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 The pKb values of few amines are given in Table 9 3 pKb value of ammonia is 4