N-bromosuccinimide

Definition

N-bromosuccinimide (NBS) is a versatile organic reagent used in various chemical reactions, particularly in the context of alkene functionalization, aromatic substitution, and oxidation of aromatic compounds. It serves as a source of electrophilic bromine and is commonly employed in reactions such as halohydrin formation, allylic bromination, and aromatic substitution.

5 Must Know Facts For Your Next Test

1. N-bromosuccinimide is commonly used in the formation of halohydrins from alkenes through the addition of hydrohalic acids (HO-X).
2. In the context of preparing alkyl halides from alkenes, NBS can undergo allylic bromination, selectively introducing a bromine atom at the allylic position.
3. NBS can participate in various aromatic substitution reactions, including halogenation, nitration, and sulfonation, by generating electrophilic bromine species.
4. The oxidation of aromatic compounds can be achieved using NBS, which can act as a mild oxidizing agent, converting alcohols to aldehydes or ketones.
5. The succinimide moiety in NBS acts as a stabilizing group, enhancing the reactivity and selectivity of the bromine species generated during the reactions.

Review Questions

• Explain the role of N-bromosuccinimide in the formation of halohydrins from alkenes through the addition of hydrohalic acids (HO-X).
  • In the context of 8.3 Halohydrins from Alkenes: Addition of HO-X, N-bromosuccinimide (NBS) can be used to facilitate the formation of halohydrins. NBS acts as a source of electrophilic bromine, which can add to the alkene, forming a bromonium ion intermediate. This intermediate is then attacked by the hydrohalic acid (HO-X), resulting in the formation of the halohydrin product. The succinimide moiety in NBS helps stabilize the bromine species, enhancing the reactivity and selectivity of the overall reaction.
• Describe how N-bromosuccinimide can be used in the preparation of alkyl halides from alkenes through allylic bromination, as discussed in 10.3 Preparing Alkyl Halides from Alkenes: Allylic Bromination.
  • In the context of 10.3 Preparing Alkyl Halides from Alkenes: Allylic Bromination, N-bromosuccinimide (NBS) can be employed to selectively introduce a bromine atom at the allylic position of an alkene. NBS can generate bromine radicals through radical initiation, which then abstract a hydrogen atom from the allylic position, forming a stabilized allylic radical. This radical can then be trapped by the bromine species, resulting in the formation of the allylic bromide product. The selectivity of this reaction is due to the stabilization of the allylic radical intermediate.
• Discuss the role of N-bromosuccinimide in various aromatic substitution reactions, as described in 16.2 Other Aromatic Substitutions, and its use in the oxidation of aromatic compounds, as covered in 16.8 Oxidation of Aromatic Compounds.
  • In the context of 16.2 Other Aromatic Substitutions and 16.8 Oxidation of Aromatic Compounds, N-bromosuccinimide (NBS) can participate in a variety of reactions involving aromatic compounds. NBS can generate electrophilic bromine species, which can undergo substitution reactions with aromatic rings, such as halogenation, nitration, and sulfonation. Additionally, the oxidative properties of NBS can be utilized to convert aromatic alcohols to aldehydes or ketones, as described in 16.8 Oxidation of Aromatic Compounds. The succinimide moiety in NBS helps stabilize the reactive bromine species, enabling these selective and controlled aromatic transformations.

Related terms

Succinimide: Succinimide is a cyclic imide compound with the formula C₄H₅NO₂, which serves as the core structure of N-bromosuccinimide.

Electrophilic Bromination: Electrophilic bromination is a reaction where bromine, often generated from NBS, is introduced into an organic molecule in the presence of an electrophilic species.

Radical Initiation: Radical initiation is a process where NBS can generate bromine radicals, which can then participate in radical chain reactions, such as allylic bromination.