Question

Arrange methylamine, dimethylamine and trimethylamine in increasing order of basicity. Explain the proposed order.​

Answer 1

Answer:

Solution :

Basic character of amines :

→ Amines are basic in nature due to the presence of lone pairs of electrons on nitrogen atom.

➡ Aliphatic amines are stronger bases than ammonia due to +I effect of alkyl groups present in amines.

→ Aromatic amines are weaker bases than ammonia due to -I effect of aryl group.

→ Besides inductive effect, there ate other effects like steric effect, solvation effect, resonance effect which effect the basic strength of amines.

Basicity x +I effect -I effect

Final answer,

* Aniline < Methylamine < Dimethylamine < Trimethylamine *

Answer 2

Answer:

Aliphatic amines are more basic than aromatic amine due to presence of alkyl groups which increase the electron density on nitrogen atom.

In aromatic amine, electron pair of nitrogen undergoes delocalization and hence less available to donate, so, less basic.

More is the alkyl group, more is the electron density and hence more basic. So, Dimethylamine is more basic than Methylamine.

In N− methyl aniline, there is one alkyl group is present. So more basic than aniline.