N -bromo succinimide

Structural formula
General
Surname	N -bromo succinimide
other names	NBS; N -bromobutanimide; 1-bromo-2,5-pyrrolidinedione; N -succinic acid imide;
Molecular formula	C 4 H 4 BrNO 2
Brief description	colorless, orthorhombic crystals
External identifiers / databases
EC number	204-877-2
ECHA InfoCard	100.004.435
PubChem	67184
Wikidata	Q286939
properties
Molar mass	177.99 g mol −1
Physical state	firmly
density	2.10 g cm −3
Melting point	174-179 ° C
Vapor pressure	0.0019 Pa (20 ° C)
solubility	little in water (14.8 g l −1 at 20 ° C); poor in diethyl ether , benzene and carbon tetrachloride ; soluble in acetone and ethyl acetate ;
safety instructions
H and P phrases	H: 302-314
	P: 280-305 + 351 + 338-310
Thermodynamic properties
ΔH f 0	−335.9 kJ / mol
	As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

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

Extraction and presentation

NBS can be made by treating succinimide with elemental bromine in the presence of sodium hydroxide solution at 0 ° C.

properties

NBS is sparse in water, but readily soluble in most organic solvents . Some solvents, such as tetrahydrofuran , N, N-dimethylformamide , N, N-dimethylacetamide , N, N-dimethylpropionamide , N-methyl-2-pyrrolidone and ethyl acetate, are not inert towards NBS and enter into exothermic reactions at elevated temperatures. NBS is not stable and should be stored at 2–8 ° C in the dark. Under strong mechanical and / or thermal stress, NBS can explode into bromine and nitrous gases .

Due to the higher electronegativity of nitrogen compared to bromine , reinforced by the two adjacent carbonyl groups, the N-Br bond is polarized. The bromine carries a partially positive charge and can easily be split off. Therefore, NBS is widely used in organic chemistry.

use

There are essentially three applications described in the specialist literature:

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 addition with the associated alkenes or with the aromatics with nuclear substitution .

oxidation

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 oxidized in very good yields, preferably 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 the starting materials for the important Reformatzki reaction .

Numerous other uses are described in the literature.

literature

Review: Virgil, SC in Encyclopedia of Reagents for Organic Synthesis, Ed .: Paquette , LA, Wiley, New York 1995, 1, p. 768.
Canibano, V .; et al .: Synthesis 2175 (2001).
Review: Jeffrey B. Arterburn: Selective oxidation of secondary alcohols . In: Tetrahedron . tape 57 , no. 49 , December 2001, p. 9765-9788 , doi : 10.1016 / S0040-4020 (01) 01009-2 .
Kamal, A., Chouhan, G .: Synlett 474 (2002).
Fieser & Fieser, Reagents for Organic Synthesis 12, p. 79.

Individual evidence

↑ ^a ^b ^c Entry on N-bromosuccinimide. In: Römpp Online . Georg Thieme Verlag, accessed on May 21, 2014.
↑ ^a ^b ^c ^d ^e Entry on N-bromosuccinimide in the GESTIS substance database of the IFA , accessed on February 13, 2017(JavaScript required) .
↑ Registration dossier on N-bromosuccinimide ( Vapor pressure section ) at the European Chemicals Agency (ECHA), accessed on June 13, 2017.

↑ David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Standard Thermodynamic Properties of Chemical Substances, pp. 5-25.

↑ Sumio Shimizu, Yoshiaki Imamura, and Tatsuo Ueki: Incompatibilities between N-Bromosuccinimide and Solvents in Org. Process Res. Dev. 18 (2014) 354-358, doi : 10.1021 / op400360k .

[roempp-1] Entry on N-bromosuccinimide. In: Römpp Online . Georg Thieme Verlag, accessed on May 21, 2014.

[GESTIS-2] Entry on N-bromosuccinimide in the GESTIS substance database of the IFA , accessed on February 13, 2017(JavaScript required) .

[3] Registration dossier on N-bromosuccinimide ( Vapor pressure section ) at the European Chemicals Agency (ECHA), accessed on June 13, 2017.

[CRC90_5_25-4] David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Standard Thermodynamic Properties of Chemical Substances, pp. 5-25.

[Shimizu-5] Sumio Shimizu, Yoshiaki Imamura, and Tatsuo Ueki: Incompatibilities between N-Bromosuccinimide and Solvents in Org. Process Res. Dev. 18 (2014) 354-358, doi : 10.1021 / op400360k .