Tetrafluoroethene oxide

Examples of fluoride-ion-initiated reactions involving perfluorinated epoxides are shown in Figure 8.47 [155-158]. Hexafluoropropene oxide (HFPO) and tetrafluoroethene oxide will polymerise under certain conditions in the presence of fluoride ion. The process involves an extending alkoxide and it is terminated by elimination of fluoride ion to give... 

Infrared spectroscopy has been used for the quantitative determination of COF 3 in a mixture with tetrafluoroethene and hexafluorocyclopropane, resulting from the thermal decomposition of tetrafluoroethene oxide [1230]. The absorption band at ca. 950 cm was used for COF3 [1230] other workers have used r, [427a]. Quantitative measurement of... 

Carbonyl difluoride is the principal product of the oxidation of tetrafluoroethene by molecular oxygen, whether induced thermally, photolytically, or by ionizing (X-ray or y-ray) radiation. A comparison of the methods has been carried out for the gas phase in a static system, and the results are summarized in Table 13.2 [320]. Tetrafluoroethene oxide, CjF O (13.2), and hexafluorocyclopropane, (CF2)3 (13.3), are formed as additional gaseous products... 

Gaseous tetrafluoroethene oxide, CjF O, undergoes unimolecular decomposition at 115-140 C to give COF, FjC=CFj and perfluorocyclopropane at lower temperatures, isomerisation of the C F O occurs to form CF3C(0)F. The high temperature reactions can be accounted for by the following reaction scheme [1230] ... 

Many perfluoroaUphatic ethers and tertiary amines have been prepared by electrochemical fluorination (1 6), direct fluorination using elemental fluorine (7—9), or, in a few cases, by fluorination using cobalt trifluoride (10). Examples of lower molecular weight materials are shown in Table 1. In addition to these, there are three commercial classes of perfluoropolyethers prepared by anionic polymerization of hexafluoropropene oxide [428-59-1] (11,12), photooxidation of hexafluoropropene [116-15-4] or tetrafluoroethene [116-14-3] (13,14), or by anionic ring-opening polymeriza tion of tetrafluorooxetane [765-63-9] followed by direct fluorination (15). 

The known chemistry of the bisftrifluoromethyOnitroxyl [3i, 34] includes additions to both olefins [75, 36 37] and fluoroolefins [iaddition products with chlorotnfluoroethene or tetrafluoroethene [39] The nitroso denvative, (Cp3)3NONO, reacts with a liimted set of halogenated olefins to add the (CF3)2NO and NO moieties [40]... 

Table 3. Reaction of Tetrafluoroethene with an Oxidizing Agent and Catalysl...

Photochemically induced epoxidation of tetrafluoroethene by oxygen with improved yields (71-76%, conversion 21-62%) is achieved in the presence of radical generators such as tri-bromofluoromethane, 1,2-dibromotctrafluorocthane, ethyl nitrite or 1 H, /F,5//-octafluoropen-tyl nitrite.36 The oxidation of tetrafluoroethene with oxygen can also be catalyzed with bis(trifluoromethyl)diazene an undistillable viscous oil with peroxide composition is formed initially which can be quantitatively converted into carbonyl fluoride when heated.37-38... 

Hexafluoropropene (29) can be oxidized in a similar way as tetrafluoroethene, but it can also be oxidized by different methods. Gas-phase oxidations generally lead to mixtures of products. A mixture of products is obtained in the photoinitiated oxidation of 29 with oxygen in both the liquid and gaseous state in addition to low conversions into perfluoro(2-methyloxirane) (30) and other volatile compounds, a clear viscous polymer is obtained as the major product.46 The oxidation at low temperatures gives the epoxide as the dominant product,47 but the conversion is only 24%. Epoxide 30 is obtained in moderate yield, among other products, when a mixture of hexafluoropropene and oxygen difluoride is irradiated with UV light.48 Without irradiation, the mixture does not react at room temperature.48... 

Perfluoro-w-alkanes Perfluoro-cycloalkanes Perfluoro-w-alkanes Perfluorinated cyclic ethers Perfluorotrialkylamines Perfluoro-w-alkanes Perfluorinated cyclic ethers Perfluorotrialkylamines Homopolymers of hexafluoropropene oxide Photooxidation products of hexafluoropropene or tetrafluoroethene Homopolymers of tetrafluorooxetane... 

The most convenient route to lluorinatcd epoxides is the direct epoxidation of alkenes. Since first reports of a general method using alkaline hydrogen peroxide at low temperature,- several alternative synthetic approache.s have been developed. Molecular oxygen under free-radical conditions has been used to oxidize alkenes such as tetrafluoroethene or hexafluoro-propene however, internal epoxides are formed most conveniently using hypochlorites. The products, e. g. oxirane 14 from alkene 13, are usually obtained in high... 

Carbonyl difluoride is usually the major product of the oxidation of tetrafluoroethene, CFj=CF3, whether the oxidation is induced thermally, photochemically or by ionising radiation. 

Serious concern that some of the commonly used fluorocarbons may adversely affect the concentration of ozone in the stratosphere have prompted many studies of the oxidation of tetrafluoroethene to COF 3, with a wide range of oxidizing agents. 

The gas phase oxidation of tetrafluoroethene with an equimolar amount of dioxygen. Equation (13.6), takes piace at 200-450 "C in a flow system at contact times of 1-10 s. The... 

The thermal decomposition of tetrafluoroethene in shock waves is a convenient source of difluoromethylene radicals. Their oxidation with NO results in the reversible formation of CFjNO but, above 2500 K, the reaction proceeds further to equilibrium by the following reactions [1418] ... 

Carbonyl difluoride will react with partially oxidized charcoals to produce graphite fluorides, containing up to 10% fluoride [ICI29]. Treatment of carbonyl difluoride with carbon monoxide at temperatures in excess of 350 C and elevated pressures, and in the presence of a catalyst e.g. Fe or CuFj), is reported to generate tetrafluoroethene [842] ... 

TETRAFLUOROETHENE (116-14-3) Highly reactive, thermally unstable, flammable gas (flash point <32°F/<0°C). Explodes under pressure. Able to form unstable peroxides in air. If inhibitor (usually limolene) is not present in adequate concentrations, explosive polymerization may occur above 2025 mm Hg/2.66 bar at normal temperatures. Inhibited monomer will explode on contact with iodine pentafluoride and other substances, or in elevated temperatures. Violent reaction with chloroperoxytrifluoromethane, difluoromethyl-ene dihypofluorite, dioxygen difluoride, halogens, oxidizers, oxygen, sulfur trioxide, triboron pentafluoride. Incompatible with ethylene, hexafluoropropene forms an explosive peroxide. 

The ultimate product of the polymerization of the CF, unit is the solid known as poly(tetrafluoroethene) or PTFE (Teflon), used in non-stick surface coverings. In the polymer there are C-C linkages between the tetrafluoroethene monomer units. All the atoms obey the octet rule, all the carbon atoms are four-valent, and each of the fluorine atoms participate in one single bond. That the oxidation state of the carbon is +2 is very misleading. 

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