Polymeric resin sulfonic acids

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

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. 

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. 

Purification Ion-exchange Using Polymeric Supported Sulfonic Acid. Dowex 50W has also found use as an ion-exchange resin for the purification of amine derivatives. Ham-merschmidt has purified a substituted amine 88, after a Boc deprotection of 87 with HCl (6 M) (eq 40), whereas Najera used the same resin to purify phenylalanine (90) after cleavage from the corresponding oxazolidinone (89) with lithium hydroxide (eq 41). ... 

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

The term novolac refers to the early use of phenolic to replace expensive shellac-based coatings. Novolacs are now those resins made at formaldehyde-to-phenol molar ratios of less than one-to-one. They are generally, though not always, manufactured under acidic conditions. Sulfuric or oxalic acids are most often chosen as catalyst though aromatic sulfonic acids and phosphoric acid are also quite common. Many other acids are used for special purposes. The finished novolac resin is incapable of further polymerization or crosslinking and therefore... 

Other Polymerization Methods. Experimental allemalives include the use of peroxides, hydrogen fluoride, a sulfonic acid ion-exchange resin, and corona discharge. 

Examples are the sulfonating of polyethylene film with chloro-sulfonic acid (60) the sulfonating of sheets of phenolformaldehyde resin (77) the treatment of a film consisting of polystyrene and polyvinylchloride with concentrated sulfuric acid (4) the sulfonating of films consisting of aliphatic vinylpolymers with chlorosulfonic acid (125) the sulfonating of copolymers of a monovinyl- and a polyvinyl compound (30). Also are used copolymers of aromatic monovinyl-compounds and linear aliphatic polyene hydrocarbons (3) copolymers of an unsaturated aromatic compound and an unsaturated aliphatic compound (76), and of reaction products of poly olefines and partially polymerized styrene (173). 

The reaction of TFP resin with sulfonyl chlorides (3 equiv.) in the presence of diisopropylamine (DIEA 3 equiv.) provides the corresponding sulfonate-activated resins (Fig. 2). Alternatively, sulfonic acids may be loaded directly onto TFP using DIC (via the intermediate sulfonic acid anhydride) as the coupling reagent. Analogous to the carboxylate esters, the sulfonate ester resins are stable when dry and may be kept at room temperature for an extended period of time without decomposition. This is one of the clear advantages of the polymeric TFP reagents versus acid chlorides the latter decompose once exposed to air and moisture. 

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