 The fluorides are more resistant than the corresponding chlorides and are therefore better suited to this task.Sulfonyl bromides have the general formula RSO2Br.In contrast to sulfonyl chlorides, sulfonyl bromides readily undergo light-induced homolysis affording sulfonyl radicals, which can add to alkenes, as illustrated by the use of bromomethanesulfonyl bromide, BrCH2SO2Br in Ramberg–Bäcklund reaction syntheses.