[GRAPHICS]
Room-temperature ionic liquids, 1-butyl-3-methylimidazolium hexafluorophosp
hate, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidaz
olium bromide, and 1-butyl-3-methylimidazolium chloride, are used as "green
" recyclable alternative to chlorinated solvents for the stereoselective ha
logenation of alkenes and alkynes.