- Catalytical production processes for making hydrohalopropanes and hydrofluorobutanes
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A process is disclosed for making hydrohalopropanes or hydrofluorobutanes. The process involves reacting a hydrofluoromethane with a fluoroolefin in the presence of an aluminum catalyst to produce a hydrohalopropane or a hydrofluorobutane. The hydrofluoromethane is CH2F2 or CH3F. The fluoroolefin is CF2═CF2, ClFC═CF2, or CF3CF═CF2.
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Page/Page column 3
(2008/06/13)
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- PHOTOCHLORINATION AND FLUORINATION PROCESS FOR PREPARATION OF FLUORINE-CONTAINING HYDROCARBONS
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A process is disclosed for increasing the fluorine content of at least one compound selected from halohydrocarbons and hydrocarbons. The process involves (a) directing light from a light source through the wall of a reactor to interact with reactants comprising chlorine and said at least one compound in said reactor, thereby producing a halogenated hydrocarbon having increased chlorine content by photochlorination, and (b) reacting said halogenated hydrocarbon produced by the photochlorination in (a) with HF; and is characterized by the light directed through the reactor wall being directed through a poly(perhaloolefin) polymer.
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Page/Page column 11; 12
(2008/06/13)
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- Catalytic synthesis of 1,1,1,2-tetrafluoroethane from 1,1,1,2-tetrachloroethane - A mechanistic consideration
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1,1,1,2-Tetrachloroethane and its fluorinated derivatives as well as trichloroethene are fluorinated by hydrogen fluoride in the presence of a pre-conditioned chromia catalyst. The reaction pathways are derived under different conditions. Fluorinated haloalkanes are formed both by dehydrochlorination/hydrofruorination mechanism as well as chlorine/ fluorine exchange mechanism. Thus, beside fluorinated alkanes considerable amounts of haloolefins occur in the product mixture. A survey is given on the reaction pathway showing dependence on the reaction conditions. It is discussed with respect to calculated thermodynamic data. Kinetic and mechanistic investigations of the isomerisation reactions of 1.1.2.2-tetrafluoroethane on a CFC-conditioned chromia catalyst are also presented. The desired 1.1.1.2- tetrafluoroethane can be obtained from its symmetric isomer in the presence of a chromia catalyst conditioned exclusively with chlorine-free fluorocarbons. Mechanistic information is obtained by employing DCl which behaves similar to HF during the consecutive isomerisation reaction of 1.1.2.2- tetrafluoroethane. Thus, it is most probable that dehydrohalogenation/hydrohalogenation processes (elimination/addition mechanism) are mainly responsible for the formation of the haloolefins and halocarbons observed on chromia.
- Kemnitz,Niedersen,Kohne
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p. 485 - 493
(2007/10/03)
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- REACTIONS OF HALOGEN FLUORIDES. X. FLUORINATION OF CHLORINE-SUBSTITUTED ALKANES WITH BROMINE TRIFLUORIDE
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Bromine trifluoride in Freon 113 readily substitutes the chlorine atoms in monochloroalkanes by fluorine, while in the presence of catalytic amounts of certain Lewis acids it is also capable of substituting the chlorine atoms in polychloroalkanes with the formation of the corresponding fluorides.Additions of tin tetrachloride make it possible not only to increase the reaction rate but also to increase the selectivity of fluorination.In some cases substitution of a primary chlorine atom is accompanied by hydride transfers.
- Kartashov, A. V.,Chuvatkin, N. N.,Boguslavskaya, L. S.
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p. 2276 - 2278
(2007/10/02)
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- REACTIONS OF HALOGEN FLUORIDES. VII. FLUORINATION OF UNSATURATED COMPOUNDS WITH BROMINE TRIFLUORIDE AND AN EQUIMOLAR MIXTURE OF BROMINE TRIFLUORIDE WITH MOLECULAR BROMINE
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The reactions of bromine trifluoride and an equimolar mixture of bromine trifluoride and bromine with halogen-substituted alkenes and methyl α-substituted acrylates were investigated.With sufficient dilution of the substrate by Freon 113 (20-25:1) it is possible to obtain the bromofluoro and difluoro adducts with good yiels.The best results (overall yields of fluorination products 80-83percent) were obtained with alkenes containing a halogen at the multiple bond; in the case of more reactive substrates the reaction becomes nonpreparative.The bromofluorination of E- and Z-1,2-dichloroethylenes and E- and Z-1,3-dichloropropenes with pure bromine trifluoride is antistereospecific.The bromofluorination of E- and Z-1,2-dichloroethylenes by the BrF3-Br2 system gives a mixture of diastereomeric bromofluoro adducts as a result of isomerization of the initial olefins in the presence of the bromine.The formation of the difluorides of the halogenated olefins is nonstereospecific and is accompanied by migration of the halogens.
- Boguslavskaya, L. S.,Chuvatkin, N. N.,Kartashov, A. V.,Ternovskoi, L. A.
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p. 230 - 236
(2007/10/02)
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- REACTIONS OF CHLORINE MONOFLUORIDE. REGIOSPECIFICITY AND STEREOCHEMISTRY OF THE SUBSTITUTION OF BROMINE ATOMS BY FLUORINE IN HALOGEN-SUBSTITUTED ALKANES AND ESTERS
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Under mild conditions without catalysts chlorine monofluoride substitutes bromine atoms for fluorine in bromine-substituted alkanes and esters.Electron-donating substituents promote the substitution reaction.The following sequence is observed in the reactivity of the bromine atoms at the carbon: tertiary > secondary > primary.Halogen atoms (Cl, F) at a carbon containing a bromine also promotes substitution of the latter by fluorine.The reactivity of the bromine atoms decreases in the following order: CCl2Br(CClFBr) > CHClBr(CHFBr) > CH2Br.An alkoxycarbonyl group at a carbon containing bromine prevents substitution.In a number of cases substitutive fluorination is accompanied by skeletal rearrangements and by migration of chlorine atoms.The stereochemistry of substitutive fluorination was studied for the case of the reaction of erythro- and threo-1-bromo-2-fluoro-1,2-dichloroethanes and 1,2-dibromo-1,3-dichloropropanes with chlorine monofluoride.The probable mechanism of the reaction is discussed.
- Boguslavskaya, L. S.,Chuvatkin, N. N.,Panteleeva, I. Yu.,Ternovskoi, L. A.
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p. 814 - 820
(2007/10/02)
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