Question

Arrange the following compounds in the correct order of basicity.

• A. $a>b>d>c$
• B. $a>c>b>d$
• C. $c>a>d>b$
• D. $b>c>d>a$

Answer 1

Answer: (B)

Nitrogen in structure $a$ and $c$ is $s{p}^3$ hybridised whereas, in structure $b$ and $d$ is $s{p}^2$ hybridised. $d$ is less basic because lone pair participate in conjugation.
Whenever lone pair participates in resonance, it is less available for donation hence it decreases the basicity of compound.
Lone pair present at $s{p}^3$ hybridized nitrogen will be more available as compared to the lone pair present at $s{p}^2.$