Alkyl fluoroalkyl ethers

Aldrich PE, Sheppard WA (1964) a-Ruorinated ethers. II. Alkyl fluoroalkyl ethers. J Org Chem 29 11-15. doi 10.1021/jo01024a002... 

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. 

During the year 1970, several articles were published by Kim et al. [41-46] about the synthesis and the properties of fluorinated hybrid silicone homopolymers and copolymers. These polymers were obtained by hydrosilylation of a, (D-dienes with chlorohydrogenosilanes, and the obtained bis-chlorosilanes were then hydrolysed into bis-silanols and polymerized or copolycondensed (R = R or R or R or R, Z = alkyl, aUcyl ether, fluoroalkyl, fluoroether, etc.) (cf. Scheme 19). 

All the homopolymers or copolymers that have been obtained show very interesting properties in terms of thermal stabiUty. They generally present rather low TgS and good stability at high temperature and may thus be used over a wide range of temperature. Fmthermore, in the search for new materials for new applications, the obtention of polymers with specific properties is required, and depending on the nature of their main chain (alkyl, fluoroalkyl, aryl, fluoroaryl, aUcyl ether, etc.) and on the nature of their side chains, these hybrid silicones may be directed to exhibit specific properties. 

A survey of a variety of polymerizable groups indicated that in the preferred free-radical aqueous-emulsion polymerization system, a per-fluorovinyl ether most nearly fulfills these requirements. In general, the perfluorovinyl ethers copolymerize at a reasonable rate. They change little in rate with variations in chain length or functionality in the per-fluoroalkyl moiety so long as the type of functionality on the perfluoro-alkyl group is consistent with requirements (a) and (b). In addition, such ethers furnish thermally resistant structures in the polymer. 

The synthesis of fluoroalkyl and chlorofluoroalkyl ethers occurs readily by base-catalyzed nucleophilic addition of alcohols to haloalkenes. An example is the s3mthesis of the alkyl 2,2-dichloro-l,l-difluoroethyl ethers, where R is methyl or 1° or 2° alkyl (equation 9.80). Nucleophilic addition can also occur with alkynes that are activated by the presence of groups such as trifluoromethyl. An example is the addition of methoxide to hexafluoro-2-but)me (87) to produce the methoxy ether with trans trifluoromethyl groups (88, equation 9.81). Note that the orientation of addition to the alkyne is anti, a pattern that is frequently— but not always—observed. ... 

Scheme 2.52 Structure of sulfonated poly(arylene ether sulfone) ionomers with three different types of acidic groups (fluoroalkyl sulfonic, aryl sulfonic, and alkyl sulfonic acids). Taken from Ref. [185].

In contrast to the well-known alkylation paths, namely, S l and Sn2, the fluoroalkylation reaction was rationalized by an unusual ionic chain mechanism [26]. As shown in Scheme 14.3, the reaction was initiated with the direct attack of electron-positive bromine (5+) on the BrCF2CF2Br by phenoxide. Tetrafluoroethy-lene (CF2=CF2) was generated in situ after loss of bromide anions. The phenoxides added to the CF2=CF2 to give the reactive fluorocarbanions, which were quickly terminated by bromide to form 2-bromo-tetrafluoroethyl aryl ethers. In the elimination step, zinc inserted into the C—Br bond of 2-bromo-tetrafluorethyl aryl ethers in a similar way to the preparation of Grignard reagents. Finally, the aryl trifluorovinyl ethers were obtained by the elimination of ZnBrF salt at elevated temperature. 

Shavnya A, Sakya SM, Munich ML, Rast B, DeMello KL, Jaynes BH (2005) Efficient fluoride-mediated synthesis of 5-alkyl amino- euid ether-substituted pyrazoles. Tetrahedron Lett 46 6887-6891. For the regioselective synthesis of 1-alkyl-5-fluoroalkyl-3-hydroxypyrazoles, see Hamper BC, Kurtzweil ML, Beck JP (1992) Cyclocondensation of alkylhydrazines and p-substituted acetylenic esters Synthesis of 3-hydroxypyrazoles. J Org Chem 57 5680-5686... 

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