Fluoroalkyl ether

Applications. Table 12 Hsts crop-protection chemicals and pharmaceuticals containing the aryl fluoroaLkyl ether group. 

Diethylaminosulfur trifluoride (DAST) reacts with epoxides to give com plex mixtures in which vicinal as difluorides, gemmal difluorides, and bis(2-fluoroalkyl) ethers are the mam components I6 (equations 16 and 17)... 

A fluorine-hydrogen migration is typical for the reactions of aldehydes branched at the carbon atom a to the formyl group. Comparable amounts of 1,1 -difluoroalkanes and 1,2-difluoroalkanes together with bis(l -fluoroalkyl) ethers are obtained [169] (equation 84). 

Aliphatic carboxylic acids react with sulfur tetrafluonde to give, in addition to 1,1,1-trifluoromethylalkanes, considerable amounts of symmetrical bis(l,l-di-fluoroalkyl)ethers. Yields of the ethers are related to the nature of the acids and to the reaction conditions. The optimum conditions for the formation of the ethers depend on their stability in highly acidic reaction medium and on the reactivity of the acids toward sulfur tetrafluonde Simple unsubstituted acids form the ethers only at low temperatures, whereas longer chain and cycloaliphatic acids give the corresponding ethers at somewhat higher temperatures Halosubstituted acids form the ethers at the relatively high reaction temperatures necessary for these reactions to proceed [203, 204, 205] (equation 101). 

The high thermal and chemical stability of fluorocarbons, combined with their very weak intermolecular interactions, makes them ideal stationary phases for the separation of a wide variety of organic compounds, including both hydrocarbons and fluorine-containing molecules Fluonnated stationary phases include per-fluoroalkanes, fluorocarbon surfactants, poly(chlorotrifluoroethylene), polyfper-fluoroalkyl) ethers, and other functionalized perfluoro compounds The applications of fluonnated compounds as stationary phases in gas-liquid chroma... 

A higher level of incorporation can be achieved by resubjecting the modified polymer to the reaction conditions, as seen in the conversion of sample 6 -> 7. A third exposure to the conditions, which involved the conversion of sample 7 -> 8, does not give higher incorporation, and in fact appears to result in a decrease. Thus the reaction appears to be self-limiting, and the existing fluoroalkanol or fluoroalkyl ether groups may act to quench the radical promoter, and inhibit further incorporation. 

To aid in the characterization of the modified polymer samp os 1-10, and of the mixtures 11 and 12 obtained from functionalizing the two cycloalkanes, we prepared the model fluoroalkanols 13 and 14 as shown in Equation 2 (11-12), and the model fluoroalkyl ethers 15 and 16 as shown in Equation 3 1 3). Compounds 13 and 15 were previously isolated by- the Dupont group (8) from their mixture 11. Products 13-16 proved to be good comparison compounds for the infrared spectra, and particularly- for the 19F-NMR spectra. The I9F-NMR signal for the fluoroalkanol is approximately 1 ppm downfield from that of the fluo-roalky.l ether, which is enough to get semiquantitative ratios of... 

Treatment of epoxides with DAST results in the formation ofgem-difluorides, vicinal difluorides and bis(2-fluoroalkyl) ethers.54 The product distribution is dependent upon the nature of the epoxide. For example, cyclohexene oxide (1) gives a mixture of eis-difluorides and bis(a-fluoro) ethers, whilst styrene oxide (2) affords a mixture of difluorophenylethanes. This reaction is of little practical use due to the problems associated with the isolation of pure products. 

Vicinal fluoroalkyl ethers are also obtained from olefins and methyl hypo-fluorite at low temperatures [168] and from the unstable reagents generated from additions of xenon difluoride to methanol [169] or other alcohols [170] Alcohols tend to give complex product mixtures depending on the olefin structure, and best results are often achieved when reactions are run in the presence of boron tri-fluonde Additions of xenon difluoride to trifluoromcthanesulfomc fluorosulfonic, or nitric acids give fluoroxenonium reagents that are stable to about -10 °C and... 

Aryl fluoroalkyl ethers have been prepared from the reaction, at room temperature in HMPA, of fluo-ro-substituted alkoxides with activated fluoro-,149 nitro-,149 and, at 150 °C, also chloro-arenes150,151 and some chloro-substituted pyrazines (equation 15), pyrimidines, quinolines,150,152 and pyridines.152 Disubstitution was observed in die presence of comparably activated leaving groups such as in 2,4- and 2,6-di-chloronitro- or cyano-benzenes, whereas regiospecific substitution took place at position 4 in 3,4-dichloronitro- or cyano-benzene and at position 2 in 2-fluoro-6-chlorocyanobenzene.151 Steric hindrance and the number of fluorine substituents in the alkoxide pose limits to the reactivity. Thus, tertiary alkoxides, or alkoxides containing more than four fluorine substituents, displace activated nitro and fluoro, but not chloro substituents.149,150 The secondary hexafluoro-2-propoxide anion does not react even with the more reactive nitro and fluoro derivatives.149... 

Kim J, Singh R P, Shreeve J M. Ixiw melting inorganic salts of alkyl-, fluoroalkyl-, alkyl ether-, and fluoroalkyl ether-substimted oxazohdine and morpholine. Inorg. Chem. 2004. 43, 2960-2966. 

The corresponding fluoroalkyl ethers 119 (cf. Scheme 27) have been prepared by the reaction of fluoroalkyl alcohols with dihydroartemisinin 115 using various methods (with BF3-Et20 or TMSCl as catalysts) in moderate to good yields <1998JME4101>. 

Organic compounds that contain C-F bonds generally show nonflammability or fire-retardant property. Thus, fluoroalkyl-ethers and -esters have been attempted as nonflammable or flame-retardant solvents for LIB electrolytes [88, 89,113]. Fluorinated alkylphosphates, or fluoroalkylphosphates, have higher flame-retardant properties than the corresponding alkylphosphates. Jow and co-workers [104, 114-116] reported a series of fluoroalkylphosphate, i.e., tris(2,2,2-trifluoroethyl) phosphate (TEP), bis(2,2,2-trifluoroethyl)-methyl phosphate (BMP) and (2,2,2-trifluoroethyl)-diethyl phosphate (TDP) (Fig. 2.24), as nonflammable additives or co-solvents of... 

Triflyl chloride was also used for the preparation of fluoroalkyl trifluoromethanesulfonates that act as highly efficient fluoroalky-lating reagents, 10 times more reactive than the corresponding tosylates. Significant formation of fluoroalkyl ether side-products was observed when trifluoromethanesulfonyl fluoride was used. Fluoroalkyl p-nitrophenyl ethers were thus prepared in high yields, without side-elimination reactions (eq 7). ... 

Sheppard WA (1964) a-Fluorinated ethers. I. Aryl fluoroalkyl ethers. J Org Chem 29 1-11. doi 10.1021/jo01024a001... 

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