Ethers perfluoroalkyl

The relatively mild synthetic conditions during iterative growth of poly(benzyl ether) dendrons are tolerated by many peripheral groups (e.g. cyano, bromide functionality, alkyl ester, alkyl ether, perfluoroalkyl ether, oligo(ethylene glycol)... 

ECF is successfully used on a commercial scale to produce certain perfluoroacyl fluorides, perfluoroalkylsulfonyl fluorides, perfluoroalkyl ethers, and perfluoroalkylamines. The perfluoroacyl fluorides and perfluoroalkylsulfonyl fluorides can be hydrolyzed to form the corresponding acid and acid derivatives. Examples include perfluorooctanoyl fluoride [335-66-0] perfluorooctanoic acid [335-67-1] perfluorooctanesulfonyl fluoride [307-35-7] perfluorooctanesulfonic acid [763-23-1] and tris(perfluoro- -butyl)amine [311-89-7]. 

Solutions of fluorosihcones impart oil and water repeUent finishes to nylon—cotton fabrics. One series of C-1 through C-9 perfluoroalkyl substituents with varying stmctures were attached to siHcon through amide or ether linkages. The fluorosihcones having perfluorinated straight-chain... 

Synthetic oils have been classified by ASTM into synthetic hydrocarbons, organic esters, others, and blends. Synthetic oils may contain the following compounds diaLkylben2enes, poly(a-olefins) polyisobutylene, cycloaUphatics, dibasic acid esters, polyol esters, phosphate esters, siUcate esters, polyglycols, polyphenyl ethers, siUcones, chlorofluorocarbon polymers, and perfluoroalkyl polyethers. 

Alkylated aromatic lubricants, phosphate esters, polyglycols, chlorotrifluoroethylene, siUcones, and siUcates are among other synthetics that came into production during much that same period (28,29). Polyphenyl ethers and perfluoroalkyl polyethers have followed as fluids with distinctive high temperature stabiUty. Although a range of these synthetic fluids find appHcations which employ their unique individual characteristics, total production of synthetics represent only on the order of 2% of the lubricant market. Poly(a-olefin)s, esters, polyglycols, and polybutenes represent the types of primary commercial interest. 

Perfluoroalkyl ether greases thickened with polytetrafluoroethylene (MIL-G-38220 and MIL-G-27617) are used from —40 to 200°C in missiles, aircraft, and appHcations where fuel, oil, and Hquid oxygen resistance is needed (55). Polyphenyl ether greases find special use from 10 to 315°C in high vacuum diffusion pumps and for radiation resistance. 

PFA Tetrafluoroethylene-perfluoroalkyl (usually propyl) vinyl ether copolymers ... 

FITS reagents), has undergone considerable development recently [141,142,143, 144, 14S. These compounds, available fromperfluoroalkyhodides (equation 76), are very effective electrophilicperfluoroalkylating agents They react with carban-lons, aromatic compounds, alkenes, alkynes, silyl enol ethers, and other nucleophiles under mild conditions to introduce the perfluoroalkyl moiety mto organic substrates (equation 77) (see the section on alkylation, page 446). 

Perfluoroalkyl Amines, Ethers, and Carboxylic Acid Derivatives / 201... 

PERFLUOROALKYL AMINES, ETHERS, AND CARBOXYLIC ACID DERIVATIVES... 

Nucleophilic Perfluoroalkylation of Nitrones The reaction of a,N-diaryl nitrones with (trifluoromethyl)trimethylsilane (TMSCF3) gives O-trimethylsilyl ethers of a-(trifluoromethyl)-hydroxylamines. This reaction is initiated by potassium ten -butoxide. Removal of the trimethylsilyl group on acid treatment leads to a-(trifluoromethyl)hydroxylamines, whereas catalytic hydrogenation gives a-(trifluoromethyl)amines (Scheme 2.194). 

Another spacer which was used to insulate the phosphorus atom from the electron-withdrawing effect of the perfluoroalkyl tail is the -0-(CH2) - spacer that contains an electron-donating oxygen atom directly attached to the aryl ring [25]. Fluorous derivatives of triphenylphosphine containing this ether spacer (13a-c) were prepared, though the lower coupling constant of cis-... 

