In practice,few alkenes are soluble in water,andbromohydrin formation is often carried out in a soluvent such as aqueous dimethyl sulfoxide, CH3SOCH3(DMSO) using a reagent called N-bromosucinimide(NBS) as a source of Br2. NBS is a stable,easily handled compoundthat slowly decompoces in water to yield Br2 at a controlled rate.Bromine itself can also be used in the addition reaction,but it is more dangerous and more difficult to handle then NBS.