Tetrafluoroethane, reaction

Difluoromethoxy-2-chloro-l,l,l-trifluoroethane and potassium fluoride produce 2-difluoromethoxy-1,1,1,2-tetrafluoroethane [50] The yield of the latter reaction is improved by adding a phase transfer catalyst or crown ether, tetra-methylammonium chlonde, tetrabutylammonium chloride, or 18-crown-6 with a solvent like sulfolane can be used for this purpose [5/] (equation 32)... 

Low concentrations of trifluoroacetate have been found in lakes in California and Nevada (Wujcik et al. 1998). It is formed by atmospheric reactions from 1,1,1,2-tetrafluoroethane and from the chlorofluorocarbon replacement compound CF3-CH2F (HFC-134a) in an estimated yield of 7-20% (Wallington et al. 1996). CF3OH that is formed from CF3 in the stratosphere is apparently a sink for its oxidation products (Wallington and Schneider 1994). 

Reaction to give tetrafluorooxathietane 2,2-dioxide (tetrafluoroethane sultone) had been used industrially and uneventfully, but reaction with excess sulfur trioxide may cause explosive decomposition to carbonyl fluoride and sulfur dioxide [1]. An incident involving the same explosion hazard was reported 11 years later [2], Use of inert gas to prevent explosion has been patented [3],... 

The specific radioactivity of the prepared [l- F]l,l,l,2-tetrafluoroethane is two to three orders of magnitude lower than expected for the specific radioactivity of the cyclotron-produced n.c.a [ F]fluoride. This implies that free fluoride is generated in the reaction (Scheme 65). 

When the addition is carried out in acetonitrile-dj, mono and di-deuterated [l-i F]l,l,l,2-tetrafluoroethanes are obtained, suggesting that the solvent acts as a source of protons. This reaction was the first demonstration of an efficient addition of [ F]fluoride to a fluoro-olefin it achieves the equivalent of the addition of hydrogen [ F] fluoride. 

Tetrafluoroethane-l,2-disulfenyl dichloride (83) reacts readily with At,iV-bis(trimethylsilyl)amines to give A -substituted tetrafluoro-l,3,2-dithiazolidines (84) (Scheme 16) <85CB281l>. The same type of products are obtained by reaction with a combination of trimethylsilyl azide and alkylarenes <89CB1071>. At a low temperature (83) was reported to be cyclized by NHj to 4,4,5,5-tetrafluoro-1,3,2-dithiazolidine <93JPC9625>. 

Young, Fukuhara and Bigelow repeated the vapor-phase reaction of fluorine/nitrogen mixtures with ethane, obtaining pentafluoroethane. 1,1.2,2-tetrafluoroethane. and 1,1,2-tri-fluoroethane, together with products of C — C bond fission. 

Acetonitrile gives99 very similar reaction mixtures over cobalt(III) fluoride (145 C) and potassium tetrafluorocobaltate(III) (400°C). The main product is fluoroacctonitrile (ca. 20% true yield) followed by 1,1,1,2-tetrafluoroethane (ca. 10%). Rhombohedral nickel(III) fluoride and potassium hexafluoronickelate(IV) in anhydrous hydrogen fluoride solution at — 20 to — 25 =C convert58 acetonitrile into trifluoroacetonitrile and 7V,7V-difluoropentafluoroethyl-amine, in a reaction reminiscent of the Simons electrochemical process. 

Much work has been done to develop catalyst systems that optimize yield and reduce side reactions. The reaction has an induction period, which depends on the temperature and the amount of catalyst.8 An early patent from Bayer claims that a nearly quantitative yield can be achieved in the conversion of l,2-dibromo-1-chloro-l.2.2-trifluoroethane(5) into 1,1-di-bromo-l-chloro-2,2.2-trifluoroethane (6) when aluminum tribromide is used in 2-broino-2-chloro-1,1,1-trifluoroethane (4) as solvent.12 A Japanese patent26 describes the activation of aluminum trichloride or alumina by pretreatinent with l,L2-trichloro-l,2,2-trifluoroethane (1) (see discussion of compound 19, vide infra). A later patent claims that aluminum trichloride and tribromide can also be activated by complexing with 1,1-dichloro- (CF3CFC12) and 1,1-dibromo-1,2,2,2-tetrafluoroethane (CF3CFBr2), respectively 2 an example of the latter is shown in the formation of bromofluoroalkane 10. 

