Perfluorohexylation

FLUORINECOMPOUNDS,ORGANIC - FLUORINATED HIGHERCARBOXYLIC ACIDS] (Volll) Perfluorohexyl ether [424-20-4]... 

FLUORINECOMPOUNDS,ORGANIC - FLUOROETHERS AND FLUORO AMINES] (Vol 11) Perfluorohexyl iodide [355-43-1]... 

Preparation of 2-(Peifluorohexyl)cyclohexanone from Perfluorohexyl Iodide 143]... 

N-Cyclohex-l-enylpyrrolidine (9 g 0 06 mol) was dissolved in pentane with A -ethyldiisopropylamine (7.8 g 0.06 mol). Perfluorohexyl iodide (13.4 g, 0.03 mol) IS added to the solution. Aprecipitate of A-ethyldiisopropylamine hydroiodide IS formed instantly After 3 h, the precipitate is filtered off, and the solution is evaporated The crude liquid is hydrolyzed with 6 mL of 40% sulfuric acid The mixture is stirred for 3 h and extracted with ether. The ether layer is neutralized with aqueous sodium hydrogen carbonate, washed with water, and dried over magnesium sulfate. The solvent is evaporated, and the residue is distilled. A second distillation with a spinning-band column yields 7 9 g (63%) of pure 2-(perfluoro-hexyl)cyclohexanone (bp, 71 -73 °C at 0 4 mm of Hg). 

Preparation of N-Butyl Perfluorohexylimidoyl Iodide from Perfluorohexyl Iodide [Ml]... 

In a similar reaction, iodine fluonde also can be removed from perfluorobutyl-, perfluorohexyl-, and perfluorooctyl iodide by using zinc-copper couple in dimethyl sulfoxide or dimethylformamide [71]... 

We have studied the hydrogenolysis of 2-(perfluorohexyl)ethane thiocyanate to 2-(perfluorohexyl)ethane thiol. It was discovered that perfluoroalkyl thiocyanates can be reduced to thiols and co-product hydrogen cyanide with molecular hydrogen in the presence of a carbon-supported palladium-tin catalyst. This result is surprising since it is known that palladium and other gronps 8 to 10 metal catalysts are poisoned by the product thiol, traces of hydrogen snlfide byprodnct, and the hydrogen cyanide co-product. For that reason, we characterized the catalyst to understand why it was so robust under conditions that would normally poison snch a catalyst. 

Perfluoroalkyl)ethane thiols have been used as precursors to fluorinated surfactants and products for hydro- and oligophobic finishing of substrates such as textiles and leather (1). The synthesis of 2-(perfluoroalkyl)ethane thiol and a byproduct bis-(-2-perfluoroalkylethane)-disulfide (5-10%) has been practiced via the reaction of 2-(perfluoroalkyl)ethane iodide with thiourea to form an isothiuronium salt which is cleaved with alkali or high molecular weight amine as shown in Equation 1 for 2-(perfluorohexyl)ethane iodide (1). 

Nucleophihc substitution of sodium thiolate on 2-(perfluorohexyl)ethane iodide leads to extensive elimination (10-20%) and formation of (perfluorohexyl)ethylene (3), Equation 2. 

It has been known for many years that 2-(perfluorohexyl)ethane thiocyanate can be synthesized in qnantitative yields from 2-(perfluorohexyl)ethane iodide (4), as shown in Equation 3. 

Perfluorohexyl)ethane iodide was obtained from the Surface Protection Solntions business at DuPont. Sodinm thiocyanate was purchased from Aldrich and nsed without further purificatiom The 2-(perfluorohexyl)ethane iodide was converted to... 

Abbreviations Bdmpe[l,l-Bis(3,4-dimethylphenyl)ethane] Pfhethiol (2-perfluorohexyl)ethane thiol). 

D. P. Curran, S. Hadida, Tris(2-(Perfluorohexyl)tin Hybride A New Fluorous Reagent for Use in Traditional Organic Synthesis and Liquid Phase Combinatorial Synthesis , J. Am. Chem. Soc 1996,118,2531. 

D. P. Curran, S. Hadida, S. Y. Kim, Tris(2-Perfluorohexyl-ethyfltin Azide A New Reagent for Preparation of 5-Substituted Tetrazoles from Nitriles with Purification by Fluorous Organic Liquid-Liquid Extraction , Tetrahedron 1999, 55, 8997. 

