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N-Bromosuccinimide

N-Bromosuccinimide orNBS is achemical reagent used inradical substitution,electrophilic addition, andelectrophilic substitutionreactions inorganic chemistry. NBS can be a convenient source of Br•, thebromine radical.[1]

N-Bromosuccinimide
Skeletal formula of N-bromosuccinimide
Space-filling model of the N-bromosuccinimide molecule
Names
Preferred IUPAC name
1-Bromopyrrolidine-2,5-dione
Other names
N-bromosuccinimide; NBS
Identifiers
3D model (JSmol)
113916
ChEBI
ChemSpider
ECHA InfoCard100.004.435Edit this at Wikidata
EC Number
  • 204-877-2
26634
UNII
  • InChI=1S/C4H4BrNO2/c5-6-3(7)1-2-4(6)8/h1-2H2 checkY
    Key: PCLIMKBDDGJMGD-UHFFFAOYSA-N checkY
  • InChI=1/C4H4BrNO2/c5-6-3(7)1-2-4(6)8/h1-2H2
    Key: PCLIMKBDDGJMGD-UHFFFAOYAS
  • BrN1C(=O)CCC1=O
Properties
C4H4BrNO2
Molar mass177.985 g·mol−1
AppearanceWhite solid
Density2.098 g/cm3 (solid)
Melting point175 to 178 °C (347 to 352 °F; 448 to 451 K)
Boiling point339 °C (642 °F; 612 K)
14.7 g/L (25 °C)
Solubility in CCl4Insoluble (25 °C)
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
Irritant
Safety data sheet (SDS)[1]
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa).
checkY verify (what is checkY☒N ?)

Preparation

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NBS is commercially available. It can also be synthesized in the laboratory. To do so,sodium hydroxide and bromine are added to an ice-water solution ofsuccinimide. The NBS productprecipitates and can be collected by filtration.[2]

Crude NBS gives better yield in theWohl–Ziegler reaction. In other cases, impure NBS (slightly yellow in color) may give unreliable results. It can be purified by recrystallization from 90 to 95 °C water (10 g of NBS for 100 mL of water).[1]

Reactions

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Addition to alkenes

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NBS reacts with alkenes in aqueous solvents to givebromohydrins. The preferred conditions are the portionwise addition of NBS to a solution of the alkene in 50% aqueousDMSO,DME,THF, ortert-butanol at 0 °C.[3] Formation of abromonium ion and immediate attack by water gives strongMarkovnikov addition andanti stereochemical selectivities.[4]

 

Side reactions include the formation of α-bromoketones and dibromo compounds. These can be minimized by the use of freshlyrecrystallized NBS.

With the addition ofnucleophiles, instead ofwater, various bifunctional alkanes can be synthesized.[5]

 

Allylic and benzylic bromination

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Standard conditions for using NBS in allylic and/or benzylicbromination involves refluxing a solution of NBS inanhydrousCCl4 with a radical initiator—usually azobisisobutyronitrile (AIBN) orbenzoyl peroxide, irradiation, or both to effectradicalinitiation.[1][6] The allylic and benzylic radical intermediates formed during this reaction are more stable than other carbon radicals and the major products are allylic and benzylic bromides. This is also called theWohl–Ziegler reaction.[7][8]

 

Thecarbon tetrachloride must be maintained anhydrous throughout the reaction, as the presence ofwater may likelyhydrolyze the desired product.[9]Barium carbonate is often added to maintain anhydrous and acid-free conditions.

In the above reaction, while a mixture of isomeric allylic bromide products are possible, only one is created due to the greater stability of the 4-position radical over the methyl-centered radical.

Bromination of carbonyl derivatives

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NBS can α-brominate carbonyl derivatives via either a radical pathway (as above) or via acid-catalysis. For example,hexanoyl chloride1 can be brominated in the alpha-position by NBS using acid catalysis.[10]

 

The reaction ofenolates,enol ethers, orenol acetates with NBS is the preferred method of α-bromination as it is high-yielding with few side-products.[11][12]

Bromination of aromatic derivatives

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Electron-richaromatic compounds, such asphenols,anilines, and various aromaticheterocycles,[13] can be brominated using NBS.[14][15] UsingDMF as the solvent gives high levels of para-selectivity.[16]

Hofmann rearrangement

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NBS, in the presence of a strong base, such asDBU, reacts with primaryamides to produce acarbamate via theHofmann rearrangement.[17]

 

Selective oxidation of alcohols

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It is uncommon, but possible for NBS to oxidize alcohols.E. J. Coreyet al. found that one can selectivelyoxidize secondaryalcohols in the presence of primary alcohols using NBS in aqueousdimethoxyethane (DME).[18]

 

Oxidative decarboxylation of α-amino acids

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NBS electrophilically brominates the amine, which is followed by decarboxylation and release of an imine. Further hydrolysis will yield an aldehyde and ammonia.[19][20] (cf. non-oxidative PLP dependent decarboxylation)

 

Precautions

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NBS is a weaker equivalent to bromine in its dangers. NBS is typically stored in a refrigerator. Pure NBS is white, but it is often found to be off-white or brown colored by bromine.

Some reactions involving NBS are exothermic, requiring suitable precautions.

