Cyanogen Bromide (CNBr)

Introduction

Cyanamides are versatile synthons that can be transformed into many biologically active compounds such as ureas, thioureas, selenoureas, guanidines, hydroxy­guanidines, creatine, and a large number of heterocyclic compounds. Cyanogen bromide is a very useful and extensively used reagent for the synthesis of cyanamides. It is a colorless or white crystalline solid that decomposes in the presence of moisture and has a very small liquid range (mp 50-53 °C, bp 61-62 °C). It is cheap and can be ­obtained commercially, or it can be synthesized by the ­reaction of sodium cyanide with bromine in aqueous ­medium. [1] Caution! It is highly toxic. Reactions should be carried out in a well-ventilated hood.

CNBr produces electrophilic cyanide. Therefore, it is ­attacked by nucleophiles such as amines, alcohols and ­thiols. Organic chemists are fully utilizing this property of the reagent. CNBr has also been applied in molecular ­biology to digest some proteins, and as a coupling agent for phosphoramidate or pyrophosphate internucleotide bonds in DNA duplexes.

References

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