Synthesis fluorinated material

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-... 

The biotransformation of organofluorine materials into optically active functionalized fluo-rinated materials along with a discussion on the effect of fluorine atom(s) during enantio-selective and/or diastereoselective transformations is described. The ability of microorganisms to discriminate between enantiomers is particularly important regarding resolution and asymmetric synthesis. Furthermore, the use of chiral fluorinated materials in the design and preparation of new types of biologically active materials is discussed. 

The well known ability of antimony pentafluoride to oxidize some elements, such as sulfur or selenium, to the corresponding polynuclear cations [1] found its application in the synthesis of fluorinated materials. Reaction of sulfur with TFE, HFP, and PFIB in the presence of SbF5 was reported [ 129,130] ... 

The search for new selective synthons is an important area in organo-fluorine chemistry.1 4 In recent years organosilicon chemistry has become important in the development of new methodologies in organic synthesis.5-8 Anionic activation of tetracoordinate organosilicon species has been utilized for a variety of C —C and carbon heteroatom bond formation strategies in syntheses of highly fluorinated materials.9 13... 

The material presented in this chapter indicates that the synthesis of fluorinated heterocyclic compounds has attracted considerable attention from the viewpoint of new methods and approaches the specific features of perfluorinated organic compounds are extensively used to create new fluorinated materials with wide applications. Recent growth of fluoroorganic chemistry has led to the discovery of new fluorine-containing heterocyclic compounds with unique structures many of these compounds exhibited specific biological activity and proved to be effective drugs and pesticides. It is hoped that more original methods for the synthesis of heterocyclic... 

K Kawai, T. Ebata, T. Kitazume, The synthesis of fluorinated materials in microreactors. Journal of Fluorine Chemistry, 2005, 326, 956-961. 

Table 5.6 Horner-Wadsworth-Emmons olefination for synthesis of fluorinated material.

N. Miyake, T. Kitazume, Microreactors for the synthesis of fluorinated materials. J. Fluorine Chem. 2003, 122, 243-246. 

The book arose from discussions that took place during the FUNFLUOS project (2004—2008), carried out within the Sixth European Framework Programme. This project involved about ten groups from Germany, France, Slovenia and the UK, all aimed at the synthesis and characterization of fluorinated materials with properties tailored for specific applications. 

LC15-0133 has been reported as a dipeptidyl peptidase IV (DPP-IV) inhibitor for the potential treatment of type 2 diabetes. A key step in the synthetic sequence of the medicinal chemistry route is the fluorination of the Boc-protected pyrrolidine using 1.1-1.2 equivalents of DAST (Scheme 15.22) at 78 °C to give the desired compound in 70% yield. Upon scale-up, the team demonstrated that the reaction could be executed at 0 °C with an excess of DAST (1.9 equivalents) to provide the fluorinated material in 85% with only 5% of the corresponding elimination product. A slight exotherm was observed upon dropwise addition of the DAST on multikilogram scale, and the crude product was carried directly into the next step of the synthesis after aqueous extractive work-up. 

Pubhcations have described the use of HFPO to prepare acyl fluorides (53), fluoroketones (54), fluorinated heterocycles (55), as well as serving as a source of difluorocarbene for the synthesis of numerous cycHc and acycHc compounds (56). The isomerization of HFPO to hexafluoroacetone by hydrogen fluoride has been used as part of a one-pot synthesis of bisphenol AF (57). HFPO has been used as the starting material for the preparation of optically active perfluorinated acids (58). The nmr spectmm of HFPO is given in Reference 59. The molecular stmcture of HFPO has been deterrnined by gas-phase electron diffraction (13). 

Numerous avenues to produce these materials have been explored (128—138). The synthesis of two new fluorinated bicycHc monomers and the use of these monomers to prepare fluorinated epoxies with improved physical properties and a reduced surface energy have been reported (139,140). The monomers have been polymerized with the diglycidyl ether of bisphenol A, and the thermal and mechanical properties of the resin have been characterized. The resulting polymer was stable up to 380°C (10% weight loss by tga). 

When the fluorine used for synthesis contained traces of oxygen, the solid behaved as a powerful oxidant (causing 2-propanol to ignite on contact) and it also exploded on impact. Material prepared from oxygen-free fluorine did not show these properties, which were ascribed to the presence of traces of dioxy geny 1 tetrafluoroborate (above). 

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