This reaction is the basis for the separation of amines from
the non basic organic compounds insoluble in water The reaction of amines with mineral acids to form ammonium salts
shows that these are basic in nature Amines have an unshared pair
of electrons on nitrogen atom due to which they behave as Lewis base Basic character of amines can be better understood in terms of their Kb
and pKb values as explained below:
K = 


3
2
2
R
OH
R
H
NH
NH
O



 







2
or
K[H O]
= 


3
2
O
H
N H
H
R
R
N



 







or
Kb
=


3
2
O
N H
NH
H
R
R



 







pKb = –log Kb
Larger the value of Kb or smaller the value of pKb, stronger is the
base