Synthesis of partially fluorinated monomers and polymers for ion-exchange resins

Novel hydrofluorovinyl ethers CF2=CFOCH2CF2CF2SR (R=methyl (2a) and tert-butyl (2b)) were prepared using tetrafluoroethylene as the only fluorinated starting material. Another monomer, CF2=CFOCH2CF2CF2SO2C(CH3)(3) (2C), was obtained by oxidation of an intermediate with the HOF reagent produced from fluorine and water in acetonitrile. The vinyl ethers 2a-c homopolymerize under typical free radical conditions to give low to moderate molecular weight amorphous polymers. These monomers readily copolymerize with tetrafluoroethylene to give higher molecular weight copolymers which can be melt fabricated into films. Copolymer compositions are essentially identical to monomer feed compositions. The S-tert-butyl pendant groups are converted cleanly to sulfonyl chlorides in one step using chlorine and aqueous trifluoroacetic acid. Chlorination (Cl-2) of the S-methyl or S-tert-butyl substituted polymers affords the corresponding sulfenyl chlorides which can be oxidized to sulfonyl chlorides by chlorine and aqueous acid or aqueous sodium hypochlorite. Alternatively, the S-tert-butyl groups can be oxidized to sulfones using the HOF reagent. Reaction of the tert-butylsulfones with chlorine or bromine trifluoride provides sulfonyl chlorides or fluorides, respectively. (C) 1999 Elsevier Science S.A. All rights reserved.