Sulfinated polymers

The production of industrially important perfluoroalkane sulfonic acids is generally accomplished by electrochemical fluorination. This method of preparation remains expensive and proceeds in good yields only for short hydrocarbon chains.30 Recently however, Wakselman and Tordeux have described a chemical method for the preparation of trifluoromethane sulfonic acid.31 The procedure involves reaction of a metal selected from zinc, cadmium, manganese, and aluminum with sulfur dioxide in DMF, followed by the introduction of trifluoromethyl bromide under slight pressure. The intermediate sulfinate is subsequently oxidized by hydrogen peroxide, and then hydrolyzed which leads to formation of the trifluoromethane sulfonic acid. Successful extension of the sulfination process to the modification of PCTFE should result in the formation of a sulfinated polymer which can ultimately be oxidized to give a sulfonic-acid modified polymer. 

Kerres s group synthesized several different types ofbasic, sulfonated or sulfinated polymer, and developed blend concepts for the fuel cell ionomer membranes [107—... 

The membrane in a PEM cell is made from a sulfinate polymer Nafion, which only lets protons through because there are sulfinate (SO4) molecules in the polymer, which contain oxygen atoms that are slightly negatively charged. The positively charged protons can weakly bind to them, which allows protons to permeate the membrane, and jump from one sulfinate molecule to another across the membrane with help from thermal fluctuations and the electric field created across the membrane by the electron flow (Figure 7.10). 

Cross-linked blend membranes by mixing sulfonated polymers with sulfinated polymers and the cross-linker in a dipolar-aprotic solvent (mostly NMP)... 

The synthesis of 4,5-disubstituted triazoles shown in Scheme 208, carried out on a polymer support with microwave assistance, is based on a similar principle. In the first step, sulfinate 1248 is converted to sulfone 1249. Condensation with aldehydes provides vinyl sulfones 1250. Cyclocondensation of sulfones 1250 with sodium azide generates corresponding triazoline intermediates that eliminate sulfinate 1248 to provide triazoles 1251 in moderate to good yield <2006OL3283>. 

Glycosides, synthesis of, 64, 2 Glycosylating agents, 68, 2 Glycosylation on polymer supports, 68, 2 Glycosylation, with sulfoxides and sulfinates, 64, 2... 

The sulfinated PCTFE derivative was converted to the sulfonated derivative by stirring the sulfinate in 30 wt % hydrogen peroxide/tetrahydrofuran for 2 days. The infrared spectrum (Figure 3) for the product polymer indicates formation of the sulfonated resin. 

Cheng et al. [316] synthesized the polymer-bound 2-sulfony-l, 3-dienes from the corresponding support-bound suhblene, which upon thermal S02-extrusion gave the highly reactive diene (345), which could be trapped with dienophiles. The synthesis on a polystyrene support begins with polymer-bound lithium phenyl-sulfinate. S-Alkylation with trans-3, 4-dibromosulfolane (343) in the presence of pyridine gave the resin-bound 3-(phenylsulfonyl)-3-sulfolene. Thermal SO2 extrusion had to be performed in xylene under reflux, which restricts the use of this reaction to PS/DVB-resins. Neither the IRORY-Kans [317] nor the Synphase Crowns [199], which are made of polypropylene, are compatible with these reaction conditions, in which polypropylene is dissolved (Scheme 72) ... 

Synthesis of a polymer-bound methyl sulfone (R H) (Scheme 70) [314] Polystyrene bearing lithium sulfinate (332) (3.51 g) was allowed to swell in THF... 

PS/DVBsulfonyl)-3-sulfolene (Scheme 72) A suspension of polymer bearing lithium sulfinate (332) (10 g, 8 mmol), trans-3,4-dibromosulfolane (llg, 40 mmol), and pyridine (3.2 mL, 40 mmol) was stirred at 80 °C for 48 h, after which time the reaction was cooled to r. t., quenched with water, and filtered. The resin was washed as follows ... 

It should be noted that in addition to aeid-eatalyzed deproteetion of some of the protected forms of the above-mentioned resins, namely, poly(4-tert-butoxy-a-methylstyrene) and poly(4-rerr-butoxycarbonyloxystyrene sulfone), these resins are believed to undergo main chain scission under DUV irradiation. The poly(4-tert-butoxycarbonyloxystyrene sulfone) is believed to produce sulfinic or sulfonic acid through scission of the backbone C—S bond on x-ray irradiation, although it has a somewhat poor sensitivity to DUV. Because the resist polymer itself generates an acid that deprotects the r-BOC group, this system constimtes a rare example of a one-component chemical amplification resist (see Scheme 7.31). ... 

Polymer-supported alkynyliodonium tosylates 34 can be prepared by treatment of reagent 4 with terminal alkynes in the presence of p-toluenesulfonic acid (Scheme 5.20) [57]. Polymers 34 are effective alkynylating reagents toward sodium sulfinates and benzotriazole [57]. 

J. Kerres, W. Cui, S. Reichle, New sulfonated engineering polymers via the metalation route. I. Sulfonated poly(ethersulfone) PSU Udel via metalation-sulfination-oxidation. Journal of Polymer Science Part A Polymer Chemistry 1996, 34(12), 2421-2438. 

Uozumi and coworkers prepared phosphine/palladium complexes supported on polyethylene glycol-polystyrene graft polymer. - This amphiphilic resin-supported palladium complex eftidently catalyzed the alkylation of allylic acetates in water with various nucleophiles including 1,3-dicarbonyl compounds, amino acids, sodium azide, sodium sulfinate, phenylboronic acid, and sodium tetraphenylborate to give the corresponding allylic-substituted products in quantitative yields. 

Pyrazoline, Isoxazoline, andBenzofb][1,4Jdiazepine Derivatives. The sulfone linker 44 derived Irom 43 is a versatile and robust tether and many new applications of this linker have been explored. To demonstrate the use of 44 as a versatile and robust tether that offers various on-resin functionalization or cleavage with additional changes, Lam and coworkers have highlighted the preparation of the five-membered pyrazoUne/isoxazoline 48 as well as the fused benzodiazepine 47 (Scheme 12.11). The polymer-bound sodium sulfinate resin 43 was treated with benzyl bromide using NBU4I/KI/DMF to yield 5-alkylated sulfone... 

Synthesis of Pyrimidine Derivatives. In 2002, Lam and coworkers reported the use of polystyrene/1 % divinylbenzene sodium sulfinate 43 as solid-phase support for the synthesis of pyrimidine derivatives (Scheme 12.33)." Resin 43 in NBU4I/KI/DMF was allowed to react with l,3-dichloropropane-2-one at room temperature to yield the polymer-supported a-haloketones 159. Treatment of resin 159 with substituted aminopyridines in anhydrous DME yielded the imidazo[l,2-a]pyridine resin 160. Alkylation of resin 160 occurs selectively with cw-epoxide and not the trans isomer to give resin 161, which could be... 

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