- CHEMICAL REACTIONS AND LASERS: ELEMENTARY STEPS AND COMPLEX SYSTEMS
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In recent years, various methods have been developed to observe and influence the course of chemical reactions using laser radiation.By selectively increasing the translational, rotational, and vibrational energies of the reaction partners with high intensity visible and UV lasers, direct insight can be gained into the molecular course of the breaking and the re-forming of chemical bonds.The production of free radicals by laser radiation can be used in chemical synthesis for the production of monomers.As example the kinetics of the UV-laser induced dehydrochlorination of CH3CClF2 is described.The application of linear and non-linear laser spectroscopic methods allows a non-intrusive observation of the interaction of transport processes with chemical reactions used with high temporal, spectral and spatial resolution.As a simple test system the ignition of O2-O3 mixtures by irradiation with a CO2 laser along the axis of a cylindrical vessel is considered.Mathematical simulation of the ignition process is simulated mathematically by solving the corresponding system of conservation equations.Experimental data are presented for velocity components of the flame front from IR-UV double resonance experiments and for the temperature history from infrared absorption measurements using tuneable diode lasers.
- Wolfrum, J.
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- Solvent effects in the fluorination of 1,2-dichloro-1,1-difluoroethane (R-132b) to 2-chloro-1,1,1-trifluoroethane (R-133a)
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Trichloroethylene has been found to act as a rate enhancing co-factor in the liquid phase, tantalum (V) halide catalyzed, fluorine-for-chlorine exchange reaction of 1,2-dichloro-1,1-difluoroethane (R-132b) to 2-chloro-1,1,1-trifluorethane (R-133a). Several trifluoromethyl substituted benzenes have also been found to be rate-enhancing solvents.
- Belter, Randolph K.,Bhamare, Nanaji K.
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- Catalytic fluorination of 1,1,1-trifluoro-2-chloro-ethane in the presence of oxygen over chromium based catalyst doped or not by zinc supported over partially fluorinated alumina
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The addition of zinc in low amount to chromium based catalyst supported over partially fluorinated alumina has a positive effect for the fluorination reaction of CF3CH2Cl in the presence of dioxygen in order to prevent the catalyst deactivation. However, under these operating conditions, the Deacon reaction by reaction with HCl produced by Cl/F exchanges could be involved. The formation of various by-products was observed corresponding to the addition of HCl or Cl2 into halogenated double bonds.
- Loustaunau,Fayolle-Romelaer,Celerier,Brunet
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- Heterogeneous catalyzed synthesis of 1,1,1,2-tetrafluoroethane from 1,1,1,2-tetrachloroethane - thermodynamics and reaction pathways
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1,1,1,2-Tetrachloroethane and its fluorinated derivatives, as well as trichloroethene, were fluorinated by hydrogen fluoride in the presence of a preconditioned chromia catalyst.The reaction pathways were derived under different conditions.Fluorinated haloalkanes are formed both by dehydrochlorination/hydrofluorination mechanisms as well as a chlorine/fluorine exchange mechanism.Thus, beside fluorinated alkanes considerable amounts of halo-olefins occur in the product mixture.A survey is given of the reaction pathways showing their dependence on the reaction conditions.These are discussed with respect to the calculated thermodynamic data. - Keywords: Heterogenous catalysis; Chlorofluorocarbon; Hydrofluorocarbon; Halocarbon; Fluorination; HFC-134a formation
- Kohne, A.,Kemnitz, E.
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- A study of trichloroethylene hydrofluorination using a kinetic model
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The kinetic features of catalytic hydrofluorination of trichloroethylene and 2-chloro-1,1,1-trifluoroethane on chromium fluoride/magnesium fluoride catalyst were studied. The effect of pressure and addition of various components of the reaction mixture at the reactor inlet was studied using the developed model.
- Dmitriev,Trukshin,Smykalov
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- Room-temperature Catalytic Fluorination of C1 and C2 Chlorocarbons and Chlorohydrocarbons on Fluorinated Fe3O4 and Co3O4
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A study of the room-temperature reactions of a series of C1 and C2 chlorohydrocarbon and chlorocarbon substrate molecules with fluorinated iron(II,III) oxide and cobalt(II,III) oxide has been conducted.The results show that fluorinated iron(II,III) oxide exhibits an ability to incorporate fluorine into the following substrates in the order: Cl2C=CCl2 > H2C=CCl2 > CH3CCl3 > CHCl3 > CH2Cl2 > CH2ClCCl3 > CCl4 > CHCl2CHCl2.The fluorinated cobalt(II,III) oxide gave the reactivity series CHCl3 > CCl4 > H2C=CCl2 > CHCl2CHCl2 > CH2Cl2 > CH3CCl3 > CCl2CCl2 > CH2ClCl3.Reactions of C1 chlorohydrocarbon or chlorocarbon probe molecules with fluorinated Fe3O4 gave predominately C1 chlorofluorohydrocarbon and chlorofluorocarbon products, respectively, whereas fluorinated cobalt(II,III) oxide produced predominately C2 chlorofluorohydrocarbon and chlorofluorocarbons.For fluorinated Co3O4 the distribution of C2 products obtained from C1 chlorohydrocarbon precursor molecules is consistent with the formation of radical intermediates at strong Lewis acid surfaces.C2 chlorohydrocarbons exhibit a fluorine for chlorine (F-for-Cl) exchange reaction through the catalytic dehydrochlorination of the substrate to the alkenic intermediate.The F-for-Cl exchange process was dependent upon the ability of the substrate material to undergo dehydrochlorination; the inability of a substrate to undergo dehydrochlorination results in the fluorination process proceeding through the formation of chlorocarbon or chlorohydrocarbon radical intermediates.
