A method for producing a fluorosulfonyl group-containing compound to obtain a compound represented by the following formula 5 from a compound represented by the following formula 1 as a starting material and a method for producing a fluorosulfonyl group-containing monomer in which the fluorosulfonyl group-containing compound is used: ##STR00001##
wherein R.sup.1 and R.sup.2 are a C.sub.1-3 alkylene group, and R.sup.F1 and R.sup.F2 are a C.sub.1-3 perfluoroalkylene group.

Presently described is a monomer having the formula: ##STR00001##
wherein n ranges from 2 to 8; Y is F or C.sub.mF.sub.2m+1; a is 0, or averages 1 to 2; m is independently 1, 2, 3, or 4; and X is F or OH. Also described is a method of making such monomer, various compounds prepared during while making the monomer, fluoropolymers comprising polymerized units of such monomer, fuel cell membranes, membrane electrode assemblies, and methods of making fluoropolymers.

Presently described is a monomer having the formula: ##STR00001##
wherein n ranges from 2 to 8; Y is F or C.sub.mF.sub.2m+1; a is 0, or averages 1 to 2; m is independently 1, 2, 3, or 4; and X is F or OH. Also described is a method of making such monomer, various compounds prepared during while making the monomer, fluoropolymers comprising polymerized units of such monomer, fuel cell membranes, membrane electrode assemblies, and methods of making fluoropolymers.