Carbon tetrafluoride, reaction

Carbon and Graphite. Fluorine reacts with amorphous forms of carbon, such as wood charcoal, to form carbon tetrafluoride [75-73-0], CF, and small amounts of other perfluorocarbons. The reaction initiates at ambient conditions, but proceeds to elevated temperatures as the charcoal bums ia fluoriae. 

Initial attempts at reactions between fluorine and hydrocarbons were described as similar to combustion and the reaction products contained mostly carbon tetrafluoride and hydrogen fluoride ... 

Tetrafluoroethylene undergoes addition reactions typical of an olefin. It bums in air to form carbon tetrafluoride, carbonyl fluoride, and carbon dioxide (24). Under controlled conditions, oxygenation produces an epoxide (25) or an explosive polymeric peroxide (24). Trifluorovinyl ethers,... 

Massonne, J. et al., Angew. Chem. (Intern. Ed.), 1966, 5, 317 Adsorption of nitrogen trifluoride on to activated granular charcoal at — 100°C caused an explosion, attributed to the heat of adsorption not being dissipated on the porous solid and causing decomposition to nitrogen and carbon tetrafluoride. No reaction occurs at +100°C in a flow system, but incandescence occurs at 150°C. 

Moissan attempted to harness elemental fluorine for organic synthesis, but found that he could not control the reactions, as combustion or detonation usually occurred.1 From carbon itself (and also in other ways), he claimed to have made carbon tetrafluoride, but this was not correct as the quoted boiling point was far too high. In fact, the isolation of fluorine had virtually no impact on the synthesis of organic fluorides for over 40 years. 

Lebeau and Damiens, and Ruff and Keim, both reported isolation of carbon tetrafluoride as the major product of the reaction of fluorine with carbon at high temperatures. 

Miller. Calfee and Bigelow made 1,1,2,2-tetrachlorodifluorOethane from a vapor-phase reaction of fluorine/nitrogen mixtures with hexachloroethane or tetrachlorocthene over copper gauze. Calfee and Bigelow fluorinated ethane likewise, obtaining hexafluoroethane and carbon tetrafluoride. 

The first long-lived fluorine-containing carbocation was discovered by Olah and coworkers.32 Thus, the fluorodimethylcarbcnium ion [Me2CF+] was obtained by protonation of 2-fluoropropene and also from 2,2-difluoropropane by reaction with antimony(V) fluoride. In the course of these investigations it was found that a-F stabilizes a cationic state, whereas fi-F is destabilizing. Attempts to prepare the simplest member of this class, the trifluoromethyl carbocation CF3+ failed. The ionization of trifluoromethyl halides with antimony(V) fluoride at — 80 C yielded only carbon tetrafluoride. 

As shown in Table 1, with stable fluorine flow rate, at ideal partial pressure, and with control of the fluorination time and temperature, the desired product composition with carbon yield up to 96% can be obtained. Fluorination of carbon above 500 C typically gives low yields due to further fluorination to carbon tetrafluoride as shown by the reaction mechanism below.12... 

The active carbon (C ), produced by the disproportionation reaction, reacts immediately with available fluorine producing more carbon tetrafluoride, which dilutes the fluorine concentration, thereby decreasing the rate of reaction.12 Formation of carbon tetrafluoride releases a large amount of heat (436 kJ moF ), thereby providing more energy to the product reactor to create more carbon tetrafluoride. This process can become uncontrolled when the entire reactor contents deflagrate and an explosive reaction can occur. 

Carbon disulfide gives an essentially quantitative yield of carbon tetrafluoride (4) and sulfur on reaction with sulfur tetrafluoride at 450 C in the presence of arsenic(III) fluoride as catalyst. At lower temperatures and with boron trifluoride as catalyst, bis(trifluoromethyl) polysulfides 5 and 6 are formed.205... 

Since the time of the earliest work concerned with the reaction of hydrocarbons and fluorine in 1890 by Moissan (who isolated fluorine in 1886), numerous difficulties have been reported. According to Lovelace et al the action of fluorine on a carbon compound can be likened to a combustion process where the products are carbon tetrafluoride and hydrogen fluoride (1). 

The interaction of fluorine with an organic compound liberates a quantity of energy which is frequently of the order of magnitude of, or greater than, the energy which binds the carbon atoms in chains. It is estimated 63 that the addition of fluorine to a double bond liberates ldS calories per mole, whereas chlorine liberates only 30 calories. Careful control qf the temperature throughout the reacting masses is therefore essential. Even in the most favorable cases, much decomposition occurs and carbon tetrafluoride is frequently the main reaction product.62-6 ... 

Carbonyl fluoride can be prepared by any of several methods, including the conversion of carbonyl chloride to the fluoride by such reagents as hydrogen fluoride1 and antimony (III) fluoride.2 The direct combination of carbon monoxide and fluorine is another route to this fluoride, but carbon tetrafluoride is a by-product of the reaction.8 A particularly suitable laboratory preparation of carbonyl fluoride is the fluorination of carbon monoxide by silver (II) fluoride.4 This method, described below, gives directly carbonyl fluoride of rather high purity without recourse to a low-temperature distillation. 

The synthesis of tetrafluoroethene (I) from carbon and carbon tetrafluoride in an electric arc involves the addition of fluorine to difluoroacetylene in the second reaction step. ... 

TEE (molecular weight 100.02) is a colorless, tasteless, odorless nontoxic gas [11]. It is stored as a liquid (its vapor pressure at -20°C is 1 MPa) and polymerized usually above its critical temperature of 33.3°C (91.9°E) and below its critical pressure 3.94 MPa (571 psi). The polymerization reaction is exothermic. In the absence of air it disproportionates violently to yield carbon and carbon tetrafluoride. This reaction generates the same amount of energy as an explosion of black powder. The decomposition is initiated thermally therefore, the equipment used in handling and polymerization of TFE has to be without hot spots. The flammability limits are 14% to 43% TFE burns when mixed with air and forms explosive mixtures with air and oxygen. The ignition temperature is 600°C to 800°C (1112°F to 1472°F) [12]. When stored in a steel cylinder it has to be under controlled conditions and with a suit-... 

Oxygen dilluoride reacts rapidly with selected alkenes at low temperatures 40 however, per-fluoroalkenes are less reactive than the corresponding alkylalkenes and require either thermal or ultraviolet activation.41 The oxidation, which is a homogeneous chain reaction,42 of hexa-fluoropropene, tetrafluorocyclopropene, and perfluorobut-2-ene all give a variety of products such as carbon tetrafluoride. carbonyl difluoride, hexafluoroethane, oxiranes, and other oxidation products.41 This reaction is not useful for preparative organic work. 

The first pure and fully characterized perjluorocarhons (PFC) were obtained by the reaction of graphite with fluorine gas, yielding mainly carbon tetrafluoride [10]. An improved procedure, less prone to accidents, was reported by Simons and Block in 1937 - passage of fluorine over graphite impregnated with catalytic amounts of mercuric chloride furnished a mixture of various per-fluorocarbons in a controllable and reproducible reaction, proceeding steadily and without explosions [11]. 

Carbon tetrafluoride is extremely inert and may be prepared by the reaction of SiC and F2, with the second product, SiF4, being removed by passage through aqueous NaOH. Equation 13.36 shows a convenient laboratory-scale synthesis of CF4 from graphite-free calcium cyanamide (see structure 13.7) trace amounts of CsF are added to prevent the formation of NF3. 

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