Fluorocarbons, chemistry

Unsaturated fluorocarbons are much more reactive toward nucleophiles than then hydrocarbon counterparts owing to fluorme s ability to both stabihze carban ions and mductively increase the electrophihcity of multiple bonds and aromatic nngs Nucleophihc attack dominates the chemistry of unsaturated fluorocarbons, and the role of fluonde ion in fluorocarbon chemistry is analogous to that of the proton in hydrocarbon chemistry [129] Like the related electrophilic reactions for hydrocarbons, there are fluonde-promoted isomenzations and dimenzations (equation 9), oligomenzations (equation 10), additions (equation 11), and amomc Fnedel-Crafts alkylations (equation 12) that all proceed via carbamomc intermediates [729 7 7]... 

Tests on Simons fluorocarbons (vide supra) showed that they did not react with urani-um(VI) fluoride, so that materials for handling it could be based on the C —F bond system. A vast effort on fluorocarbon chemistry was then mounted preparative techniques were found, and scaled up for production. Two processes were developed 37 42,43... 

One concrete measure of the amount of knowledge which is currently available about fluorocarbon-transition metal complexes is that until recently the entire field could be comprehensively surveyed in one very short chapter in a larger review (9-12). Within the past few years, however, the volume of work has grown to the extent that this type of treatment is no longer possible. Therefore the present discussion narrowly focuses upon only one aspect of fluorocarbon chemistry the synthesis of compounds that contain trifluoromethyl groups bonded to transition metals. 

As a resirlt of the differences in polarity between the carbon fluorine and the carbon-hydrogen bond, fluorocarbon chemistry is wrought with more differences than similarities to hydrocarbon chemistry despite their similarities in van der Waal s radii (1.20 vs. 1.35 A). A great body of chemistry for the functionalized fluorocarbons has been developed in the areas of perfluoroalkenes, halofluoroalkanes, ethers, epoxides, peroxides, ketones, acids, and esters. 

Fluorocarbons. Fluorocarbons represent a large class of compounds, which could in principle encompass the known variety of hydrocarbon derivatives. For the extensive literature in this area a number of comprehensive works can be consulted.The focus of much fluorocarbon chemistry is technically organic chemistry and will not be covered here. The more inorganic aspects of carbon-fluorine chemistry such as the chemistry of simple fluorocarbons, oxyfluorides, and their derivatives will be covered. Trends in reactivity can often be generalized from small molecules to compounds with longer fluoroalkyl chains. 

Polyfluoroalkylation Some of the chemistry of polyfluoroalkyl anions, generated by reaction of fluoroalkenes with fluoride ion, was discussed in Chapter 7, where the analogy between the role of fluoride ion in fluorocarbon chemistry and the role of the proton in hydrocarbon chemistry was emphasised. This analogy has been extended to include reactions of polyfluorinated anions, generated in the same way, with activated poly-fluoro-aromatic systems in what may be regarded as the nucleophilic counterpart of Friedel-Crafts reactions [119] (Figure 9.50). 

As in the chemistry of the C-H bond, an important problem in organometallic fluorocarbon chemistry is to discover if further reaction chemistry is possible once a C-F bond is successfully attacked. Kiplinger and coworkers demonstrated [48] that the tungsten(II) metallacycles obtained from C-F activation can be... 

Theories and evidence to date suggests that surfaces which should be naturally resistant to the formation of the first two rain-resistant layers should be hard, smooth, hydrophobic, free of first period elements (for example, sodium), and have the lowest possible surface energy. These evolving requirements for low soiling surfaces suggest that surfaces, or surface coatings should be of fluorocarbon chemistry. 

Tp -based fluorocarbon chemistry of group 9 is in general underdeveloped, and only two reports document fluoroalkyl complexes of rhodium or iridium relevant to this discussion. However, as with cobalt, these materials do warrant separate consideration. 

The tendency is to replace the C8 fluorocarbon chemistry by C6 or C4 fluorocarbon products or even fluorine-free water repellents. Currently, new commercial DWOR finishes are coming onto the market based on short chain fluorocarbons (C6 or C4 fluorocarbon chemistry), hybrid systems, or they are fluorine free. 

Lemal, D. M. Perspective on Fluorocarbon Chemistry. The Journal of Organic Chemistry 2004, <59,1-11. 

Lemal DM (2004) Perspective on fluorocarbon chemistry. J Org Chem 69 1-11 Key BD, Howell RD, Criddle CS (1997) Fluorinated organics in the biosphere. Environ Sci... 

Perfluoroalkanesulphonic Acids and Related Compounds. Continued industrial interest in this area of fluorocarbon chemistry has ensured a steady flow of patent literature relevant to this Report, some of which has been included in a list at the end of this chapter (p. 287). 

Dresdner R, Tlumac F, Young J (1960) Fluorocarbon nitrogen compounds. V. Nitrogen trifluoride as a reagent in fluorocarbon chemistry. J Am Chem Soc 82 5831-5834... 

A. M. Doyle, A. E. Pedler, and J. C. Tatlow, J. Chem. Soc. (Q, 1968,2740. This information is included because work of this type is rare in fluorocarbon chemistry at the present time. 

Following its painstaking investigation of the benzene-cobalt trifluoride reaction, which played such an important part in the development of aromatic fluorocarbon chemistry, the Birmingham group has studied in some detail the fluorination of tetrahydrofuran with cobalt trifluoride and with potassium tetrafluorocobaltate(in) as a prelude to an investigation of poly-... 

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