The present disclosure relates to the preparation of a compound of formula (I) comprising an SO.sub.2F function, RSO.sub.2F, by reacting a compound of formula (II), RSO.sub.2X, with a fluorinating agent, the process carried out in the liquid phase in the presence of hydrofluoric acid using an antimony-based fluorination catalyst, wherein R, R, and X are described herein.

The present disclosure relates to the preparation of a compound of formula (I) comprising an SO.sub.2F function, RSO.sub.2F, by reacting a compound of formula (II), RSO.sub.2X, with a fluorinating agent, the process carried out in the liquid phase in the presence of hydrofluoric acid using an antimony-based fluorination catalyst, wherein R, R, and X are described herein.

The present disclosure relates to the preparation of a compound of formula (I) comprising an SO.sub.2F function, RSO.sub.2F, by reacting a compound of formula (II), RSO.sub.2X, with a fluorinating agent, the process carried out in the liquid phase in the presence of hydrofluoric acid using an antimony-based fluorination catalyst, wherein R, R, and X are described herein.

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.

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.

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.