Alkyl-substituted perfluorinated

During electrochemical fluorination retention of important functional groups or atoms in molecules is essential. Acyl fluorides and chlorides, but not carboxylic acids and anhydrides (which decarboxylate), survive perfluorination to the perfluorinated acid fluorides, albeit with some cyclization in longer chain (>C4) species [73]. Electrochemical fluorination of acetyl fluoride produces perfluoro-acetyl fluoride in 36-45% yields [85]. Electrochemical fluorination of octanoyl chloride results in perfluorinated cyclic ethers as well as perfluorinated octanoyl fluonde. Cyclization decreases as initial substrate concentration increases and has been linked to hydrogen-bonded onium polycations [73]. Cyclization is a common phenomenon involving longer (>C4) and branched chains. a-Alkyl-substituted carboxylic acid chlorides, fluorides, and methyl esters produce both the perfluorinated cyclic five- and six-membered ring ethers as well as the perfluorinated acid... 

A summary of metathesis reactions in ionic liquids is presented in Table 7.1. From the data available it appears that these reactions can easily be performed in neat ionic liquids and increased reaction rates are sometimes observed relative to molecular solvents. Co-solvents are used in some cases, mainly to obtain a biphasic system and thereby facilitate product isolation. So far, only imidazolium-type solvents have been employed with variations in the alkyl substitution pattern and the nature of the anion. Apart from the common perfluorinated anions, chloroaluminates have also been used,... 

This route is especially valuable for the transformation of electron-rich heteroaromatic compounds into their fluorinated analogues, which are not suitable for the nucleophilic exchange route. The method has been extended by addition of fluorinated olefins. The fluoroolefins add in a radical process to the 2-position of tetrahydrofuran, followed by perfluori-nation to give the perfluorinated 2-alkyl-substituted tetrahydrofurans in excellent yields [84JFC(25)523 85JFC(29)323] (Scheme 3). 

Arnone et al. studied the epoxidation of various olefins 220 with perfluorinated oxaziridine 80 (Equation 10) <1996JOC8805>. Alkyl-substituted olefins are epoxidized with this oxaziridine under particularly mild conditions. Electron-deficient substrates can also be epoxidized, and the more electron deficient the double bond is, the more severe the reaction conditions become. The reaction is chemoselective and stereoselective, with air-alkenes affording air-epoxides. Various complex and polyfunctionalized substrates of natural origin (monoterpenes, sesquiterpenes, and steroids) have been epoxidized effectively with this reagent (Table 18). 

Hydrolysis of alkyl-substituted phosphine oxides is generally difficult, heating with solid sodium or potassium hydroxide is needed in order to break the P—C bond. Hydrolysis of phosphonates and phos-phinates occurs with P—O cleavage in preference to P—C cleavage. Exceptions have been reported with several aromatic phosphine oxides containing p- and o-nitrobenzyl groups and other stabilized systems. Perfluorinated phosphine oxides can also be hydrolyzed to the phosphinic and phosphonic acids.2 ... 

Percec et al. described the self-assembly of Rp-substituted bis-dendritic benzamides, such as compounds 179a and 179b, combining a dendron decorated with perfluorinated chains and a dendron with alkyl chains. In the hexagonal columnar LC phases of these molecules the smaller alkyl chains form the centers of the columns, the aromatics are arranged in cylindrical shells surrounding the aliphatic columns, while the larger fluorinated chains form a fluorous continuum... 

Perfluorinated alkyl radicals, generated by photoinduction from heptadecafluoro-octyl iodide, were added to SWCNTs and the perfluorooctyl-derivatized CNTs obtained (Scheme 1.14). No difference in the solubility of the fluoroalkyl-substituted nanotubes and the starting materials was observed [148]. A pathway to the radical functionalization of CNTs sidewalls was predicted by classical molecular dy-... 

Syntheses of heterocyclic compounds with perfluorinated side chains are mainly performed by substitutional fluorinations of the available fragments or by the introduction of a perfluoroalkyl group in the heterocycle. The development of convenient approaches and direct perfluoro-alkylation methods is a current challenge. 

