Chemical elements
    Physical Properties
    Chemical Properties
      Carbon Tetrafluoride
      Carbon Tetrachloride
      Carbon Tetrabromide
      Carbon Tetraiodide
      Carbon Oxychloride
      Carbonyl Chloride
      Carbon Oxybromide
      Carbonyl Bromide
      Carbon Suboxide
      Carbon Monoxide
      Carbon Dioxide
      Percarbonic Acid
      Carbamic Acid
      Carbon Disulphide
      Carbonyl Sulphide
      Carbon Oxysulphide
      Thiocarbonyl Chloride
      Thiocarbonic Acid
      Thiocarbamic acid
      Carbon Monosulphide
      Carbon Subsulphide
      Carbon Sulphidoselenide
      Carbon Sulphidotelluride
      Carbon Nitrides
      Hydrocyanic Acid
      Prussic Acid
      Cyanogen Chloride
      Cyanogen Bromide
      Cyanogen Iodide
      Polymerised Cyanogen Halides
      Cyanic Acid
      Cyanuric Acid
      Fulminic Acid
      Thiocyanic Acid
      Sulphocyanic Acid
      Isoperthiocyanic Acid
      Cyanogen Sulphide
      Thiocyanic Anhydride
    Amorphous Carbon

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.

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