Chemical elements
  Carbon
    Isotopes
    Energy
    Production
    Application
    Physical Properties
    Chemical Properties
      Methane
      Ethylene
      Acetylene
      Coal-Gas
      Carbon Tetrafluoride
      Tetrafluoromethane
      Carbon Tetrachloride
      Tetrachloromethane
      Carbon Tetrabromide
      Tetrabromomethane
      Carbon Tetraiodide
      Tetraiodomethane
      Carbon Oxychloride
      Carbonyl Chloride
      Phosgene
      Carbon Oxybromide
      Carbonyl Bromide
      Carbon Suboxide
      Carbon Monoxide
      Carbon Dioxide
      Percarbonic Acid
      Carbamic Acid
      Carbamide
      Urea
      Carbon Disulphide
      Carbonyl Sulphide
      Carbon Oxysulphide
      Thiocarbonyl Chloride
      Thiocarbonic Acid
      Thiocarbamic acid
      Thiourea
      Thiocarbamide
      Perthiocarbonates
      Carbon Monosulphide
      Carbon Subsulphide
      Carbon Sulphidoselenide
      Carbon Sulphidotelluride
      Carbon Nitrides
      Cyanogen
      Dicyanogen
      Hydrocyanic Acid
      Prussic Acid
      Cyanogen Chloride
      Chlorocyanogen
      Cyanogen Bromide
      Bromocyanogen
      Cyanogen Iodide
      Iodocyanogen
      Polymerised Cyanogen Halides
      Cyanamide
      Cyanic Acid
      Cyanuric Acid
      Cyamelide
      Fulminic Acid
      Thiocyanic Acid
      Sulphocyanic Acid
      Isoperthiocyanic Acid
      Cyanogen Sulphide
      Thiocyanic Anhydride
    Diamonds
    Graphite
    Amorphous Carbon
    Coal

Cyanogen Bromide, CNBr






Cyanogen Bromide (Bromocyanogen), CNBr, resembles Cyanogen Chloride, CNCl in its manner of preparation, being formed by the action of bromine on hydrocyanic acid or a cyanide. It forms transparent prisms by sublimation, which pass into a cubical form; it melts at 52° C., and boils at 61.3° C.; its vapour density is 3.607; it is poisonous, and its vapour is pungent and affects the eyes. The heat of formation of CNBr from its elements is -37,000 calories, and from (CN)2 and Br2 +40,000 calories. It easily polymerises to (CNBr)3.

In dilute aqueous solution cyanogen bromide shows no evidence of ionisation. Hydrogen sulphide reacts quantitatively with it, thus:

CN-Br + H2S = HCN + HBr + S;

and the following reactions are also characteristic:

2KOH + CNBr = KBr + KCNO + H2O
Na2SO3 + CNBr + H2O = NaBr + NaCN + H2SO4
HI + CNBr = IBr + HCN; IBr + HI = HBr + I2
K2S + CNBr = KBr + KSCN.

A theory of the mechanism of these reactions is given by Dixon and Taylor.


© Copyright 2008-2012 by atomistry.com