Xn:Harmful;75-69-4Relevant articles and documents
Kinetics of tetrachloromethane fluorination by hydrogen fluoride in the presence of antimony pentachloride
Meissner, Egbert,Milchert, Eugeniusz
, p. 89 - 95 (2003)
Contradictory information concerning the kinetics of tetrachloromethane fluorination by anhydrous hydrogen fluoride in the presence of antimony pentachloride has been explained. The present studies were performed using a stainless steel autoclave. The exchange of the first chlorine atom was carried out in the temperature range of 35-95°C, with the molar ratio of HF/CCl4 varied within the range of 1.2-1.7 and at a constant molar ratio of SbCl5/Cl2 equal to 1.9. The degree of conversion of CCl4 to CCl3F and the reaction rate constant as a function of temperature fit to an Arrhenius straight line. The Arrhenius constants (pre-exponential factor) and the activation energy were determined. Studies concerning the exchange of the second chlorine atom, i.e. the conversion of CCl3F to CCl2F2 have been performed. The results of kinetic investigations were created in the same way. Based on these results it was found that the Arrhenius equation is fulfilled also in the second stage of the fluorination. The same slope of the straight lines confirms that the fluorination stages proceed according to the same mechanism with the same activation energy but with different pre-exponential factors. Several kinetic problems associated with the performance of the reactor can be solved on the basis of the equations derived. However, knowledge of CCl4 conversion as a function of time, temperature, catalyst concentration and the type of the reaction is required for this purpose. Such calculations enable the selection of the optimal process parameters.
Interaction of trichloromethane and tetrachloromethane with nitrogen trifluoride
Mukhortov,Pashkevich,Blinov,Kambur,Kambur,Petrov,Kurapova
scheme or table, p. 420 - 426 (2011/08/04)
Interaction of nitrogen trifluoride with trichloromethane and tetrachloromethane at temperatures in the range from 20 to 200°C and pressures of up to 6.0 MPa in the gas and liquid phases was studied.
PROCESSES FOR THE SYNTHESIS OF 3-CHLOROPERFLUORO-2-PENTENE, OCTAFLUORO-2-PENTYNE, AND 1,1,1,4,4,5,5,5-OCTAFLUORO-2-PENTENE
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Page/Page column 14, (2009/07/18)
Disclosed is a process comprising reacting CF3CF2CCI2CF2CF3 (CFC-41 -10mca) with hydrogen in the presence of a dehalogenation catalyst to produce CF3CF2CCI=CFCF3 (CFC-1419myx). Also disclosed herein is a process comprising reacting CF3CF2CCI=CFCF3 (CFC- 1419myx) with hydrogen in the presence of a dehalogenation catalyst to produce CF3CF2C≡CCF3 (octafluoro-2-pentyne). Also disclosed herein is a process comprising reacting CF3CF2CCI2CF2CF3 (CFC-41 -10mca) with hydrogen in the presence of a dehalogenation catalyst to produce CF3CF2C≡CCF3 (octafluoro-2-pentyne). In addition, a process for reacting CF3CF2C≡CCF3, in a pressure vessel, with a Lindlar catalyst and hydrogen to produce CF3CF2CH=CHCF3 (1,1,1,4,4,5,5,5-octafluoro-2- pentene) is disclosed.
Method for the preparation of high surface area metal fluorides
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Page/Page column 8, (2010/10/20)
The present invention is related to a method for preparing an amorphous metal fluoride of the formula MX+FX-δ comprising the steps of a) providing a precursor, whereby the precursor comprises a structure having a formula of Mx+F(x-δ)-yBy; and b) reacting the precursor with a fluorinating agent generating the amorphous metal flouride having a formula of Mx+Fx-δ, whereby M is selected from the group comprising metals of the second, third and fourth main group and any subgroup of the periodic table, B is a coordinately bound group; x is any integer of 2 or 3; y is any integer between 1 and 3; δ is 0 to 0.1; and x?δ>y.
Decomposition of dichlorodifluoromethane with simultaneous halogen fixation by vanadium oxide supported on magnesium oxide
Tamai, Tsukasa,Inazu, Koji,Aika, Ken-Ichi
, p. 1565 - 1574 (2007/10/03)
Dichlorodifluoromethane (CCl2F2, 1% in He) decomposition with simultaneous halogen fixation by vanadium oxide supported on magnesium oxide was studied at 723 K in a flow apparatus. The pretreatment condition and vanadium loading of supported vanadium oxide samples affected the CCl2F2 decomposition efficiency. Through characterization studies (XRD, IR, Raman, and XPS) and reference experiments, Mg 3(VO4)2 was revealed to be the active species to initiate CCl2F2 decomposition, leading to MgF 2, MgCl2, and CO2 formation. The model experiments also suggested a detailed mechanism that VOCl3 was formed from Mg3(VO4)2 by a reaction with CCl 2F2 or the major intermediate compound CCl4, and that VOCl3 reacted with MgO to regenerate Mg3(VO 4)2 and to promote chlorine fixation as MgCl2.
