Fluorocarbon Iodides

Perfluorocarbon iodides react with chlorosulfonic acid to give perfluorocarbon chlorosulfonates. For example, 1-iodoperfluoropropane 513 reacted with excess of the reagent (10 equivalents) under forcing conditions (in a sealed tube at 130 °C for 65 hours) to yield perfluoropropyl chlorosulfonate 514) (Equation 162).  

The fluorocarbon chlorosulfonates, e.g. 514, represent a new class of compounds and their formation by treatment of perfluoroalkyl iodides with chlorosulfonic acid appears to be a useful general preparative procedure. 

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It is claimed that addition of catalytic quantities of a quaternary ammonium salt greatly enhances both reactivity and yield [48] in the formation and subsequent reactions of (58). Tertiary fluorinated carbanions, generated from corresponding unsaturated precursors, react with a variety of electrophiles [46, 49,50] (Scheme 25), the most surprising being with fluorocarbon iodides, to give remarkable fluoride-bridged products, e. g. (60) [47],... 

Telomerisation of hexafluoropropene may be achieved using fluoroalkyl iodides as telogens [218, 219] this is rather surprising, considering that it is very difficult to achieve homopolymerisation of hexafluoropropene (Figure 7.62). It has been suggested [218] that these reactions may not be radical-chain processes but could involve successive four-centre additions of fluorocarbon iodides to the olefin (Figure 7.63). 

Two known synthesis routes were used to convert short-chained perfluoroalkylene dicarboxylic acid and diiodide intermediates to diaryl intermediates. The copper-catalyzed coupling of aryl and fluorocarbon iodides described by McLoughlin and Thrower (12) provided convenient synthesis of short-chained diphenylperfluoroalkylene compounds when appropriate fluorocarbon diiodides were available. The preparation of diaryl intermediates via aryl ketone synthesis and subsequent SF4 fluorination reaction provided a satisfactory alternative synthesis of lower-molecular-weight intermediates (13). 

When iodoarsines are coupled with fluorocarbon iodides in the presence of mercury, arsines and not arsonium derivatives are produced (67-70). 

Other trialkylarsines and fluorocarbon iodides have been found to behave similarly 176,177). 

Cleavage of As—As bonds by fluorocarbon iodides has already been described above. A related reaction is the cleavage of As—S bonds 178). 

The relationship between number average molecular weight and the yield of polymer formed in the presence of three kinds of fluorocarbon iodides, perfluoroisopropyl iodide, 1,4-di-iodo-perfluorobutane and 1,6-di-iodo-perfluorohexane is shown in Figure 2. The first fluorocarbon iodide is a mono-iodide type chain transfer agent the latter two are di-iodide type chain transfer agents. The relationship between number average... 

Fluorinated radicals play a significant role in synthetic organo-fluorine chemistry, for example, in electrophilic radical addition to alkenes, single-electron transfer reactions (SET), telomerization of fluoroalkenes with perfluoroalkyl iodides, polymerization to fluoropolymers and copolymers, and thermal, photochemical and radiation destruction of fluorocarbons. Furthermore, such free radicals are of interest for studying structures, reaction kinetics and ESR spectroscopic parameters.38... 

Fluorocarbon organometallic chemistry began with the first syntheses of perfluoroalkyl iodides (see Chapter 7, Sections EC, Subsection 7, and HE, Subsection 2, for current methods). On the basis of classical methods, this might have been expected to lead logically to the corresponding lithio derivatives and these, in turn, to a considerable... 

Perfluoroalkyl derivatives of mercury were the first fluorocarbon-organometallic compounds to be reported. Alkylmercurials are valuable in that they are able to alkylate other metals, but the toxicity of mercurials greatly inhibits the use of these systems. Perfluoroalkyl iodides react with mercury on heating or irradiation with ultraviolet light to give perfluoroalkylmercury(ll) iodides [58-60] (Figure 10.17). 

Surface tension studies of the most common fluorosilicone, poly(3,3,3-trifluoropropylmethylsiloxane) (PTFPMS), give unexpected results. Compared with (PDMS), PTFPMS has a higher liquid surface tension, a similar critical surface tension of wetting, and a considerably lower solid surface tension, as determined by water and methylene iodide contact angles and the method of Owens and Wendt (67). These results are summarized in Table X (7, 67, 72-74, 76, 77), in which PTFPMS is compared with two other fluorocarbon polymers, poly(tetrafluoroethylene) (PTFE) and poly(chlorotrifluoroethylene) (PCTFE). PTFE behaves like PTFPMS, whereas PCTFE behaves like PDMS. 

Two fascinating reports from Hughes and coworkers provide new perspectives on electrophilic attack on saturated fluorocarbons attached to cyclopenta-dienyl rhodium complexes. The first report [68] describes a perplexing observation in which T1(I) salts selectively abstract fluoride from a tertiary C-F bond on a cyclopentadienyl ligand whereas Ag(I) abstracts iodide from the rhodium metal center. 

Perfluoro- and polyfluoro-alkyl and -cycloalkyl chlorides, bromides, and iodides are encountered so often as starting materials, derivatives, solvents, products in mechanistic studies, by-products, etc., that it is impracticable to provide a comprehensive coverage of the relevant literature in one section. Readers with a particular interest in fluorocarbon halides are thus advised to browse widely through this volume. Additionally, some of the information collected on chloro- (including environmental effects), bromochloro-, and iodo-compounds has been relegated to appendices (pp. 43, 45, and 46). 

In the fluorocarbon field it was found that heating perfluoroalkyl iodides with arsenic gives a mixture of products (28a, 29,30,31). 

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