Methods for producing perfluoroalkanedi(sulfonyl chloride)

A method for preparing a perfluoroalkanedi(sulfonyl chloride) having a formula (I) as follows:

• ClSO2CF2(CF2)nCF2SO2Cl (I)
• the method comprising:
• a first step of reacting a dibromoperfluoroalkane having a formula (II):
• BrCF2(CF2)nCF2Br (II)
• with SO2 radical anion or a source of SO2 radical anion;
• a second step of reacting the reaction mixture obtained in step one with a halogen selected from a group consisting of chlorine (Cl2), bromine (Br2), and interhalogen compounds consisting of chlorine atom and bromine atom, to form a perfluoroalkanedi(sulfonyl halide) having a formula (III):
• XSO2CF2(CF2)nCF2SO2X′ (III);
• a third step of reacting the obtained perfluoroalkanedi(sulfonyl halide) with an organic compound to form a perfluoroalkanedi(sulfinate) having a formula (IV):
• MO2SCF2(CF2)nCF2SO2M (IV);
• and a fourth step of reacting the perfluoroalkanedi(sulfinate) with chlorine (Cl2) to form perfluoroalkanedi(sulfonyl chloride);
• in which:
• n is a whole number from one to eight, X and X′ are independently a bromine atom or a chlorine atom, and M is a hydrogen atom, a metal atom, an ammonium moiety, or a phosphonium moiety.