N-bromosuccinimide, usually referred to as NBS for short, is the nitrogen-brominated imide of succinic acid.

Regioselective bromination

NBS reacts in the light with allylic and benzylic protons with substitution. This reaction is known as the Wohl-Ziegler reaction. Elemental bromine, on the other hand, reacts with the addition of the corresponding alkenes or with core substitution with the aromatics.


NBS in aqueous dioxane is an extremely selective oxidizing agent. In contrast to reagents such as the Cornforth reagent (PDC) and pyridinium chlorochromate (PCC), secondary alcohols are preferentially oxidized in very good yields over primary alcohols.

Bromohydrin formation

Alkenes react in aqueous dimethyl sulfoxide (DMSO) to form the bromohydrins, the so-called Dalton reaction. These are important starting materials for the formation of epoxides. In contrast, bromoketones are obtained in anhydrous DMSO. In the case of enol ethers, the α-bromocarboxylic acid esters are obtained, which can be starting materials for the important Reformatzki reaction.

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