REACTION OF PERFLUOROARYL HALIDES WITH REDUCED SPECIES OF SULFUR DIOXIDE (HSO2(-), SO2(2-), S2O4(2-))

Article abstract of DOI:10.1016/S0022-1139(00)80493-5

Rongalite (sodium hydroxymethanesulfinate), sodium dithionite, and aminoiminomethanesulfinic acid (AIMS) reduce perfluoroiodobenzene in N,N-dimethylformamide to pentafluorobenzene.In the presence of added D2O or CH3OD, deuteriopentafluorobenzene is formed. p-Dinitrobenzene does not inhibit the reduction, and addition of norbonene did not result in trapping of any radical intermediates.Reaction of pentafluoroiodobenzene with sodium benzenesulfinate gave 1,4-dibenzenesulfonyl-2,3,5,6-tetrafluorobenzene.A halophilic attack mechanism is suggested for the reduction reaction.Chloropentafluorobenzene did not react under the same conditions as the iodide; at elevated temperatures in the presence of sodium bicarbonate and Rongalite the fluorine para to the chlorine was reduced.Reduction of the chloride to pentafluorobenzene is minor.In the absence of bicarbonate, the chloride gave also a mixture of sulfides believed to be derived from decomposition of the Rongalite to hydrogen sulfide.Some reaction with dimethylamine from decomposition of DMF also is observed.