Q38 / 180 · COMEDK 2025 (10 May Shift 2) · Chemistry
An organic compound $\mathrm{A}\left(\mathrm{C}_5 \mathrm{H}_9 \mathrm{~N}\right)$ upon reaction with $\mathrm{Na} / \mathrm{Hg} / \mathrm{C}_2 \mathrm{H}_5 \mathrm{OH}$ gives compound B . B reacts with $\mathrm{NaNO}_2 / \mathrm{HCl}$ at 274 K to form C with quantitative liberation of $\mathrm{N}_2$ gas. B also reacts with Hinsberg's reagent to form a compound which is soluble in alkali. Identify compound B.
- A$\mathrm{CH}_3-\left(\mathrm{CH}_2\right)_2-\mathrm{N}-\left(\mathrm{CH}_3\right)_2$
- B$\mathrm{CH}_3-\left(\mathrm{CH}_2\right)_3-\mathrm{NH}-\mathrm{CH}_3$
- Correct answerC$\mathrm{CH}_3-\left(\mathrm{CH}_2\right)_4-\mathrm{NH}_2$
- D$\left[\left(\mathrm{CH}_3\right)_3-\mathrm{N}-\mathrm{CH}_2 \mathrm{CH}_3\right]^{+}$
Solution
Two key reactions of B:
1. Reacts with $NaNO_2/HCl$ at 274 K to liberate $N_2$ quantitatively $\Rightarrow$ characteristic of a primary aliphatic amine ($R-NH_2 + HNO_2 \rightarrow R-OH + N_2\uparrow + H_2O$)
2. Reacts with Hinsberg's reagent to form a product soluble in alkali $\Rightarrow$ confirms primary amine (secondary amines give alkali-insoluble product; tertiary amines do not react).
Among the options, only option (3) $CH_3-(CH_2)_4-NH_2$ is a primary amine. Options (1) and (2) are tertiary and secondary amines respectively, and option (4) is a quaternary ammonium ion.
B is $CH_3-(CH_2)_4-NH_2$
1. Reacts with $NaNO_2/HCl$ at 274 K to liberate $N_2$ quantitatively $\Rightarrow$ characteristic of a primary aliphatic amine ($R-NH_2 + HNO_2 \rightarrow R-OH + N_2\uparrow + H_2O$)
2. Reacts with Hinsberg's reagent to form a product soluble in alkali $\Rightarrow$ confirms primary amine (secondary amines give alkali-insoluble product; tertiary amines do not react).
Among the options, only option (3) $CH_3-(CH_2)_4-NH_2$ is a primary amine. Options (1) and (2) are tertiary and secondary amines respectively, and option (4) is a quaternary ammonium ion.
B is $CH_3-(CH_2)_4-NH_2$
Hence, the correct answer is option: 'C'.