脱卤亚磺化研究——连二亚硫酸钠作为新的脱卤亚磺化试剂

全氟碘代烷与亚硫酸盐发生单电子转移反应生成全氟亚磺酸盐;连二亚硫酸钠水溶液热分解时,ESR表明生成SO_2~-主阴离子自由基,这两者促使我们尝试用连二亚硫酸钠代替亚硫酸盐与全氟卤代烷反应.实验表明对于全氟碘代烷及溴代烷它是一种有效的

Studies on dehalo-sulfination sodiumdithionitte as a new dehalo-sulfinating agent

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.