As discussed (vide supra) disproportionation and isomerization are often competitive reactions. The reaction rates of both types depend on the temperature and the catalyst used for the reaction. Chromium(III) oxide on support, or without, favors the disproportionation of 1,1,2-trichloro-1.2,2-trifluoroethane to give l,l-dichloro-l,2.2,2-tetrafluoroethane and 1,1,1.2-tetra-chloro-2,2-difluoroethane whereas with aluminum trifluoridc the isomerization is favored.24 The higher the chlorine content of the molecules the greater is their reactivity. 

Chlonne-36-labeled 1,1-dichlorotetrafluoroethane is produced photochemically from chlonne-36 and l-chloro-l,2,2,2-tetrafluoroethane in better than 90% yield [22] Fluoroform is brominated to yield bromotrifluoromethane The reaction rate and yield are both enhanced by various catalysts, as summarized in Table 7 [23, 24, 25]. 

The reaction dynamics of multi-bond breakage during elimination of iodine from 1,2-diiodo-l,l,2,2-tetrafluoroethane has been the subject of femtosecond clocking in a supersonic molecular beam 59 the process proceeds via C2F4l+ and involves sequential C—I bond breakages taking 200 fs and 25 ps, respectively. 

Inaba et al. [29] have introduced a different cell to work with gaseous compounds (Fig. 4). A metal-plated solid polymer electrolyte (SPE) composite electrode faces the gas to be reduced. On the other side, the SPE is in contact with 0.1 M NaOH in which a Pt wire and an Ag/AgCl reference electrode are immersed. This system permits the electroreduction of insoluble reactants in water without employing organic solvents. For example, 2-chloro-l,l,l,2-tetrafluoroethane (HCFC 124) is transformed into 1,1,1,2-tetrafluoroethane (HFC 134a). The cathodic reaction can be written as follows ... 

Only little evidence has been found for ring expansion of the analogous phenylisocyanide complex 158b with HFA. The observation is in contrast to the reaction with hexafluoroisopropylideneimine (755). Compound 158a reacts with tetrafluoroethane eliminating HFA and forming a perfluorinated niccolacyclopentane (755). 

Oxathietane 2,2-dioxides (e.g., 448) are isolated in good yields from the reaction of sulfur trioxide with fluorinated alkenes, fluorinated dienes, ° and from the reaction of the sulfur trioxide donor 499 with fluorinated alkenes. Zwitterionic intermediates ( C-C-S020 ) are suggested. An explosion has been reported in the addition of sulfur trioxide to tetrafluoro-ethylene. Tetrafluoroethane /3-sultone (498) also is obtained by treatment of fluorosulfonyldifluoroacetic anhydride with antimony trichloride. ... 

Treatment of vicinal halogen compounds with sodium amalgam results in many cases in a reduction-elimination reaction 4,5-dibromovaleric acid thus forms 4-pentenoic acid on treatment with Na(Hg) [58]. l,l,2-Trichloro-l,2,2-trifluoroethane and 1,2-dichloro-l,l,2,2-tetrafluoroethane react with Na(Hg) similarly, with formation of 1-chloro-l,2,2-trifluoroethylene and tetrafluoroethylene, respectively [62,63]. 

In a dichlorodifluoromethane system, frictional wear exposed fresh metal surfaces on an aluminium compressor impellor, causing an exothermic reaction which melted much of the impellor. Later tests showed sunilar results, decreasing in order of intensity, with tetrafluoromethane chlorodifluoromethane bromotrifluoromethane dichlorodifluoromethane 1,2-di 11 uoro tetrafluoroethane ... 

The reactions of primary phosphines and the corresponding alkyl phosphides with a/ff-unsaturated ketones (25) have been discussed in some detail. " Tetrafluoroethylene with an excess of dimethylphosphine in the gas phase gives (26) by a reaction which is thought to be initiated by the bimolecular abstraction of a hydrogen atom from dimethylphosphine by tetrafluoro-ethylene. Tetrafluoroethylene also reacts with tetramethyldiphosphine by a radical process to give l,2-bis(dimethylphosphino)tetrafluoroethane (27). ... 

Chloro-5,5,6,6-tetrafluoro-5,6-dihydro-l, 4,2-dithiazine can be obtained in 4 % yield by reaction of tetrafluoroethane-l,2-disulfenic acid dichloride with anhydrous hydrogen cyanide (2 h, rt) 15... 

Perfluorinated 1,2-thiaphosphetanes 36 and 37 [37] have been obtained in two ways. The first method is based on the reaction of [bis(trimethylsilyl)]phosphines with l,l,2,2-tetrafluoroethane-l,2-bissulfenyl chloride (Scheme 19), which has... 

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