text: Many sulfonic acids are prepared by hydrolysis of sulfonyl halides and related precursors.  Thus, perfluorooctanesulfonic acid is prepared by hydrolysis of the sulfonyl fluoride, which in turn is generated by the electrofluorination of octanesulfonic acid. Similarly the sulfonyl chloride derived from polyethylene is hydrolyzed to the sulfonic acid.  These sulfonyl chlorides are produced by free-radical reactions of chlorine, sulfur dioxide, and the hydrocarbons using the Reed reaction.
  Vinylsulfonic acid is derived by hydrolysis of carbyl sulfate, (), which in turn is obtained by the addition of sulfur trioxide to ethylene.