Give plausible explanation for each of the following :
Why are aliphatic amines stronger bases than aromatic amines?
Aliphatic amines are stronger bases than aromatic amines due to following reasons:
(a) Electron pair on the nitrogen atom of aromatic is involved in conjugation with the π-electron pairs of the ring as follows
(b) Anilinium ion obtaines by accepting a proton is less stablisied by resonance.
Due to the −R effect of the benzene ring, the electrons on the N- atom are less available in case of aromatic amines. Therefore, the electrons on the N-atom in aromatic amines cannot be donated easily. So, aniline is a weaker base than alkyl amines, in which +1 effect increases the electron density on the nitrogen atom. This explains why aliphatic amines are stronger bases than aromatic amines.