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Cyanogen bromide

Cyanogen bromide
Skeletal formula of cyanogen bromide
Spacefill model of cyanogen bromide
Names
Preferred IUPAC name
Carbononitridic bromide
Other names
  • Bromine cyanide
  • Campilit
Identifiers
506-68-3 YesY
3D model (Jmol) Interactive image
1697296
ChemSpider 10044 YesY
ECHA InfoCard 100.007.320
EC Number 208-051-2
MeSH Cyanogen+Bromide
PubChem 10476
RTECS number GT2100000
UN number 1889
Properties
BrCN
Molar mass 105.921 g mol1−
Appearance Colorless solid
Density 2.015 g mL−1
Melting point 50 to 53 °C (122 to 127 °F; 323 to 326 K)
Boiling point 61 to 62 °C (142 to 144 °F; 334 to 335 K)
Reacts
Vapor pressure 16.2 kPa
Thermochemistry
136.1–144.7 kJ mol−1
Hazards
GHS pictograms The corrosion pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS) The skull-and-crossbones pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS) The environment pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)
GHS signal word DANGER
H300, H310, H314, H330, H410
P260, P273, P280, P284, P302+350
Very Toxic T+ Dangerous for the Environment (Nature) N
R-phrases R26/27/28, R34, R50/53
S-phrases S36/37/39, S45
NFPA 704
Flammability code 0: Will not burn. E.g., water Health code 4: Very short exposure could cause death or major residual injury. E.g., VX gas Reactivity code 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g., calcium Special hazards (white): no codeNFPA 704 four-colored diamond
US health exposure limits (NIOSH):
PEL (Permissible)
 5 mg m−3
Related compounds
Related alkanenitriles
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
YesY  (what is YesYN ?)
Infobox references

Cyanogen bromide is the inorganic compound with the formula (CN)Br, also met as BrCN. It is a colorless solid that is widely used to modify biopolymers, fragment proteins and peptides, and synthesize other compounds. The compound is classified as a pseudohalogen.

The carbon atom in cyanogen bromide is bonded to bromine by a single bond and to nitrogen by a triple bond (i.e. Br–C≡N). The compound is linear and polar, but it does not spontaneously ionize in water. It dissolves in both water and polar organic solvents.

Cyanogen bromide can be prepared by oxidation of sodium cyanide with bromine, which proceeds in two steps via the intermediate cyanogen ((CN)2):

When refrigerated the material has an extended shelflife. Like some other cyanogen compounds cyanogen bromide undergo an exothermic trimerisation to cyanuric bromide ((BrCN)3). This reaction is catalyzed by traces of bromine, metal salts, acids and bases. For this reason, experimentalists avoid brownish samples.

Cyanogen bromide is hydrolyzed to release hydrogen cyanide and hypobromous acid

The main uses of cyanogen bromide are to immobilize proteins, fragment proteins by cleaving peptide bonds, and synthesize cyanamides and other molecules.

Cyanogen bromide is often used to immobilize proteins by coupling them to reagents such as agarose for affinity chromatography. Because of its simplicity and mild pH conditions, cyanogen bromide activation is the most common method for preparing affinity gels. Cyanogen bromide is also often used because it reacts with the hydroxyl groups on agarose to form cyanate esters and imidocarbonates. These groups are reacted with primary amines in order to couple the protein onto the agarose matrix, as shown in the figure. Because cyanate esters are more reactive than are cyclic imidocarbonates, the amine will react mostly with the ester, yielding isourea derivatives, and partially with the less reactive imidocarbonate, yielding substituted imidocarbonates.


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