The reactions of perfluoro- and α,α-dichloropolyfluoroalkanesulfinates

Abstract

Sodium perfluoroalkanesulfinate, RFSO2Na [RFCl(CF2)4, 1a; CF3(CF2)5, 1b; Cl(CF3)6, 1c] reacted with bromine in aqueous solution to give the corresponding sulfonyl bromide RFSO2Br (2a-2c) and in acetonitrile or acetic acid, to form perfluoroalkyl bromide RFBr (3a-3c). Heating in acetonitrile at 80°C, 2a-2c were converted smoothly into 3a-3c. However, reaction of sodium α,α-dichloropolyfluoroalkanesulfinate RCCl2SO2Na (RCF3, Cl(CF2)n, n=2, 4, 6, 5a-5d) with bromine in aqueous solution gave directly the corresponding bromoalkanes 1-bromo-1,1-dichloropolyfluoroalkane RCCl2Br (6a-6d). In aqueous potassium iodide solution, 1a-1c, 5a and 5b also reacted with iodine to form the corresponding iodo-polyfluoroalkane 4a-4c, 7a and 7b directly. 6a and 7a underwent free radical addition to alkene readily in the presence of free radical initiator and reacted with Na2S2O4 in the usual way to form α,α-dichloropolyfluoroethane sulfinate (5a). 5a was stable in strong acid, but reacted with strong base to yield 10. 5a was oxidised by hydrogen peroxide to the sulfonate 11 and reduced by zinc in dilute acid to from the α-chloro sulfinate 12.