Pure amines cannot be prepared by ammonolysis. Why ?

Explanation

The ammonolysis of alkyl halides give a mixture of amines. Ammonia with lone pair of electrons attack the alkyl halide, gives `1^@` - amines. As `1^@` - amines have a line pair of electrons, it attacks again an alkyl halide molecule and gives `2^@`-amines. This reaction will go on until the quaternary ammonium salts are formed.
Now, to separate this mixture of amines is a hard task. Hence pure amines cannot be prepared. The ammonolysis of alkyl halides can be shown below.