- Thomson, James
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- Preparation method of 1, 1-difluoro-2-vinyl iodide
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The invention discloses a preparation method of 1, 1-difluoro-2-vinyl iodide. The method comprises the following steps: (1) simultaneously introducing vinylidene fluoride and chlorine into a tubular reactor for reacting, condensing, and collecting the reaction product to obtain 1, 2-dichloro-1, 1-difluoroethane; (2) reacting the 1, 2-dichloro-1, 1-difluoroethane with KI in a solvent, after the reaction is finished, performing cooling, and discharging, drying the reaction liquid by distillation, and rectifying the obtained distilled liquid to obtain 1-chloro-1, 1-difluoro-2-iodoethane; and (3) reacting the obtained 1-chloro-1, 1-difluoro-2-iodoethane under the action of a magnetic catalyst, cooling and discharging after the reaction is finished, placing the reaction liquid in an external magnetic field to separate the catalyst, and rectifying to obtain the 1, 1-difluoro-2-ethylene iodide product. The method has the advantages of simple process, easily available raw materials, high yield and environmental protection.
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Paragraph 0032-0033; 0036-0037; 0040-0041; 0044-0045
(2021/08/28)
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- HALOGENATION PROCESS OF 1,1-DIHALOETHENE
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The present invention concerns a halogenation process, in which a 1,1- dihaloethene CX2=CH2 (I) with at least one halogenation agent. The invention concerns further a process for the manufacture of chlorodifluoroacetic acid chloride (CDFAC), which comprise the steps of (a) chlorination of VF2, and (b) an oxidation process. Another object of the present invention is a process for the manufacture of agriculturally or pharmaceutically active compounds, comprising the halogenation and/or oxidation process.
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Page/Page column 7
(2016/07/05)
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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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- Synthesis of 1,1,1-trifluoroethane by fluorination of 1-chloro-1, 1-difluoroethane
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The subject of the invention is the manufacture of 1,1,1-trifluoroethane by fluorination or 1-chloro-1,1-difluoroethane with anhydrous hydrofluoric acid. The reaction is carried out in the liquid phase and in the presence of a fluorination catalyst.
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- Generation of radical species in surface reactions of chlorohydrocarbons and chlorocarbons with fluorinated gallium(III) oxide or indium(III) oxide
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The reactions of C1 and C2 chlorohydrocarbons and chlorocarbons have been studied with the Lewis acid catalysts fluorinated gallium(III) oxide and fluorinated indium(III) oxide, respectively. Product analysis shows chlorine-for-fluorine exchange reactions together with the formation of 2-methylpropane and its chlorinated analogues 2-chloromethyl-1,3-dichloropropane and 2-chloromethyl-1,2,3-trichloropropane. Reactivities of the chlorohydrocarbon probe molecules show fluorinated gallium(III) oxide to be a stronger Lewis acid than fluorinated indium(III) oxide. The formation of the symmetrical butyl compounds is consistent with the generation of surface radical species and is also consistent with a 1,2-migration mechanism operating within radical moieties at the Lewis acid surface.
- Thomson
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p. 1881 - 1885
(2007/10/03)
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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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- Liquid phase fluorination process and fluorinated organic products resulting therefrom
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In an improved process and plant for carrying out liquid phase fluorination in the presence of a catalyst, consisting in reacting hydrofluoric acid and an organic starting material in a reaction zone, and in separating, in a separating zone, reactional mixture and at least one light fraction containing the desired fluorinated organic products and at least a first part of the sub-fluorinated organic products formed, and a heavy fraction that includes the remainder of the sub-fluorinated organic products formed, and further comprising partial condensation of the said light fraction in order to obtain a gaseous phase containing the desired fluorinated organic products and a liquid phase containing said first part of the said sub-fluorinated organic products, said heavy fraction being returned to said reaction zone and said liquid phase being returned as a reflux to the top of the separation zone, intermediate recovery is carried out at, or in the proximity of, the lower portion of said separation zone.
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- Reaction of Bistrifluoromethylaminosulphenyl Chloride with Fluoro-olefins and Hexafluorobut-2-yne under Free-radical Conditions
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Reaction of bistrifluoromethylaminosulphenyl chloride with unsymmetrical fluoro-olefins in daylight or under photochemical conditions gives both possible 1:1 adducts (ca. 1:1) arising from homolytic fission of the S-Cl bond.Addition to octafluorobut-2-ene and hexafluorobut-2-yne gives mixtures of the syn- and anti- adducts.
- Service, Colin F.,Tipping, Anthony E.
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p. 135 - 140
(2007/10/02)
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