Name: Basicity of Amine and Its Reactions
Uploaded: 2019-07-19
Duration: 6 min 28 s
Description: Amines are aliphatic and aromatic derivatives of ammonia and are considered weak bases. Let's learn about the basicity of amines and its roles.

Question

Arrange the following in decreasing order of ${pK}_{b}$ values
$C_{6} H_{5} {NH}_{2}, C_{6} H_{5} {NHCH}_{3}, C_{6} H_{5} {CH}_{2} {NH}_{2}, {CH}_{3} {NH}_{2}, {NH}_{3}$

Accepted Answer

Basic character increases with the increase in donation of lone pair of electrons. Aniline is an aromatic amine. In the case of aromatic amine, the lone pair undergoes conjugation with the benzene. As a result, lone pair availability decreases as well as the basicity. Higher is the pKb value, lower is the basic strength of amine.

In aniline, the amino group “ $- {NH}_{2}$ is directly bonded to benzene ring. lone pair of electrons on nitrogen gets involved in resonance of the ring and lone pair aren't available for donation. Hence, they are weaker than ammonia. Alkylamines (methylamine) are stronger bases compared to ammonia because they have an alkyl group attached to them. It donates more electrons to the atom, so that it can give more to act as a base.

So, decreasing order of ${pK}_{b}$ values are as follows:

$C_{6} H_{5} {NH}_{2} > C_{6} H_{5} {NHCH}_{3} > C_{6} H_{5} {CH}_{2} {NH}_{2} > {NH}_{3} > {CH}_{3} {NH}_{2}$ .

Arrange the following in decreasing order of ${pK}_{b}$ values
$C_{6} H_{5} {NH}_{2}, C_{6} H_{5} {NHCH}_{3}, C_{6} H_{5} {CH}_{2} {NH}_{2}, {CH}_{3} {NH}_{2}, {NH}_{3}$

Important Questions on Amines

Learn and Prepare for any exam you want !

Arrange the following in decreasing order of pKb values C6H5NH2,C6H5NHCH3,C6H5CH2NH2,CH3NH2,NH3

Important Questions on Amines

Learn and Prepare for any exam you want !

Arrange the following in decreasing order of ${pK}_{b}$ values
$C_{6} H_{5} {NH}_{2}, C_{6} H_{5} {NHCH}_{3}, C_{6} H_{5} {CH}_{2} {NH}_{2}, {CH}_{3} {NH}_{2}, {NH}_{3}$