In contrast to the direct reduction as described above, the indirect electrochemical reduction of perfluoroalkyl halides is a versatile and novel method for generating perfluoroalkyl radicals selectively. Saveant et al. have demonstrated many successful examples. Using terephthalonitrile as a mediator, the indirect reduction of CF3Br in the presence of styrene leads to the dimer of the radical adduct obtained by the attack of CF on styrene. On the other hand, in the presence of butyl vinyl ether, the mediator reacts with the radical adduct obtained by the attack of CF3. on the olefin (Scheme 3.4) [14]. 

In a comparison of 5 and 6 (see Table 1 1.1), the existence of a perfluoroalkyl ether linkage seems to play an important role in further reducing the DE values. Teflon AF and 6 both have low dielectric constants and contain ether linkages. Since the dielectric constant of Teflon AF is lower than that of Teflon, which has a higher fluorine content, it appears that the ether linkage has an effect in lowering the DE. The Teflon AF has been reported by Resnick7 as the lowest dielectric constant (189-1.93) of any polymer thus far. 

Scheme 12 Perfluoroalkylation of ketones via germyl enol ethers...

Germyl enol ethers react with perfluoroalkyl iodides under Et3B initiation to give a-pcrfluoroalkyl ketones. The intermediate radical adduct decomposes readily via /1-elimination and provides the a-perfluoroalkyl ketone and a trialkylgermanyl radical as a chain carrier (Scheme 12) [32]. 

Silyl enol ethers have also been used as a trap for electrophilic radicals derived from a-haloesters [36] or perfluoroalkyl iodides [32]. They afford the a-alkylated ketones after acidic treatment of the intermediate silyl enol ethers (Scheme 19, Eq. 19a). Similarly, silyl ketene acetals are converted into o -pcriluoroalkyl esters upon treatment with per fluoro alkyl iodides [32, 47]. The Et3B/02-mediated diastereoselective trifluoromethylation [48,49] (Eq. 19b) and (ethoxycarbonyl)difluoromethylation [50,51] of lithium eno-lates derived from N-acyloxazolidinones have also been achieved. More recently, Mikami [52] succeeded in the trifluoromethylation of ketone enolates... 

Scheme 19 Perfluoroalkylation of silyl end ethers and lithium enolates via iodine atom transfer...

WITTIG OLEFINATION OF PERFLUOROALKYL CARBOXYLIC ESTERS SYNTHESIS OF 1,1,1-TRIFLUORO-2-ETHOXY-5-PHENYLPENT-2-ENE AND 1-PERFLUOROALKYL EPOXY ETHERS 1,1,1-TRIFLUORO-2-ETHOXY-2.3-EPOXY-5-PHENYLPENTANE (Oxirane, 2-ethoxy-3-(2-phenylethyl)-2-(trifluoromethyl)-, cis-(+)-)... 

Recently 1-perfluoroalkyl epoxy ethers have been useful starting synthons for the preparation of various perfluoroalkylated organic compounds. For example, in the... 

Plots of D versus water volume fraction " show that the concentration dependence of D is in fact described well by the Fujita free volume equation. " This was surprising considering that the underpinning of this equation simply involves available free volume for molecular hopping. The interpretation is that water molecules plasticize the perfluoroalkyl ether side chain domains and this increases D with increasing water content. D for water varied from... 

The polyimide-perfluoroalkyl ether block copolymers were prepared through the poly(amic alkyl ester) route, where a solution of diester diacyl chloride of PMDA was added to a mixture of ODA and the perfluoroalkyl ether oH-gomer, analogous to the procedure previously described [55]. Toluene was used as a cosolvent together with NMP to improve the solubility of the fluorinated coblock, and the resulting polymers were isolated by precipitation. The charac-... 

Fig. 5. Dynamic mechanical spectrum of imide-perfluoroalkyl ether block copolymer 4a.

Harrad S, de Wit CA, Abdallah MAE, Bergh C, Bjorklund JA, Covad A, Damerud PO, de Boer J, Diamond M, Huber S, Leonards P, Mandalakis M, Oestman C, Haug LS, Thomsen C, Webster TF (2010) Indoor contamination with hexabromocyclododecanes, polybrominated diphenyl ethers, and perfluoroalkyl compounds an important exposure pathway for people Environ Sci Technol 44 3221-3231... 

Solvated perfluoroalkyl zinc reagents have been prepared by reaction of perfluoroalkyl iodides with zinc in ethereal solvents such as dioxane [36,37]. Self-coupled and cross-coupled products can be formed when a mixture of acetic anhydride and methylene chloride was used [38-40] (Scheme 11). 

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