Darstellung einiger perfluorbenzol-di-, tri- und tetrasulfonsäuren

1,2,3,4-Tetrafluorbenzenesulfonic acid, 1,2,4,5-tetrafluorobenzenesulfonic acid, 1,2,3,5-tetrafluorobenzenedisulfonic acid, 1,3,5-trifluorobenzene-2,4-disulfonic acid and 1,3,5-trifluorobenzenetrisulfonic acid are obtained by sulfonation of the three isomeric tetrafluorobenzenes, and of 1,3,5-trifluorobenzene, with stabilized SO₃ at normal pressure. Starting from dilithium 1,2,3,4-tetrafluorobenzenedisulphinate 1,2,3,4-tetrafluorobenzenedisulfonic acid can be prepared via oxidation with hydrogen peroxide. Fluorine displacement reactions lead to 1-thiol-2,3,5-trifluorobenzenedisulfonic acid, 1-thiol-2,3,6-trifluorobenzenedisulfonic acid, 1-thiol-2,4,5-trifluorobenzenedisulfonic acid, 1-thiol-2,5-difluorobenzenetrisulfonic acid and 1-thiol-3,5-difluorobenzenetrisulfonic acid, which can be converted into 1,2,4-trifluorobenzenetrisulfonic acid, 1,3-difluorobenzenetetrasulfonic acid and 1,4-difluorobenzenetetrasulfonic acid by oxidation procedures. N.m.r. parameters of the new compounds are described.