The
order of basic strength in case of methyl substituted amines and ethyl
substituted amines in aqueous solution is as follows:
(C2H5)2NH > (C2H5)3N > C2H5NH2 > NH3
(CH3)2NH > CH3NH2 > (CH3)3N > NH3
(b) Arylamines versus ammonia
pKb value of aniline is quite high Why is it so It is because in
aniline or other arylamines, the -NH2 group is attached directly to
the benzene ring It results in the unshared electron pair on nitrogen
atom to be in conjugation with the benzene ring and thus making
it less available for protonation