Nafion polymeric resin

Polymeric resin sulfonic acids including sulfonic acid resins complexed with Lewis acids and perfluorinated polymer resin acids (Nafion-H and Nafion-silica nanocomposites). 

The HX formed as a byproduct of the termination reaction can be a nuisance. If left in the polymer, these strong acids result in degradation and discoloration of the PTHF. Furthermore, the strong acids are also very corrosive to pol)rmerization reactors. One anion that overcomes these problems is Nafion (SO3 form) (24), which is a polymeric resin produced by duPont. After... 

Nafion-H (144), a perfluorinated resin-sulfonic acid, is an efficient Bronsted-acid catalyst which has two advantages it requires only catalytic amounts since it forms reversible complexes, and it avoids the destruction and separation of the catalyst upon completion of the reaction [94], Thus in the presence of Nafion-H, 1,4-benzoquinone and isoprene give the Diels-Alder adduct in 80% yield at 25 °C, and 1,3-cyclohexadiene reacts with acrolein at 25 °C affording 88 % of cycloadduct after 40 h, while the uncatalyzed reactions give very low yields after boiling for 1 h or at 100 °C for 3.5 h respectively [95], Other examples are given in Table 4.24. In the acid-catalyzed reactions that use highly reactive dienes such as isoprene and 2,3-dimethylbutadiene, polymerization of alkenes usually occurs with Nafion-H, no polymerization was observed. 

Nafion SAC-13 exhibited the highest activity and selectivity in the dehydration of 1 - and 2-hexanol and cyclohexanol to alkenes in the gas phase over various solids in the temperature range of 200-300°C.738 Furthermore, it did not show the dramatic decrease in activity when compared to zeolites rather, it exhibited an initial activity increase. This was attributed to solvation of the polymeric matrix by the water vapor formed in the process. This served to swell the resin, rendering previously inaccessible sites available to the reactants. 

Nafion-H is a convenient acid catalyst for pinacolone rearrangements. Hydration of acetylenes can be conducted with Nafion-H impregnated with mercury(II) ions. Diels-Alder catalyst. This protic resin catalyzes Diels-Alder reactions, but longer reaction times are needed than in reactions catalyzed by Lewis acids. The reactions are generally conducted in refluxing benzene or chloroform. In the case of dienes that polymerize readily, the reaction is conducted at room temperature for 1-2 days.°... 

Olah, G. A., Arvanaghi, M., Krishnamurthy, V. V. Heterogeneous catalysis by solid superacids. 17. Polymeric perfluorinated resin sulfonic acid (Nafion-H) catalyzed Fries rearrangement of aryl esters. J. Org. Chem. 1983,48, 3359-3360. 

Figure 2. Crown ethers identified by chemical ionization mass spectroscopy for EO/THF polymerization using Nafion perfluorosulfonic acid resin as catalyst.

Another industrial route to obtain a,oo hydroxy-telechelic PTHF is based on the transfer reaction with anhydrides (7.11). The polymerisation reaction is based on a mixture of anhydrides (usually acetic anhydride) and a superacid (HSbF6, HC104, CF3S03H or even in the presence of a polymeric superacid with -CF2-CF2-S03H groups (Nafion resins, solid analogue of triflic acid) [26, 27] or Lewis acids (BF3, SbF5) [20, 24], or solid acidic clays [29]. The real catalyst is the oxocarbenium salt formed by the reaction of acetic anhydride and the superacid ... 

With a soluble perfluorlnated acid, CF-SO H, a linear dimer was the primary product In non-polar solvents. The solid, strong acid catalyst retained catalytic activity on repeated reaction, had higher activity than that of a conventional poly-(styrenesulfonlc acid) resin and was virtually free of solvent effects on the reaction rate and product composition. The perfluorlnated polymeric catalyst was not very effective when compared with CF-S0,H a ten-fold excess of NAFION relative to CF.SO.H was required to give oligomerizations with a similar rate In CCl, at 50 C. 

Wu Z, Sun G, Jin W, Wang Q, Hou H, Chan KY, Xin Q (2007) Use of in situ polymerized phenol-formaldehyde resin to modify a Nafion membrane for the direct methanol fuel cell. J Power Sources 167 309-314... 

Nafion-H, a polymeric perfluorinated resin sulfonic acid, in refluxing nitrobenzene for 12 h (71%) [38]. 

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