N-Bromosuccinimide

Chemical Properties

white to light yellow crystalline powder

Uses

N-Bromosuccinimide is a brominated succinimide used as a chemical reagent in radical substitution and electrophilic addition reactions in organic synthesis. In bromination of olefins; in oxidation of alcohols to aldehydes and ketones and of aldehydes to acid bromides.

Definition

ChEBI: N-bromosuccinimide is a five-membered cyclic dicarboximide compound having a bromo substituent on the nitrogen atom. It has a role as a reagent. It is a dicarboximide, a pyrrolidinone and an organobromine compound. It is functionally related to a succinimide.

Preparation

N-Bromosuccinimide is prepared by addition of bromine to a cold aqueous solution of succinimide or by reaction of succinimide with NaBrO2 in the presence of HBr.

1.62mol (160g) succinimide is dissolved in a mixture of 1.60mol (64g) NaOH, 300g crushed ice and 400ml water. Cool the mixture in an ice bath, and add 85ml (1.65 mol, 264g) Br2 at once while stirring violently. Stir for two more minutes, then filter the precipitated product and wash with ice water. Dry in a desiccator. Yield 75-81%.
Don't clean up NBS too much, the stinky yellow stuff still containing a bit of Br2 works best. N-Bromosuccinimide is a brominating agent that replaces hydrogen atoms in benzylic or allylic positions. It is used in the oxidation of secondary alcohols to ketones and in controlled low-energy brominations.

Flammability and Explosibility

Non flammable

reaction suitability

reagent type: oxidant

Safety Profile

Poison by intraperitoneal route. An irritating poison to skin, eyes, and mucous membranes. Reacts explosively with adme, dtallyl sulfide, and hydrazine hydrate. Explosive reaction with propiononitrile after heating to 105℃ for 24 hours. Violent reaction with dtbenzoyl peroxide + 4-tok acid. When heated to decomposition it emits toxic fumes of Brand NOx. See also BROMIDES and NITROGEN MONOXIDE.

Purification Methods

N-Bromosuccinimide (30g) is purified by dissolving rapidly in 300mL of boiling water and filtering through a fluted filter paper into a flask immersed in an ice bath, and left for 2hours. The crystals are filtered off, washed thoroughly with ca 100mL of ice-cold water and drained on a Büchner funnel before drying under vacuun over P2O5 or CaCl2 [Dauben & McCoy J Am Chem Soc 81 4863 1959]. This brominating agent has also been crystallised from acetic acid or water (10 parts), washed in water and dried in vacuo [Wilcox et al. J Am Chem Soc 108 7693 1986, Shell et al. J Am Chem Soc 108 121 1986, Phillips & Cohen J Am Chem Soc 108 2013 1986, Beilstein 21/9 V 543.]