Question

Which of the following orders is correct regarding the basic strength of subsituted aniline ?

• A. p - nitroaniline > p - aminobenzaldehyde > p- bromoaniline
• B. p - nitroaniline < p - bromoaniline < p- aminobenzaldehyde
• C. p - nitroaniline < p - aminobenzaldehyde < p- bromoaniline
• D. p - nitroaniline > p - aminobenzaldehyde < p-bromoaniline

Answer 1

The correct option is C p - nitroaniline < p - aminobenzaldehyde < p- bromoaniline

Nitro group is strong electron withdrawing group.
Hence, p - nitroaniline is least basic.

Halogens and aldehydes are weakly deactivating or weak electron withdrawing groups.

The order of the ability to withdraw electron density is nitro > aldehyde > bromine.

Higher is the ability of the substituent to withdraw electrons, lower is the basicity of amine.

Hence, the order of basicity is
p - nitroaniline < p - amino benzaldehyde < p-bromoaniline.

Option C is correct.