Fluorocarbon conversion

Entries on new materials, including re-cyclate plastics, fullerenes, hard-surfaced polymers, dendrimers, transflective materials, rapid prototyping materials, silicone nitride, supercritical fluids, bulk molding compounds, conversion coatings, folic acid, replacements for chloro-fluorocarbons ... 

If solid polymer objects are fluorinated or polymer particles much larger than 100 mesh are used, only surface conversion to fluoropolymer results. Penetration of fluorine and conversion of the hydrocarbon to fluoropolymers to depths of at least 0.1 mm is a result routinely obtained and this assures nearly complete conversion of finely powdered polymers. These fluorocarbon coatings appear to... 

Uses. Conversion of uranium tetrafluoride to uranium hexafluoride oxidizer in rocket fuel systems manufacture of various fluorides and fluorocarbons... 

Conversely, the role of perfluorocarbons for oxygen transport and in vivo delivery is investigated. In addition to possible use as temporary blood substitute, these fluorocarbon molecules can be applied as respiratory gas carriers, for instance as lung surfactant replacement compositions for neonates and possibly for the treatment of acute respiratory distress syndrome for adults. Another... 

Carbon fluoride [also known as carbon monofluoride, polycarbon monofluoride, graphite fluoride, or (CFx)n] is a solid, layered, non-stoichiometric fluorocarbon of empirical formula CFX, where 0 < x < 1.25, obtained by the action of elemental fluorine on carbon. Fluorine combines with carbon and yields three solid compounds CFX, C2FX, and C4FX as well as varying amounts of volatile fluorocarbons as byproducts. With appropriate selection of fluorination conditions nearly 100% conversion of carbon to carbon tetrafluoride can occur. 

If solid polymer objects are fluorinated or polymer particles much larger than 100 mesh are used, only surface conversion to fluorocarbon results. Penetration of fluorine and conversion of the hydrocarbon to fluorocarbon to depths of at least 0.1 mm is a result routinely obtained and this assures nearly complete conversion of finely powdered polymers. These fluorocarbon coatings appear to have a number of potentially useful applications ranging from increasing the thermal stability of the surface and increasing the resistance of polymer surfaces to solvents and corrosive chemicals, to improving friction and wear properties of polymer surfaces. It is also possible to fluorinate polymers and polymer surfaces partially to produce a number of unusual surface effects. The fluorination process can be used for the fluorination of natural rubber and other elastomeric surfaces to improve frictional characteristics and increase resistance to chemical attack. 

Conversely, fluorine or fluorocarbon groups have a major effect in reducing the base strength of amines, ethers and carbonyl compounds for example, 2,2,2-trifluoroethylamine (pKb = 3.3) is ca. 10 times less basic than ethylamine. Also, pentafluoropyridine is only protonated in strong acid [6], whereas hexafluoroacetone is not protonated even in superacids [7-9] and perfluorinated tertiary amines and ethers are sufficiently non-basic for them to be used as inert fluids interchangeably with perfluorocarbons. 

Into a stainless steel reactor (i.d. 25 mm, length 400 mm) filled with K2C03 powder (82.3 g) at 200 C, was passed helium at a rate of 100 mL - min-1 and perfluoro(2-azepan-l-ylpropanoy fluoride) at a rate of4 g over 31 min after evaporation. The outlet gas was trapped at — 78 C to give 2.88 gofa fluorocarbon mixture. The mixture was almost pure product yield 2.88 g (84%, 100% conversion) bp 102-103 C. 

Photolytic decomposition of the fluorocarbon molecule augments the natural concentration of the Cl and CIO radicals, thereby accelerating the odd oxygen (ozone plus atomic oxygen) conversion to O2. 

Fluorine contamination has been reported in various environments and applications in the past. It has shown up in plasma processing [10-18], as crosscontamination from storage in contaminated containers or with contaminated samples [14,18], and modification of aluminum deposited on fluoropolymer substrates and other polymers having fluorine-based plasma treatments has also been observed [19-21]. Fluorocarbon lubricants have also been noted to modify the oxide structures on aluminum alloys [22,23], and the degradation of AI2O3 catalytic supports has been associated with fluoride conversion during reactions with fluorocarbons [24]. Alloy oxide modification has also been well noted in the presence of fluorine compounds not of the fluorocarbon family [25]. 

Direct electroreduction methods are typically used for dechlorination of chlorinated pollutants in waters. The easy removal of Cl from chlorinated organics allows conversion of chlorofluorocarbons (CFCs) into hydrochlorofluorocarbons (HCFCs), hydrofluorocarbons (HFCs), and even fluorocarbons (FCs). ECFCs are much less destructive to the atmospheric ozone than CFCs, but HFCs and FCs are harmless to atmospheric ozone, although they may contribute to the greenhouse effect. 

Table 2. Average ethylene conversion CO2, selectivity and fluorocarbons distribution over 5 pulses.

Perfluorination techniques have been developed for the conversion of many hydrocarbons to their perfluorinated counterparts. Fluorocarbons are chemically inert because of their kinetically unreactive carbon skeletons and have been considered as blood substitutes because of their high oxygen solubility. The thermal stability and low secondary bond forces of fluorocarbons have contributed to their use as greases, lubricants, and vapor-phase heat transfer reagents. 

Both states (Duschek, 2001) described are reversible and can be converted into each other (Figure 2). The high melting points of the fluorocarbon components are responsible for the fact that this conversion can only be carried out at elevated temperature, after the melting of the... 

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