Question

Which among the following compound is the strongest base?

• A. ${\mathrm{C}}_6{\mathrm{H}}_5{\mathrm{NH}}_2$
• B. ${\mathrm{C}}_6{\mathrm{H}}_5{\mathrm{CH}}_2{\mathrm{NH}}_2$
• C. $\mathrm{p}-{\mathrm{NO}}_2{\mathrm{C}}_6{\mathrm{H}}_4{\mathrm{NH}}_2$
• D. $\mathrm{m}-{\mathrm{NO}}_2{\mathrm{C}}_6{\mathrm{H}}_4{\mathrm{NH}}_2$

Answer 1

The correct option is B

${\mathrm{C}}_6{\mathrm{H}}_5{\mathrm{CH}}_2{\mathrm{NH}}_2$

The explanation for the correct option

(B)${\mathrm{C}}_6{\mathrm{H}}_5{\mathrm{CH}}_2{\mathrm{NH}}_2$

Basicity

• Amines act as bases due to the lone pair of electrons on them.
• Benzylamine$\left({\mathrm{C}}_6{\mathrm{H}}_5{\mathrm{CH}}_2{\mathrm{NH}}_2\right)$ is the strongest base among all because the aliphatic amines are more basic than aromatic amines.
• An aliphatic amine, ${\mathrm{NH}}_2$ group is connected to an alkyl group.
• An alkyl group is an electron-donating group. So, the lone pair of electrons on nitrogen is readily available.

The explanation for the incorrect option

• Aniline$\left({\mathrm{C}}_6{\mathrm{H}}_5{\mathrm{NH}}_2\right)$, the lone pair of nitrogen atoms conjugation with the π-electrons of the benzene ring and thus, takes part in resonance.
• EWG $(-{\mathrm{NO}}_2)$ at o, p, and m-positions decreases the basic character because it is an electron-withdrawing group.
• Hence, options (A), (C),and (D) are incorrect.

Hence, option (B) is correct. ${\mathrm{C}}_6{\mathrm{H}}_5{\mathrm{CH}}_2{\mathrm{NH}}_2$ is the strongest base.