Perfluorination with elemental

Perfluorinated organic bromides can be oxidatively fluonnated with elemental fluorine to derivatives containing tn- [124] and pentavalent [/25 126 127] bromine in yields up to 42% Perfluoroheptylbromine tetrafluoride has been used to fluonnate double bonds in halogenated alkenes [127]... 

Like perfluorinated polymers, perfluorinated fluids are both chemically and thermally very stable. Originally developed during the Manhattan Project their commercial application dates from the 1960s. There are two major production methods, cobalt(III) fluoride fluorination of hydrocarbons and electrochemical fluorination. The first route involves the fluorination of a stirred or fluidized bed of cobalt(II) fluoride to cobalt(III) fluoride with elemental fluorine at... 

Numerous unsuccessful attempts to synthesize cyclopropanethione have been reported. Thermal or photochemical generation of the C3H4S species from different sources always leads to allene episulfide. Some representative experiments include (a) in vacuo pyrolysis of the sodium salt of 2,2,4,4-tetramethylthietanone tosylhydrazone (4) into the stable tetramethylallene episulfide (S), (b) pyrolytic extrusion of nitrogen from perfluorinated thiadiazoline 6, (c) in vacuo pyrolysis of spiro compound 8 into methylenethiirane (3), (d) the flash vacuum pyrolysis-microwave spectroscopic approach applied to spiro compounds 9 and 10, (e) pyrolysis of anthracene adduct 11 and tosylhydrazide salt 12, (f) thermolytic nitrogen extrusion from pyrazoline-4-thione 13, thermolysis of tetramethylallene episulfide (5) or pyrazoline 13 in dig-lyme solution, and photolytic nitrogen extrusion from pyrazoline 13, ° (g) thionation of methylenecyclopropanone 15, and (h) reaction of donor-acceptor substituted allenes 18 with elemental sulfur. ... 

The most important use of XV is its telomerization with fluoride ion to give a linear hydrofluoroacyl fluoride (XVI), that is fluorinated with elemental fluorine to give a linear perfluorinated polyether (XVIII), which is sold by Daikin as Demnum (Eq 13.18). Note that Demnum and Krytox are isomeric materials. In general, their properties are quite similar, but there are subtle differences in physical properties and in chemical stability in tribological applications. 

Preparation of the corresponding perfluoropolyethers requires a subsequent fluorination step to saturate double bonds and replace hydrogens in the "spacer" groups with fluorine. We have found that the partially fluorinated vinyl ethers produced in the polycondensation reaction undergo reaction with elemental fluorine to give the desired perfluorinated polyethers. Ultraviolet irradiation is required to replace the least reactive hydrogensl ]. 

A single-chaimel (500 pm x 500 pm x 70 mm) microreactor has been designed for use with elemental fluorine, both for selective fluorination and for perfluorination of organic compounds [61]. The addition of fluorine to the trifluorosulfur group leads to the pentafluoro derivative in 44% yield (Scheme 9.12). From the data indicating that... 

This reaction has often reached explosive proportions in the laboratory. Several methods were devised for controlling it between 1940 and 1965. For fluorination of hydrocarbons of low (1—6 carbon atoms) molecular weight at room temperature or below by these methods, yields as high as 80% of perfluorinated products were reported together with partially fluorinated species (9—11). However, fluorination reactions in that eta involving elemental fluorine with complex hydrocarbons at elevated temperatures led to appreciable cleavage of the carbon—carbon bonds and the yields invariably were only a few percent. 

Chemical Properties. A combination of excellent chemical and mechanical properties at elevated temperatures result in high performance service in the chemical processing industry. Teflon PEA resins have been exposed to a variety of organic and inorganic compounds commonly encountered in chemical service (26). They are not attacked by inorganic acids, bases, halogens, metal salt solutions, organic acids, and anhydrides. Aromatic and ahphatic hydrocarbons, alcohols, aldehydes, ketones, ethers, amines, esters, chlorinated compounds, and other polymer solvents have Httle effect. However, like other perfluorinated polymers,they react with alkah metals and elemental fluorine. 

In spite of the high effort focused on the carbon electrochemistry, very little is known about the electrochemical preparation of carbon itself. This challenging idea appeared in the early 1970s in connection with the cathodic reduction of poly(tetrafluoroethylene) (PTFE) and some other perfluorin-ated polymers. The standard potential of the hypothetical reduction of PTFE to elemental carbon ... 

In order to minimize the degradation of macromolecules, the choice of solvent is not a trivial matter. Hydrogen-containing solvents are obviously not suitable, but even halogenated ones such as CFC13 or CC12FCF2C1, usually stable to fluorine, can react violently with this element when irradiated at temperatures near 0°C. We chose two perfluorinated solvents that have been proven safe and suitable for radical fluorination perfluoro-2-(butyl)-tetrahydro-duran (FC-75 Fluorinert from 3M) and hexafluoropropylene oxide (HFPO) oligomers known as Krytox +... 

Oxidative addition of elemental fluorine to appropriate 1,3-dicarbonyl compounds provides a convenient synthesis of perfluorinated 1,2-dioxolanes. In this way (20) may be formed from difluoromalonyl fluoride, F2C(COF)2 <92JST(274)163>, and (39) is similarly prepared from either hexafluoroacetylacetone or the copper(II) or nickel(II) chelate of trifluoroacetylacetone with concomitant replacement of all remaining hydrogen atoms by fluorine <65JOCI429>. 

Sulfur tetrafluoride and F2 gas are among other fluorinating agents used for the synthesis of fluorinated ethers. For example, F-oxane was reported to form in the reaction of anhydride of F-glutaric acid or F-glutaryl fluoride with excess of SF4. Perfluorinated spiro-ethers 19 were prepared in high yield by exhaustive fluorination of the parent hydrocarbons using elemental fluorine. 

Elemental Iron (Fe(0)) is used as a reductant for remediation of namral water halocarbon contamination (reduction potential Fe(0) —0.447 V). PFOS and PFOA have been decomposed with Fe(0). To accelerate the reaction, the process can be carried out under subcritical water condition. The degradation of PFOA and PFOS has been monitored under such conditions within an argon atmosphere (T 350°C, pressure 200 atm.). In this extreme environment, PFOS degraded with a half-life of 45 min and with a fluoride yield of 55% after 6 h [53]. The hydrated electron is a very strong reductant. Compared to most other reactants (e.g., SO/") it reacts relatively fast with perfluorinated carboxylic acids (CF3COO", C3F7COO" and CyFisCOO A = 10 s" [54],)t < 2.6 x 10 M s [55]). Besides pulse... 

---