In contrast to R_FSO_3CH_2R(1)(R=hydrogen,alkyl and perfluorcalkyl)and R_FSO_3CF_2R_F(2),the reactions of difluoromethyl perfluoroalkanesulfonates R_FSO_3CF_2H(3)with nucleophiles aremore complicated.Halide inos,X|-(X=F,Cl,I)and ethanol only attack the alkoxyl carbon atom,cleaving the C-O bond to give HCF_2X(4)and HCF_2OEt(5)respectively.Other reagents such asRCO_2|-(R=CH_3,CF_3),C_6H_5S|-etc.can either attack the carbon or sulfur atom of 3 to give the cor-responding products of C-O and S-O bond cleavages.More basic nucleophiles RO|-(R=C_6H_5,Et)mainly abstract the proton of the HCF_2 moiety to produce difluorocarbene.Ether and benzene,which can be alkylated by methyl perfluoroalkanesulfonate,do not react with 3 under similar con-ditions.The reaction rate of 3 with KF is much slower than that of 1(R=H).All these data seemto indicate that the shielding effect caused by the two fiuorine atoms on the methyl carbon in 3 preventsto some extent the nucleophilic attack on this carbon,but not so completely as in 2 due to the presenceof a hydrogen atom. In contrast to R_FSO_3CH_2R (1) (R = hydrogen, alkyl and perfluorcalkyl) and R_FSO_3CF_2R_F (2) ) and ethanol only attack the alkoxyl carbon atom, cleaving the CO bond to give HCF_2X (4) and HCF_2OEt (5) respectively. Other reagents such as RCO_2 | - (R = CH_3, CF_3), C_6H_5S | -etc.can either attack the carbon or sulfur atom of 3 to give the cor-responding products of CO and SO bond cleavages. More basic nucleophiles RO | - (R = C_6H_5, Et) mainly abstract the proton of the HCF_2 moiety to produce difluorocarbene.Ether and benzene, which can be alkylated by methyl perfluoroalkanesulfonate, do not react with 3 under similar conditions. The reaction rate of 3 with KF is much slower than that of 1 (R = H) .All these data seem to indicate that the shielding effect caused by the two fiuorine atoms on the methyl carbon in 3 preventsto some extent the nucleophilic attack on this carbon, but not so completely as in 2 due to the presenceof a hydrogen atom.