Partially fluorinated synthesis

CoF is used for the replacement of hydrogen with fluorine in halocarbons (5) for fluorination of xylylalkanes, used in vapor-phase soldering fluxes (6) formation of dibutyl decalins (7) fluorination of alkynes (8) synthesis of unsaturated or partially fluorinated compounds (9—11) and conversion of aromatic compounds to perfluorocycHc compounds (see Fluorine compounds, organic). CoF rarely causes polymerization of hydrocarbons. CoF is also used for the conversion of metal oxides to higher valency metal fluorides, eg, in the assay of uranium ore (12). It is also used in the manufacture of nitrogen fluoride, NF, from ammonia (13). 

In 1954 the surface fluorination of polyethylene sheets by using a soHd CO2 cooled heat sink was patented (44). Later patents covered the fluorination of PVC (45) and polyethylene bottles (46). Studies of surface fluorination of polymer films have been reported (47). The fluorination of polyethylene powder was described (48) as a fiery intense reaction, which was finally controlled by dilution with an inert gas at reduced pressures. Direct fluorination of polymers was achieved in 1970 (8,49). More recently, surface fluorinations of poly(vinyl fluoride), polycarbonates, polystyrene, and poly(methyl methacrylate), and the surface fluorination of containers have been described (50,51). Partially fluorinated poly(ethylene terephthalate) and polyamides such as nylon have excellent soil release properties as well as high wettabiUty (52,53). The most advanced direct fluorination technology in the area of single-compound synthesis and synthesis of high performance fluids is currently practiced by 3M Co. of St. Paul, Minnesota, and by Exfluor Research Corp. of Austin, Texas. 

The reaction of tetramethylsilane with fluorine led to the isolation of several, partially fluorine-substituted tetramethylsilanes (see Tables VII-IX), and preservation of over 80% of the silicon-carbon bonds in the initial, tetramethylsilane reactant. The stability of many of the partially fluorinated germanes and silanes (some are stable to over 100°C) is very surprising, for the possibility of elimination of hydrogen fluoride is obvious. Indeed, before the first reported synthesis (12) of... 

As mentioned in the introduction, partially fluorinated compounds are highly useful, however methods for their synthesis are strictly limited in many cases. For example, nucleophilic substitution occurs with difficulty at the position a to a trifluoromethyl group due to its strong electron-withdrawing effect, although sulfur and selenium nucleophiles undergo such a substitution rather efficiently (Scheme 6.1). 

Wholly aromatic polymers are thought to be one of the more promising routes to high performance PEMs because of their availability, processability, wide variety of chemical compositions, and anticipated stability in the fuel cell environment. Specifically, poly(arylene ether) materials such as poly-(arylene ether ether ketone) (PEEK), poly(arylene ether sulfone), and their derivatives are the focus of many investigations, and the synthesis of these materials has been widely reported.This family of copolymers is attractive for use in PEMs because of their well-known oxidative and hydrolytic stability under harsh conditions and because many different chemical structures, including partially fluorinated materials, are possible, as shown in Figure 8. Introduction of active proton exchange sites to poly-(arylene ether) s has been accomplished by both a polymer postmodification approach and direct co-... 

Synthesis and Properties of Partially Fluorinated Polyimides for Optical Applications... 

This chapter describes the synthesis of partially fluorinated polyimides for optical teleconununications applications," " 2 their optical transparency (optical loss), refractive index, and birefringence properties" in addition to their fundamental properties. It also describes their device application as optical interference filters," " optical waveplates," and optical waveguides." -" ... 

All other fluorinated antibiotics were either prepared by a partial chemical synthesis or by cultivations to which fluorine ions were added. All metabolites prepared in this way and initially considered very promising with respect to their increased biological activity were an absolute failure, in spite of the fact that just the contrary was often described in the patent literature. 

Erian, A.W., Konno, A., and Euchigami, T., Electrolytic partial fluorination of organic compounds. Part 19. A novel synthesis of fluorothieno[2,3-h]pyridines using anodic fluorination of heterocyclic sulfides as a key step, J. Org. Chem., 60, 7654, 1995. 

Scheme 2.44 Nucleophilic replacement of fluorine in only partially fluorinated systems is an important tool for synthesis of pharmaceuticals, for example (S)-norfluoxetine, a serotonin re-absorption inhibitor [100].

As early as the 1940s Emeleus and Haszeldine [17] discovered that perfluoroalkyl iodides are not only cleaved into perfluoroalkyl radicals by light but also that they add readily to a variety of olefins to yield telomers and 1 1 adducts [18]. This kind of radical chain reaction can also be initiated by high temperatures (Scheme 2.100). The addition of perfluoroalkyl iodides to olefins is a very important method for synthesis of partially fluorinated alkanes, polymers, oligomers, and their derivatives [19]. The synthesis of some perfluoroalkyl aromatic compounds can also be achieved [20]. 

If equimolar quantities of tetramethylammonium fluoride and a threefold excess of Me3SiCF3 or its homologues are used the perfluoroalkyltrimethyl silane acts as an effective source of nucleophilic perfluoroalkyl equivalents for nucleophilic substitution of aliphatic triflates [90] (Scheme 2.136). This method enables the simple synthesis of partially fluorinated alkane structures which are of interest in the chemistry of liquid crystals and other functional materials. 

Eheparations for seleninyl fluoride and selenium tetrafluoride that require only Se02 and SP4 are very convenient and are identical to that used for the synthesis of Tep4. Other methods of preparation include partial fluorination of elemental... 

Modification of this reaction by the addition of hydrocarbon olefin has been found to be a general preparative method for synthesis of partially fluorinated tetrahy-drothiophenes. " ... 

As mentioned in the Introduction, partially fluorinated compounds are highly useful. However, methods for their synthesis are strictly... 

Synthesis of partially fluorinated heterocycles from 4,4-bis(trifluoro-methyl)-substituted hetero-1,3-dienes via C—F bond activation and their application as trifluoromethyl-substituted building blocks 06H (69)569. 

A bisphenol monomer, 2,2 -dimethylaminemethy-lene-4,4 -biphenol has been prepared by the Mannich reaction of dimethylamine and formaldehyde with 4,4 -biphenol. This monomer can be used for the synthesis of partially fluorinated PAES polymers with pendant quaternary anunonium groups. The synthesis is shown in Figure 7.2. 

Lee HS, Roy A, Lane O, Lee M, McGrath JE. Synthesis and characterization of multiblock copolymers based on hydrophilic disulfonated poly(arylene ether sulfone) and hydrophobic partially fluorinated poly(arylene ether ketone) for fuel cell applications. J Polym Sci Part A Polym Chem 2010 48(l) 214-22. 

There are three methods for the introduction of fluorine atoms into the solvent molecules, which are common organic chemical synthesis, electrolytic fluorination, and direct fluorination using elemental fluorine (F2 gas), respectively. The direct fluorination is the simplest method to prepare partially fluorinated organic solvents. It makes possible to obtain many interesting fluorinated organic solvents. Among the important solvents for practical lithium batteries, the direct fluorination has already been applied to propylene carbonate (PC) [6] and 1,2-dimethoxyethane (DME) [7] in the late 1960s. 

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