Dendrons attached as side chains on linear polymer chains behave different from free dendrimers and dendrons. Block copolymers, poly(3,5-bis(3,5-bis (benzyloxy)benzyloxy)-benzyl methacrylate-random-methacrylic acid)-block-poly(2-perfluorooctylethyl acrylate), possess poly(benzylether) dendrons and perfluorinated alkyl chains in their side chains (Fig. 4) [85], While an LB film of a copolymer with a medium substitution fraction of poly(benzylether) dendron side chain in poly(methacrylic acid) displays flat surface, a copolymer with high fraction of poly(benzylether) dendron side chains produces the zone texture. Dendron rich blocks are hydrophobic and oleophilic but perfluorinated blocks are solvophobic. Therefore, in this case, the solvophobicity-to-solvophilicity balance must be considered. As a result, copolymers with medium fraction of dendron are laid on solid substrate, but dendron blocks of copolymers with high fraction prefer to arrange at air side of air/ water interface and the fluorocarbon blocks are enforced to exist close to water subphase, resulting in the zone texture [86]. These situations of molecular arrangements at air/water interface are kept even after transfer on solid substrate. By contrast, when perfluorooctadecanoic acids are mixed with block copolymers with high dendron fraction, the flat monolayers are visualized as terrace [87], The monolayers are hierarchized into carboxyl, per-fluoroalkyl, and dendron layers, that is, hydrophilic, solvophobic, and oleophilic layers. In this case, perfluorooctadecanoic acids play a role for ordering of block copolymers. 

Perfluorinated alkyl iodide.s arc very important intermediates for the synthe.sis of perfluoroalkyl-substituted compounds. They can be prepared by addition of fluorine and iodine to fluorinated alkenes. This addition can be carried out with various sources of "IF" fluorine/iodine, hydrogen fluoridc/iodine, - - potassium fluoride/iodine, - - iodine pentafluoride/iodine. "-" """ - " - -" " " " " or iodine trifluoridc/ iodine. - ... 

Surfactants used in the polymerization are water-soluble, halogenated surfactants. They are in particular fluorinated surfactant such as ammonium, substituted ammonium, quarternary ammonium, or alkali metal salts of perfluorinated or partially fluorinated alkyl carboxylates, monoalkyl phosphate esters, alkyl ether or polyether carboxylates, alkyl sulfonates, and alkyl sulfates. 

Other similar methods which involve cyclization of iV-substituted diaminoalkenes or -alkanes include the preparation of 2-alkyl- and 2-acyl-l-methylimidazole-4-carboxylates from methyl (Z)-j -dimethylamino-a-isocyanoacrylate (191) in reaction with an alkyl or acyl halide <82LA2093>, the preparation of perfluorinated 3-imidazolines (192) <83S169>, the high yield synthesis of 2-imidazolines by decay of phosphaza compounds (193) in a version of the intramolecular Staudinger reaction <85T793>, and the formation of 1,3-diaroylimidazolidines (34-71%) when bis-alkylidene-or -arylidene-ethylenediamines react with acid chlorides in polar solvents (Scheme 129)... 

In the recent literature numerous reactions in which enamines are used for synthesis of enantiomerically pure compounds (EPC) can be found . Optically active enamines from substituted pyrrolidine (e.g. 27, R = CH20Me, CH20SiMe3, or 28, R = Me, CH20Me), or from piperidine , such as 29, (S)-phenylethylamine (30) " and stanna-N,0-heterocyclic amine (31) , are used. The cyclohexanenamines seem to be the preferred test compounds for this kind of reaction, whereas enamines of open-chain ketones and aldehydes have been investigated only rarely . Enamines from carbonyl compounds and secondary amines are obtained with azeotropic removal of water or by die Weingarten method with TiC. A titanium chloride-catalysed variation in which perfluorinated alkyl groups can be introduced is also known " . 

Scheme 4.7-6 Rhodium-catalyzed hydroformylation in SCCO2 [11]. The notation used here and in the text defines perfluorinated alkyl substituents of general formula (CH2)y(CF2)zF with the x giving the substitution position relative to phosphorus [22]. TPP and TPOP are used as acronyms for triphenylphosphine and triphenylphosphite, respectively. 1) pical results are listed in Table 4.7-3 and represented in Figure 4.7-5.

A large number of perfluorinated heterocyclic compounds was prepared (mostly using ECF technology) in 1970-1990 during the quest for the best materials to be used as oxygen carriers in perfluorocarbon emulsions, so-called blood substitutes (for detailed review on this effort, see Ref. 34). The list of synthesized materials includes perfluorinated A-alkyl(cycloalkyl) pyrrolidines, oxazolidines, piperidines and... 

A new class of compounds known as lithium fluoroalkylphosphates was introduced [87-89]. The premise for their development was that the substitution of one or more fluorine atoms in LiPFe with electron-withdrawing perfluorinated alkyl groups should stabilize the P-F bond, rendering it stable against hydrolysis and resulting in an improved thermal stability of the salt. The hydrophobic perfluorinated alkyl groups sterically shield phosphorus against hydrolysis. The new compounds also have conductivity comparable... 

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