Enhanced dichlorodifluoromethane decomposition with selective fluorine absorption by acidic fluoriated magnesinm oxide
Tamai, Tsukasa,Inazu, Koji,Aika, Ken-Ichi
, p. 1239 - 1247 (2007/10/03)
CCl2F2 decomposition with simultaneous halogen absorption by partially fluorinated MgO (MgF2-MgO) was studied, focusing on the effects of the acidity of the surface. CCl2F 2 decomposition by MgF2-MgO was greatly promoted by fluorination of MgO at 10 mol% or higher. CCl2F2 decomposition was not a catalytic process over MgF2-MgO but basically a selective fluorine absorption reaction with MgO to form MgF2. Chlorine was released in the form of CCl4 regardless of reaction temperature and degree of fluorination of MgO due to low reactivity to CCl 4. NH3-TPD and pyridine adsorption experiments were carried out to characterize the acid sites on MgF2-MgO samples. The amount of acid sites became maximum for 10% MgF2-MgO and the strength of acid sites increased as fluorination proceeded. CCl2F2 decomposition was revealed to be initiated by Lewis acid sites on MgF 2-MgO formed by CCl2F2 decomposition as well as by fluorination with hydrofluoric acid aqueous solution. Thus, formation of the Lewis acid sites was considered to be the key step for efficient CCl 2F2 decomposition with selective fluorine absorption.
The radiation chemistry of acyclic hydrofluoro and perhalogenated ether and hydrocarbon compounds
Marchionni, Giuseppe,Guarda,Buttafava,Faucitano, Antonio
, p. 153 - 162 (2007/10/03)
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.
Transient puffs of trace organic emissions from a batch-fed waste propellant incinerator
Hart, John R.
, p. 559 - 569 (2007/10/03)
Emissions data have been obtained from a waste propellant incinerator. The incinerator is a dual fixed hearth, controlled air incinerator equipped with acid gas and particulate scrubbing. Puffing has been evident in this waste propellant incinerator by spikes in the CO concentration. Transient puffs of organics may travel down the combustion chambers and lead to stack emissions. The major conclusions from this study are that (1) transient puffs are formed due to the semi-batch feed nature of the combustion process (causing a local oxygen deficiency) and high water content of the desensitized propellant; (2) in batch-fed combustors, puffs can contribute to most of the organic emissions (which are relatively low) measured with US EPA sampling and analytical methods; (3) it is estimated that batch-fed combustion contributes up to 7-18 times more emissions than steady-state combustion will generate; (4) by applying dispersion analyses to determine the amount of oxygen deficiency in the flame zone, the combustion zone concentration of CO during batch-fed operation could be as high as 160,000 ppm, compared to a measured peak stack concentration of 1200 ppm CO; and (5) an organic sample is collected and averaged over at least a 2-h period that smooths out the transient peaks of organics emissions during batch-fed operation. For emissions that are associated with long-term potential health impacts, this is an appropriate sampling method. However, if a compound has a short-term potential health impact, it may be important to measure the time-resolved emissions of the compound.
The fluoromethyl ether sevoflurane as a fluoride source in halogen-exchange reactions 1
Rozov, Leonid A.,Lessor, Ralph A.,Kudzma, Linas V.,Ramig, Keith
, p. 51 - 54 (2007/10/03)
Fluoromethyl 2,2,2-trifluoro-1-(trifluoromethyl) ethyl ether (sevoflurane), fluoromethyl 1,1,2,3,3,3-hexafluoropropyl ether, and fluoromethyl 1,2,2,2-tetrafluoroethyl ether are found to be selective fluoride donors in some halogen-exchange reactions. For example, treatment of a mixture of a polychlorinated substrate and one equivalent of sevoflurane with a catalytic amount of antimony pentachloride gives a monofluorinated product and one equivalent of chloromethyl 2,2,2-trifluoro-1-(trifluoromethyl) ethyl ether as by-product.
Generation of radical species in surface reactions of chlorohydrocarbons and chlorocarbons with fluorinated gallium(III) oxide or indium(III) oxide
Thomson
, p. 1881 - 1885 (2007/10/03)
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.
