Perfluorovinyl, derivatives

The compounds are characterized by 19F and H NMR, IR, and Raman spectral studies. Compounds of the type SF5ORf are thermally very stable. They do not yield the perfluorovinyl derivative, SF5OCF=CF2, on dehalogenation as is the case when CF3OCF=CF2 is formed from CF30CFC1CF2C1 (94). 

Perfluorovinyl Derivatives Table VIII). Perfluorovinyl metal compounds have F spectra which are considerably simpler than the proton spectra of vinyl metals. The differences in chemical shift of the three fluorines of the perfluorovinyl group are sufficiently great that the spectra are of the simple AMX type and appear as three quartets (Fig. 8). In some instances, however,... 

Little correlation was found between the F chemical shifts and the nature of the central atom in these perfluorovinyl derivatives, except for the boron compounds (56). In these compounds the shifts of fluorine atoms of the CF2 group are relatively unshielded compared with the corresponding absorptions in the other perfluorovinyl compounds. This may reflect a mesomeric effect involving the vinyl group s tt electrons and the boron atom. 

C=C stretch, as it appears for example in vinyl chloride, is diminished, often to a point where its assignment becomes uncertain. In the case of the perfluorovinyl group there is no significant lessening of the intensity of the C=C absorption when the CF2 CF— group is bonded to a metal rather than to a hydrogen or halogen atom. Liquid film spectra of three perfluorovinyl derivatives are reproduced in Fig. 3. 

This similarity in reactivities probably derives from a fortuitous cancellation of substituent effects in 11. Fluorination increases chain stiffness and creates an unfavorable polarity mismatch between an electrophilic radical and an electron-poor double bond, but this is offset by the significant decrease of 7r-bond energy in 11. The vinyl ether 12 analog cyclizes about seven times faster than 11, which is consistent with the known lower 7r-bond energy and higher free-radical reactivity of perfluorovinyl ethers vs perfluoroalkenes [142]. 

Photoresist compositions consisting of pentafluoromethylvinyl carbonate derivatives, (II), were prepared by Yoon [2] and used in photosensitive polymers for exposure to light sources having a dominant wavelength of less than 157 nm. Perfluorovinyl ether, (III), monomers were prepared by DiPietro [3] and used in lithographic photoresist polymer compositions. 

Perfluoropropynyl [15, 26, 27] and perfluorovinyl [16, 28-30]-lithium and -magnesium are considerably more stable than perfluoroalkyl derivatives, whilst the corresponding perfluoroaryl derivatives may be used as effectively as in the hydrocarbon series, and direct syntheses involving iodo compounds are also possible (Figure 10.3). 

Perfluorovinyl [112] and perfluoromethyl derivatives apparently undergo similar cleavage with aqueous alcoholic potassium fluoride. Fluorocarbon tin compounds may be used effectively in Stille coupling processes [15] (Figure 10.54). 

The development of new polymeric materials for polymer electrolyte fuel cell is one of the most active research areas, aiming at the new energy sources for electric cars and other devices. The mainstream of the material research for fuel cell is perfluoroalkyl sulfonic acid membranes such as Nafion, Acipex, and Flemion. The most well-known one is Nafion of Du Pont, which is derived from copolymers of tetrafluoro-ethylene and perfluorovinyl ether terminated by a sulfonic acid group.Protons, when dissociated from the sulfonic acid groups in aqueous environment, become mobile and the membrane becomes a proton conducting electrolyte membrane. 

Perfluorlnated ion-exchange membranes are derived from copolymers of tetrafluoroethylene (TFE) and a perfluorovinyl ether terminated by a sulfonyl fluoride group. The precursor of the perfluorinated membrane has the form... 

Recently, an extremely selective cyclopolymerization has been developed by using specially designed difunctional perfluoromonomers such as perfluoroallyl vinyl ether (13). This monomer is readily derived from the carboxylated perfluorovinyl ether according to the scheme shown above, and characterized by the different reactivities of the two double bonds, that is, a vinylether type and an allyl type. 

In addition to the perfluorosulfonic acid derivatives, carboxylic acid forms have been developed. These may be obtained by modification of Nafion films or by direct synthesis. In the case of modification, the ionomer is converted from a thionyl chloride to a carboxylic acid. Typical reducing agents are hydriodic acid, hydrobromic acid and hydrophosphonic acid. The carboxylic acid form can be made directly by copolymerization of tetrafluoroethylene and a carboxylated perfluorovinyl ether. The synthesis of the ether is a difficult task, however, as cyclization can occur. One synthetic route to the ether is shown in Scheme 5. After copolymerization with tetrafluoroethylene, the ester group can be quantitatively hydrolyzed to yield the sodium salt. 

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