title: The Activation of Carbon-Chlorine Bonds in Per- and Polyfluoroalkyl Chlorides: DMSO-Induced Hydroperfluoroalkylation of Alkenes and Alkynes with Sodium Dithionite.
abstract: In DMSO, the addition reactions of perfluoroalkyl chlorides, R(F)Cl, to alkenes or alkynes can occur smoothly in the presence of 1.5 equiv of Na(2)S(2)O(4) and NaHCO(3) at 75-80 degrees C for 4-10 h to give the corresponding adducts (RCH(2)CH(2)R(F) or RCH=CHR(F)). Ethyl chlorofluoro- (1f), chlorodifluoro- (1g) acetates, even nonfluorinated compounds, such as ethyl dichloro- (1h), chloro- (1i) acetates, and chloroform (1j) can undergo the similar reaction. Treatment of omega-iodo (or chloro-) perfluoroalkyl chlorides [X(CF(2))(n)()Cl, n = 2, 4, X= I or Cl] with >3 equiv of alkenes and Na(2)S(2)O(4) gives directly the symmetrically disubstituted alkanes (RCH(2)CH(2))(2)(CF(2))(n)(). The symmetrically and unsymmetrically disubstituted adducts RCH(2)CH(2)(CF(2))(n)()CH(2)CH(2)R' from omega- iodoperfluoroalkyl chlorides can be also obtained stepwise, i.e., through the further addition reactions of monoadducts, RCH(2)CH(2)(CF(2))(n)()Cl to olefins. However, for alpha,omega-dichloroperfluoroalkanes, the similarly stepwise reactions with an alkene is not clean, both bis-adducts and the corresponding omega-hydrides, RCH(2)CH(2)(CF(2))(n)()H as byproducts are also formed. In the absence of alkenes or alkynes, per- and polyfluoroalkyl chlorides can be converted to their sulfinate salts and sulfonyl chlorides.
authors.affiliation: Laboratory of Fluorine Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 354 Fenglin Lu, 200032 Shanghai, China.
authors.forename: Zheng-Yu
authors.initials: ZY
authors.lastname: Long
authors.forename: Qing-Yun
authors.initials: QY
authors.lastname: Chen