2,2,2 ,2 -Tetrafluoro protonation

For instance, the Dow experimental membrane and the recently introduced Hyflon Ion E83 membrane by Solvay-Solexis are "short side chain" (SSC) fluoropolymers, which exhibit increased water uptake, significantly enhanced proton conductivity, and better stability at T > 100°C due to higher glass transition temperatures in comparison to Nafion. The membrane morphology and the basic mechanisms of proton transport are, however, similar for all PFSA ionomers mentioned. The base polymer of Nation, depicted schematically in Figure 6.3, consists of a copolymer of tetrafluoro-ethylene, forming the backbone, and randomly attached pendant side chains of perfluorinated vinyl ethers, terminated by sulfonic acid head groups. °... 

An unusual loss of an aromatic nitro group as nitrite is observed during the reduction of 1,2,4,5-tetrafluoro-3,5-dinitrobenzene in DMF containing a proton donor [150]. 

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. 

Sulfonyl fluorides have not been much used as sources of sulfenes, presumably because of their low reactivity relative to, say, sulfonyl chlorides. Phenylmethanesulfonyl fluoride does not react with triethylamine under mild conditions, but does react with p-toluidine in methanol at 45 °C after a few days the deuterium exchange pattern was consistent with sulfene formation by an (ElcB)rev mechanism93. The mechanism of the reaction of phenylmethanesulfonyl fluoride evidently changes with conditions, since Williams and coworkers had observed that its reaction with aqueous hydroxide showed rate-controlling proton transfer, as in either an E2 or (ElcB)irr process46. Sulfonyl fluorides have been proposed as sulfene sources from such fluorinated sulfonyl fluorides as 1,2,2,2-tetrafluoro-ethanesulfonyl fluoride by Knunyants and Sokol skii and coworkers94. 

Lin HL, Huang JR, Chen YT et al (2012) Polybenzi-midazole/poly(tetrafluoro ethylene) composite membranes for high temperature proton exchange membrane fuel cells. J Polym Res 19 9875-9878... 

Protonation reactions of indenyl-ruthenium(ll) monohydrides [RuH( -C9H7)(L )(L )] with triflic or tetrafluoro-boric acid have been explored at —60°C, the nature of the resulting products being also strongly dependent on the... 

A set of experimental /hhi /hfi /ff and /cf couplings across one up to five bonds measured in different solvents and their DFT calculated values has been reported by Perez-Torralba et for two novel tetra-fluorinated 1,5-benzodiazepinones, i.e. 6,7,8,9-tetrafluoro-4-methyl-l,3-dihydro-2i -l,5-benzodiazepin-2-one and 6,7,8,9-tetrafluoro-l,4-dimethyl-l,3-dihydro-2ff-l,5-benzodiazepin-2-one. In the spectrum of the latter the 7hf coupling of about 4.5 Hz (/hf9 calcd. = 6.6 Hz) between the protons of the N-methyl group and F9 has been observed. A related coupling of 4.8 Hz has been reported in the literature for 2-fluoroacetophenone. It should be noted that the nature of this coupling is not obvious, it can be either through five bonds or through space. 

Further support for the above conclusions is provided by the resistance shown by perfluoro-(3-methylbuta-l, 2-diene) towards attack by hydrogen fluoride, chloride, and bromide at ambient temperatures protonation of the central allenic carbon in this allene would be expected to prove more difficult than in perfluoropenta-1,2-diene owing to the replacement of the fluorine at C-3 by trifluoromethyl, just as the same structural change in tetrafluoro-allene reduces the susceptibility of the system to protonation. 

The monoprotonated tetrafluoro-p-benzosemiquinone radical has been prepared from the parent quinone by photochemically-induced hydrogen-atom abstraction in a variety of solvents. The radical dissocates readily in hydroxylic solvents and in some cases rapid proton-transfer equilibria have been observed which give time-averaged e.s.r. spectra. ... 

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