Sodium dithionite was found to be a new and versatile dehalo-sulfinating agent for perfluoroalkyl iodides and bromides. Water-soluble perfluoroalkyl iodides bearing -- SO3Na, -- CO2Na groups such as sodium 5-iodo-3-oxa-octafluoropentane sulfonate (1), 7-iodo-3-oxa-dodecafluoroheptane sulfonate (2),9-iodo-3-oxa-perfluorononane sulfonate (3), 5-iodo-3-oxa-hexafluoropentanoate (4),7-iodo-3-oxa-decafluoroheptanoate (5) and 5-iodo-3-oxa-octafluoropentane sulfinate (6) reacted with Na2SO4 in aquous solutions containing NaHCO3 to form the corresponding sulfinates 7-12 in high yields. When PTC such as hexadecyltrimethylammonium bromide, polyethyleneglycol-200-600 and cosolvents such as acetonitrile, diethyleneglycol were added to improve the solubility of water-insoluble perfluoroalkyl iodides in the aqueous reaction medium, the iodides such as 1-iodo-2-chlorotetrafluoroethane (13a), 1-iodo-4-chlorooctafluorobutane (13b), 1-iodo-6-chloro-dodecafluorohexane (13c), 1-iodo-8-hydroperfluorooctane (14) and 1,5-diiodo-3-oxa-octafluoropentane (15) were also transformed into the corresponding sulfinates 17a, 17b, 17c, 18 and 12 respectively in satisfactory yields. Furthermore, 5-iodo-3-oxa-octafluoropentane sulfonyl fluoride (16) can also be converted to 12 by using Na2S2O4-NaHCO3 reagent. Similarly, sodium 5-bromo-3-oxa-octafluoropentane sulfonate (19), 1-bromo-4-chlorooctafluorobutane (20) and u-hydro-8-bromo-hexadecafluorooctane (21) reacted with sodium dithionite to give the corresponding debromo-sulfination products 7, 17b and 18 in 50-80% yields. These fluorinated sulfinates were readily converted into the corresponding sulfonyl chlorides in the usual manner. applications of sodium dithionite in organofluorine chemistry through their elemental analyses, IR and 19F NMR spectroscopy.

Key words: SODIUM COMPOUNDS, SULFONATION, HALOHYDROCARBON, DEHALOGENATION REACTION, HYDROSULFITES, SULFINIC ACID, FLUOROCARBON, CARBOXYLATES