See also

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References

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  1. ^abcVirgil, Scott C.; Jenkins, P. R.; Wilson, A. J.; García Romero, M. D. (2006). "N -Bromosuccinimide".Encyclopedia of Reagents for Organic Synthesis.doi:10.1002/047084289X.rb318.pub2.ISBN 0-471-93623-5.
  2. ^Ziegler, K.; Späth, A. (1942). "Die Halogenierung ungesättigter Substanzen in der Allylstellungs".Ann. Chem.551 (1):80–119.doi:10.1002/jlac.19425510103.
  3. ^Hanzlik, R. P."Selective epoxidation of terminal double bonds".Organic Syntheses;Collected Volumes, vol. 6, p. 560.
  4. ^Beger, J. (1991). "Präparative Aspekte elektrophiler Dreikomponentenreaktionen mit Alkenen" [Preparative aspects of electrophilic three-component reactions with alkenes].J. Prakt. Chem.333 (5):677–698.doi:10.1002/prac.19913330502.
  5. ^Haufe, G.; Alvernhe, G.; Laurent, A.; Ernet, T.; Goj, O.; Kröger, S.; Sattler, A. (2004)."Bromofluorination of alkenes".Organic Syntheses;Collected Volumes, vol. 10, p. 128.
  6. ^Greenwood, F. L.; Kellert, M. D.; Sedlak, J. (1958). "4-Bromo-2-heptene".Organic Syntheses.38: 8.doi:10.15227/orgsyn.038.0008.
  7. ^Wohl, A. (1919)."Bromierung ungesättigter Verbindungen mitN-Brom-acetamid, ein Beitrag zur Lehre vom Verlauf chemischer Vorgänge" [Bromination of unsaturated compounds withN-bromoacetamide, a contribution to the theory of the course of chemical processes].Berichte der Deutschen Chemischen Gesellschaft (A and B Series).52:51–63.doi:10.1002/cber.19190520109.
  8. ^Ziegler, K.; Schenck, G.; Krockow, E. W.; Siebert, A.; Wenz, A.; Weber, H. (1942). "Die Synthese des Cantharidins" [The synthesis of cantharidin].Justus Liebig's Annalen der Chemie.551:1–79.doi:10.1002/jlac.19425510102.
  9. ^Binkley, R. W.; Goewey, G. S.; Johnston, J. (1984). "Regioselective ring opening of selected benzylidene acetals. A photochemically initiated reaction for partial deprotection of carbohydrates".J. Org. Chem.49 (6): 992.doi:10.1021/jo00180a008.
  10. ^Harpp, D. N.; Bao, L. Q.; Coyle, C.; Gleason, J. G.; Horovitch, S. (1988)."2-Bromohexanoyl chloride".Organic Syntheses;Collected Volumes, vol. 6, p. 190.
  11. ^Stotter, P. L.; Hill, K. A. (1973). "α-Halocarbonyl compounds. II. Position-specific preparation of α-bromoketones by bromination of lithium enolates. Position-specific introduction of α,β-unsaturation into unsymmetrical ketones".J. Org. Chem.38 (14): 2576.doi:10.1021/jo00954a045.
  12. ^Lichtenthaler, F. W. (1992). "Various Glycosyl Donors with a Ketone or Oxime Function next to the Anomeric Centre: Facile Preparation and Evaluation of their Selectivities in Glycosidations".Synthesis.1992:179–84.doi:10.1055/s-1992-34167.
  13. ^Amat, M.; Hadida, S.; Sathyanarayana, S.; Bosc, J. (1998)."Regioselective synthesis of 3-substituted indoles".Organic Syntheses;Collected Volumes, vol. 9, p. 417.
  14. ^Gilow, H. W.; Burton, D. E. (1981). "Bromination and chlorination of pyrrole and some reactive 1-substituted pyrroles".J. Org. Chem.46 (11): 2221.doi:10.1021/jo00324a005.
  15. ^Brown, W. D.; Gouliaev, A. H. (2005)."Synthesis of 5-bromoisoquinoline and 5-bromo-8-nitroisoquinoline".Organic Syntheses.81: 98.
  16. ^Mitchell, R. H.; Lai, Y. H.; Williams, R. V. (1979). "N-Bromosuccinimide-dimethylformamide: a mild, selective nuclear monobromination reagent for reactive aromatic compounds".J. Org. Chem.44 (25): 4733.doi:10.1021/jo00393a066.
  17. ^Keillor, J. W.; Huang, X. (2004)."Methyl carbamate formation via modified Hofmann rearrangement reactions".Organic Syntheses;Collected Volumes, vol. 10, p. 549.
  18. ^Corey, E. J.; Ishiguro, M (1979). "Total synthesis of (±)-2-isocyanopupukeanane".Tetrahedron Lett.20 (30):2745–2748.doi:10.1016/S0040-4039(01)86404-2.
  19. ^Ramachandran, M. S.; Easwaramoorthy, D.; Rajasingh, V.; Vivekanandam, T. S. (1990-01-01)."N-Chlorosuccinimide-Promoted Oxidative Decarboxylation of α-Amino Acids in Aqueous Alkaline Medium".Bulletin of the Chemical Society of Japan.63 (8):2397–2403.doi:10.1246/bcsj.63.2397.
  20. ^Song, Xuezheng; Ju, Hong; Zhao, Chunmei; Lasanajak, Yi (2014-10-15)."Novel Strategy to Release and TagN-Glycans for Functional Glycomics".Bioconjugate Chemistry.25 (10):1881–1887.doi:10.1021/bc500366v.ISSN 1043-1802.PMC 4197647.PMID 25222505.

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