JEE Main · 2022 · 28 Jun 2022 · Shift 1 · Compounds Containing Nitrogen

Primary aliphatic amines react with nitrous acid ($\mathrm{HNO}{}_2$, generated in situ from $\mathrm{NaNO}{}_2+\mathrm{HCl}$) to form unstable aliphatic diazonium salts at low temperature (273 K). Unlike aromatic diazonium salts, aliphatic diazonium salts are highly unstable and decompose immediately even at low temperatures. When the temperature is raised to room temperature (298 K), the diazonium salt decomposes to form a carbocation, which then reacts with water to give an alcohol: $\mathrm{R}-\mathrm{NH}{}_2\to \mathrm{R}-\mathrm{N}{}_2{}^{+}\to \mathrm{R}{}^{+}\stackrel{\mathrm{H}{}_2\mathrm{O}}{\to }\mathrm{R}-\mathrm{OH}$.