Question

Choose the correct statement(s) related to the basic strength of (a) and (b).

• A. (a) is less basic than (b) due to SIP effect.
• B. (a) is more basic than (b) due to SIR effect
• C. $N{O}_2$ will increase the electron density on N and make them more basic
• D. $N{O}_2$ will decrease the electron density on N and make them less basic.

Answer 1

Answer: (A), (D)

$N{O}_2$ will decrease the electron density on N and make them less basic.

$N{O}_2$ at para position shows -R and -I effect.
In (a) due to SIP effect, conjugate acid formed by (a) will experience steric hindrance due to ortho methyl groups. Therefore, donation of lone pair of electrons by (a) is less favoured.
Hence, (a) is less basic than (b) due to SIP effect.