Ether and benzene were distilled with sodium/benzophenone prior to use. The 2-perfluorohexyl-1-iodoethane was purchased from Lancaster and the FC-72 was purchased from 3M. Magnesium (powder, 50 mesh) and all other reagents were purchased from Aldrich Chemical Company, Inc. 

On the heels of work by Zhu and Horvath and Rabai, perfluorocarbon solvents and fluorous reagents have been used increasingly in organic syntheses. Ruorous compounds often partition preferentially into a fluorous phase in organic/fluorous liquid-liquid extraction, thus providing easy separation of the compounds. Tris[(2-perfluorohexyl)ethyl]tin hydride combines the favorable radical reaction chemistry of trialkyltin hydrides with the favorable separation features of fluorous compounds. 

Tris[(2-perfluorohexyl)ethyl]tin hydride has three perfluorinated segments with ethylene spacers and it partitions primarily (> 98%) into the fluorous phase in a liquid-liquid extraction. This feature not only facilitates the purification of the product from the tin residue but also recovers toxic tin residue for further reuse. Stoichiometric reductive radical reactions with the fluorous tin hydride 3 have been previously reported and a catalytic procedure is also well established. The reduction of adamantyl bromide in BTF (benzotrifluoride) " using 1.2 equiv of the fluorous tin hydride and a catalytic amount of azobisisobutyronitrile (AIBN) was complete in 3 hr (Scheme 1). After the simple liquid-liquid extraction, adamantane was obtained in 90% yield in the organic layer and the fluorous tin bromide was separated from the fluorous phase. The recovered fluorous tin bromide was reduced and reused to give the same results. Phenylselenides, tertiary nitro compounds, and xanthates were also successfully reduced by the fluorous fin hydride. Standard radical additions and cyclizations can also be conducted as shown by the examples in Scheme 1. Hydrostannation reactions are also possible, and these are useful in the techniques of fluorous phase switching. Carbonylations are also possible. Rate constants for the reaction of the fluorous tin hydride with primary radicals and acyl radicals have been measured it is marginally more reactive than tributlytin hydrides. ... 

A. (Perfluorohexyl)ethylmagnesium iodide. A 500-mL, three-necked flask equipped with a stirring bar etnd a reflux condenser is dried in an oven overnight and then cooled under argon. Dry ether (20 mL) and 2-perfluorohexyl-1-iodoethane (1 mL) ate added to magnesium (2.91 g, 120 mmol) in the dried flask equipped with a reflux condenser, thermometer and an outlet to argon gas (Note 1). The reaction is initiated by... 

C. Brornotris[2-(perfluorohexyl)ethyl]tin. The fluorous phenyltin product (17.2 g, 13.9 mmol) and dry ether (80 mL) are transferred to a 250-mL, three-necked flask that had been dried in an oven and cooled to 0°C under argon. Bromine (0.71 mL, 14 mmol) is added dropwise over 30 min to the mixture. The addition rate is adjusted to keep the temperature between 0° and 1°C. The mixture is warmed to 25°C and stirred for 7 hr. The reaction mixture is transferred to a 250-mL, round-bottomed flask. The ether and excess bromine are removed under reduced pressure to leave a yellow oil. The oil is dissolved in FC-72 (75 mL) and transferred to a 250-mL separatory funnel. The bromine and bromobenzene by-products are removed by washing three times with methylene chloride (3 x 75 mL) leaving the fluorous layer colorless. The FC-72 is removed under reduced pressure to provide 15.8 g (12.7 mmol, 92%) of a colorless oil (Note 6). 

Perfluoro- decalin Perfluo- rooctane Perfluorohexyl- ethane Perfluorobutyl- butane... 

All compounds used had equivalent purity (see Table 11). The test design was focused on the evaluation of histological differences after a tamponade time of 6 weeks. The density of the PFCLs used was 1.32 g/ml (perfluorobutylbutane), 1.62 g/ml (perfluorohexyl-ethane) and 1.78 g/ml (PFO). There was no dose-response relationship that means there is no evidence that a higher density creates more severe histological damage. Therefore, the simple explanation of the insufficient long-term tolerance for PFCLs could not be verified. 

Our own investigations concentrated on compounds with different densities (PFO and perfluorohexyl-ethane) and additionally on compounds with comparable densities but different viscosities. Perfluorohexyl-ethane was tested as a monomer and in two oligomeric configurations with the same molecular unit but... 

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