Fluorine carbon

An ipso attack on the fluorine carbon position of 4-fIuorophenol at -40 °C affords 4-fluoro-4-nitrocyclohexa-2 5-dienone in addtion to 2-nitrophenol The cyclodienone slowly isomenzes to the 2-nitrophenol Although ipso nitration on 4-fluorophenyl acetate furnishes the same cyclodienone the major by-product is 4 fluoro-2,6-dinitrophenol [25] Under similar conditions, 4-fluoroanisole pnmar ily yields the 2-nitro isomer and 6% of the cyclodienone The isolated 2 nitro isomer IS postulated to form by attack of the nitromum ion ipso to the fluorine with concomitant capture of the incipient carbocation by acetic acid Loss of the elements of methyl acetate follows The nitrodienone, being the keto tautomer of the nitrophenol, aromatizes to the isolated product [26] (equation 20) Intramolecular capture of the intermediate carbocation occurs in nitration of 2-(4-fluorophenoxy)-2-methyIpropanoic acid at low temperature to give the spiro products 3 3-di-methyl-8 fluoro 8 nitro-1,4 dioxaspiro[4 5]deca 6,9 dien 2 one and the 10-nitro isomer [2d] (equation 21)... 

Hydrolysis of geminal fluorides requires activation by per- or polyfluoroalkyl or perfluoroaryl groups and by double bonds linked to the same or adjacent carbon The activation is the result of reducing the electron density at the fluorinated carbon, facilitating attack by, primarily, nucleophilic reagents... 

Anode processes yield gaseous chlorine, fluorine, carbon chloride or fluoride. In the case of melts containing dissolved tantalum oxide, carbon oxides (mostly carbon dioxide) are formed on the graphite anode [28,37]. 

H and13C NMR Data. Some typical proton and carbon NMR data for trifluoromethyl ethers, sulfides, and esters are given in Scheme 5.11. Continuing the trend observed going from CH2F to CF2H to CF3 carbons, the 13C chemical shift of a trifluoromethyl ether is actually more shielded (by about 5 ppm) than that of a trifluoromethyl hydrocarbon. Scheme 5.12 summarizes the relative impact of an ether substituent upon the chemical shifts of various fluorinated carbons. 

T. Nakajima, S. Kasamatsu, Y. Matsuo, Synthesis and characterization of fluorinated carbon nanotubes, European Journal of Solid State Inorganic Chemestry, vol. 33, pp. 831-840,1996. 

II = CHa, CH2CH3, CH2CH2CH3, CH2CF3 = CH2CF3, CH(CF3)2 fluorinated carbonates Better low-temperature performance better SEI-formation ability lower inflammability. 466... 

Linear Solvents. For novel solvents that are intended to replace linear carbonates, the emphasis was placed on such properties as melting temperature, viscosity, and inflammability of the solvents. As Table 12 shows, these solvents can be roughly classified into four groups (1) linear esters or carbonates,(2) fluorinated esters,(3) fluorinated carbonates," and (4) fluorinated ethers." " ... 

Fluorinated carbonates were also used by Smart et al. as low-temperature cosolvents (Table 12), in the hope that better low-temperature performances could be imparted by their lower melting points and favorable effects on SEI chemistry. Cycling tests with anode half-cells showed that, compared with the ternary composition with nonfluorinated carbonates, these fluorinated solvents showed comparable and slightly better capacity utilizations at room temperature or —20 °C, if the cells were charged at room temperature however, pronounced differences in discharge (delithiation) capacity could be observed if the cells were charged (lithiated) at —20 °C, where one of these solvents, ethyl-2,2,2-trifluoroethyl carbonate (ETFEC), allowed the cell to deliver far superior capacity, as Figure 63 shows. Only 50% of the capacity deliverable at room temperature was... 

According to the authors, additional merits of such fluorinated carbonates would include their lower flammability and higher stability against storage at elevated temperatures as compared with their nonfluorinated counterparts therefore, the Incorporation of these novel solvents into the current commercial... 

