Structure of Simpler Organic Compounds. 133 



Both these reactions are examples of general reactions of 

 cyanides, and indicate that the chemical constitution of 

 hydrocyanic acid may be represented by the formula 

 H - C i N. 



Potassium cyanide, KCN, is made by various pro- 

 cesses on a large scale, in which the reactions involved 

 are somewhat complex. 



The nitrites or cyanides can be prepared by the action 

 of potassium cyanide on alkyl halogen compounds, for 

 example 



C.HJ + KCN = KI + C,H 5 CN 



or by the distillation of ammonium salts with phosphorus 

 pentoxide 



CH. COONH 4 - 2H 2 = CH 3 CN 



Methyl cyanide is derived thus from acetic acid, and is 

 also designated acetonitrile. 



The two principal reactions are the hydrolysis to car- 

 boxylic acid (see p. 88) and the reduction to primary amines. 



The nitriles are colourless liquids, the lower members 

 of the series being readily soluble in water. 



Cyanates. When potassium cyanide is heated with 

 lead oxide, the latter is readily reduced. For this reason 

 potassium cyanide is largely used as a reducing agent 



The ammonium cyanate readily undergoes isomeric change 

 into urea. The free acid, HO CN, is an unstable sub- 

 stance, which cannot be prepared by a direct method 

 from its salts. 



Isocyanides or Isonitriles. In these substances the 

 nitrogen is directly united to the alkyl radicle. They are 

 prepared by treating amines with chloroform and alcoholic 

 potassium hydroxide (see p. 127) 



3KOH + CHC1 3 = CH 3 -N ; C + 3KC1 + 3H a O 



