Question

Aliphatic amines are less basic than ammonia and aromatic amines are more basic than ammonia

Answer 1

in amines, there is a lone pair of electrons on nitrogen. The tendency of nitrogen to share these electrons with acids is responsible for the basic character of amines.

n amines, there is a lone pair of electrons on nitrogen. The tendency of nitrogen to share these electrons with acids is responsible for the basic character of amines.It is because in aniline or other aromatic amines, the -NH2 group is attached directly tothe benzene ring. It results in the unshared electron pair on nitrogen atom to be in conjugation with the benzene ring and thus makingit less available for protonation.The lone pair of electrons on nitrogen is withdrawn from it and is being partially shared with the benzene ring, in aromatic amines. Thus, in aromatic amines the electron donating capacity of nitrogen for protonation is considerably decreased as compared to that of ammonia and aliphatic amines. Hence aromatic amines are weaker bases than aliphatic amines and ammonia.

Answer 2

Aliphatic amines are more basic than ammonia and aromatic amines are less basic than ammonia.

• The electron-donating tendency of a nitrogen atom defines its basic nature. As the electron-donating tendency increases its basicity increases.
• Aliphatic amines have an electron donating group attached to the nitrogen which increases the electron density in the nitrogen atom and basicity increases.
• Aromatic amines undergo conjugation with lone pair electrons of nitrogen which decreases the electron density in the nitrogen atom and basicity decreases.