides as Selective Fluorinating Agents
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High oxidation state transition metal fluorides are selective fluorinating agents for dichloromethane, those with d0 electronic configurations undergo hydrogen-fluorine exchange and metal reduction, while dn species undergo chlorine-
- Dukat, Wolfgang W.,Holloway, John H.,Hope, Eric G.,Rieland, Matthias R.,Townson, Paul J.,Powell, Richard L.
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p. 1429 - 1430
(2007/10/02)
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- Synthesis of functionalized polyfluoroalkyl hypochlorites and fluoroxy compounds and their reactions with some fluoroalkenes
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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.
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p. 129 - 150
(2007/10/02)
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- The reactions of xenon difluoride with "inert" solvents
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The reactions of XeF2 with a variety of organic solvents are dscribed.XeF2 is found to undergo both hydrogen-and chlorine-fluorine exchange over a relatively short timescale with chloroform, dichloromethane and dibromomethane.XeF2 reacts very slowly with tetrachloromethane and fluorotrichloromethane, although the addition of a catalitic amount of Hf increases the rate of reaction considerably.XeF2 dissolves in acetonitrile with negligible reaction to the extent of 2.25 mol kg-1.
- Dukat, Wolfgang W.,Holloway, John H.,Hope, Eric G.,Townson, Paul J.,Powell, Richard L.
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p. 293 - 296
(2007/10/02)
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- Reduction of polyhalofluoroalkanes with formate to hydrogen-bearing alternatives initiated by carbon dioxide anionic radical
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Reduction of polyhalofluoroalkanes with formate in the presence of a catalytic amount of persulfate is described.Such a reagent posseses good selectivity in the reduction of carbon-chlorine bonds.A chain mechanism including carbon dioxide anionic radicals and polyhalofluoroalkyl radicals is proposed.
- Hu, Chang-Ming,Tu, Ming-Hu
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p. 105 - 108
(2007/10/02)
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- Multiphoton Dissociation of C3F6 and CF2HCl
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Multiphoton dissociation experiments in perfluoropropene and difluorochloromethane have been carried out with one or two wavelengths.It is shown that the increase of selectivity induced by a nonresonant radiation is attributable to an enlagement of the unimolecular reaction regime.The behaviour of large and small molecules when irradiated with two IR laser beams is different.Whereas the distinguishability between unimolecular and collisional regimes is enhanced for sufficiently large molecules, it tends to be smoothed in the case of small molecules.
- Santos, M.,Sigueenza, C.,Torresano, J. A.,Gonzalez-Diaz, P. F.
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p. 455 - 458
(2007/10/02)
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- A New HCN Production from CCl2F2 (CFC12) and Ammonia over NiTiO3, Ni metal, and Pt/C Catalysts
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NiTiO3, Ni metal, and Pt/C are effective catalysts for the formation of HCN from CFC12 and NH3 at 673-823 K: 86.2percent yield is attained at 723 K over Ni metal.
- Takita, Yusaku,Ishihara, Tatsumi,Hashida, Masayo
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p. 1247 - 1248
(2007/10/02)
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- KINETICS OF CHLOROFORM FLUORINATION BY HF CATALYZED BY ANTIMONY PENTACHLORIDE
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It is shown that SbCl4F can be considered as the main fluorinating agent when HF and SbCl5 are used in fluorination with an HF/SbCl5 ratio of 1:1.A very simple way for preparing SbCl4F is described in the paper.Kinetic runs, performed in batches using both SbCl4F and HF+SbCl5 as fluorinating agents, allowed identification of the reaction pattern for the chloroform fluorination.Fluorination proceeds through four consecutive steps in which the first and the second are fast and reversible reactions, corresponding to the fluorine-chlorine exchange between HF/SbCl5 and SbCl4F/ChCl3 respectively.The main product, CHClF2 is formed in the third reaction.The last step to CHF3 is very slow.Assuming the formation of CHClF2 as reference, the relative reaction rates for the steps are: 150/7/1/0.03. Kinetic equations and parameters obtained by fitting batch runs have also been verified by interpreting experiments performed under steady state conditions.The kinetic model, employed for elaborating both batch and continuous runs, takes into account also the vapour-liquid equilibria for reactant and products.Suggestions are made on the reaction mechanisms.
- Santacesaria, E.,Serio, M. Di,Basile, G.,Carra, S.
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- Perfluoro- and Polyfluorosulfonic Acids. 21. Synthesis of Difluoromethyl Esters Using Fluorosulfonyldifluoroacetic Acid as a Difluorocarbene Precursor
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Difluoromethyl alkanoates 5 and fluorinated and nonfluorinated alkanesulfonates 9 were synthesized in moderate yields by the reaction of alkali metal salts of acids with fluorosulfonyldifluoroacetic acid (3) in acetonitrile under mild conditions.The presumed intermediate anion FO2SCF2CO2- generates CF2: by elimination of SO2, CO2, and F-.The esters are formed by insertion of CF2: into the O-H of the acid, whereas HCF3 is formed by the competing capture of F-.Organic acids can be used indirectly in the reaction in the presence of inorganic salts such as Na2SO4 and KCl, with comparable yields of difluoromethyl esters.
- Chen, Qing-Yun,Wu, Sheng-Wen
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p. 3023 - 3027
(2007/10/02)
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- Kinetics and Mechanism of the Gas-phase Thermal Bromination of Difluorochloromethane
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We have studied the kinetics of the gas-phase thermal bromination of difluorochloromethane in the dynamic regime at 613-693 K.The form of the kinetic equation has been established for conversions of the difluorochloromethane not greater than 20percent.The absolute value of the rate constant of the bromination reaction has been determined.The energy of the C-H bond in difluorochloromethane has been calculated.
- Zhdanov, G. F.,Poluektov, V. A.,Belevtsev, E. G.,Orlov, G. D.
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- Reactivity of Fluorochloromethanes with Desert Sands
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Desert sand reactivity with halocarbons like CCl3F (F11), CCl2F2 (F12) and CHCl2F (F21) has been proved.Reactivity increases in the sense: F12 F21 F11 and is favoured by temperature and short activation of samples at 673 K.For F11, the main reaction products are CCl4 and COCl2, but some transformation to F12 has been observed too.An influence of the desert sand origin (i. e. of its phase composition) has been also found. - X-ray photoelectron spectra of samples after reaction show the presence of F and Cl on their surface, mainly as calcium halides, and in direct proportionality with reactivity.
- Benzoni, L.,Garbassi, F.
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p. 379 - 382
(2007/10/02)
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- Cosmetic compositions for treating hair
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This invention relates to cosmetic tetrapolymer or higher polymer compositions useful as lacquers and setting lotions.
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- HEAT OF FORMATION OF THE CF2CL. RADICAL
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The difference in the energies of activation, combined with known thermochemical data gives a value for the heat of formation of the CF//2Cl. radical of 64. 3 kcal and a value for D(CH//2Cl-H) of 103. 8 kcal. Combination of this value with the measured appearance potential of (CF//2Cl) cation from CF//2Cl//2 gives a value for the ionization potential of the CF//2Cl. radical of 9. 1 ev. Bond- dissociation energies in several molecules containing the CF//2Cl. radicals have been determined from the appropriate appearance potentials of (CF//2Cl) cation.
- LEYLAND LM,MAJER JR,ROBB JC
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p. 898 - 900
(2008/10/08)
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