The Hellmann-Feynman constraint has been applied successfully to the exocyclic fluorine, carbon, and nitrogen atoms in tetrafluoroterephthalonitrile (1,4-dicyano-2,3,5,6-tetrafluorobenzene). Charge balance is achieved without deterioration of the least-squares agreement factors, though the resulting changes in the density maps are very small (Hirshfeld 1984) (see chapter 5). 

Scheme 49. Enzyme-assisted [ F]fluorine-carbon bond formation using the recently discovered fluorinase.

The oxidative metabolism leads to the formation of reactive species (epoxides, quinone-imines, etc.), which can be a source of toxicity. Consequently, slowing down or limiting these oxidations is an important second target in medicinal chemistry. Thus, the metabolism of halothan (the first modern general anaesthetic) provides hepatotoxic metabolites inducing an important rate of hepatitis the oxidation of the non-fluorinated carbon generates trifluoroacetyl chloride. The latter can react with proteins and lead to immunotoxic adducts [54], The replacement of bromine or chlorine atoms by additional fluorine atoms has led to new families of compounds, preferentially excreted by pulmonary way. These molecules undergo only a very weak metabolism rate (1-3%) [54,55]. 

The chemistry occurring in a plasma by an injected fluorocarbon is critically dependent upon the effective fluorine/carbon ratio in the system.. We have seen that... 

The effective removal of fluorine from the system by the etching process to form stable volatile fluorides tends to lower the effective fluorine/carbon ratio in the plasma and, thus, increase the concentration of unsaturated species and therefore the polymerization rate (as discussed in a previous section) at the anode. 

A carbon-deposited film was prepared from the alumina film with 30-nm channels by the CVD technique using propylene. Fluorination was carried out by direct reaction of the film with dry fluorine gas (purity 99.7%). The film was placed in a nickel reactor and was allowed to react with 0.1 MPa of fluorine gas for 5 days at a predetennined temperature in the range of 50 to 200°C. Then the fluorinated carbon nanotubes were separated by dissolving the alumina film with HF. A schematic drawing of the fluorination process is given in Fig. 10.1.15. 

Fig. 10.1.17 Cls XPS spectra of (a) the fluorinated carbon deposited film and (b) the carbon nanotubes from the film (fluorination temperature 175°C). (From Ref. 42.)...

Per luoroethylene),F3C CF2 mw 100.02 col gas, fr p -142.5°, bp -78.4° insol in w. Was prepd by Humiston (Refs 1 2) by treating charcoal with fluorine carbon tetrafluoride was obtd at the same time. Accdg to Ref 3, it can be prepd by passing chlorodifluoromethane thru a hot tube. Serves as a raw material for prepn of polytetrafluoroethylene polymers... 

Fluorinated carbon, CFX, where x is between 0 and 1.3, is prepared by the direct fluorination of carbon at high temperatures [108]. Many varieties of fluorinated carbon can be prepared depending on the type of carbon used in the process (e.g. graphite, petroleum coke, carbon black, etc.) and the level of fluorination (i. e. the value of ). Fluorinated carbons, such as those manufactured by Allied-Signal (Accufluor ), Central Glass Co. (Cefbon ) and Daikin, are used for the fabrication of cathodes in lithium anode batteries and as solid lubricants [109]. 

Other groups can be attached to the fluorinated carbon atom. 

Quantitative characterization of plasma-polymer films, especially of ultrathin fluorinated carbon plasma polymer films, has been performed by ToF-SIMS to study changes in the surface composition and molecular distribution. CFX films on silicon and polyethylene terephthalate (PET) substrates were exposed to a pulsed Ar/CHF3 plasma by varying the deposition time from 10-90 s.111-113 The results show differences in film growth and CFX cross linking for the silicon and PET substrates.111... 

Tojo, T. Fluorine - Carbon and Fluoride - Carbon Materials Marcel Dekker New York. 1995 Chapter 9. 

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