Compounds of formula CH.sub.2 Y--CH(COOR.sub.1)--O--CF.sub.2 CF.sub.2
--SO.sub.2 F, usable in the synthesis of the fluorosulphonic vinylether
--CF.sub.2.dbd.CF--O----CF.sub.2 CF.sub.2 --SO.sub.2 F.
Samenstellingen van formule CH.sub.2 Y -- CH(COOR.sub.1) -- O -- CF.sub.2 CF.sub.2 -- SO.sub.2 F, bruikbaar in de synthese van fluorosulphonic vinylether CF.sub.2.dbd.CF-o-cF.sub.2 CF.sub.2 -- SO.sub.2 F.
