$[P] \stackrel{\text { Br }_{2}}{\longrightarrow} C_{2} \mathrm{H}_{4}$ Br $_{2} \frac{\text { NaNH…
$[Q] \frac{20 \% \mathrm{H}_{2} \mathrm{SO}_{4}}{\mathrm{Hg}^{2+} \cdot \Delta}[R] \stackrel{\mathrm{Zn}-\mathrm{Hg} / \mathrm{HC}}{\longrightarrow}[S]$
The species $P, Q, R$ and $S$ respectively are
- ethene, ethyne, ethanal, ethane
- ethane, ethyne, ethanal, ethene
- ethene, ethyne, ethanal, ethanol
- ethyne, ethane, ethene, ethanal
Solution
$[P] \stackrel{\mathrm{Br}_{2}}{\longrightarrow} \mathrm{C}_{2} \mathrm{H}_{4} \mathrm{Br}_{2} \frac{\mathrm{NaNH}_{2}}{\mathrm{NH}_{3}},[Q]$
$[Q] \frac{20 \% / \mathrm{H}_{2} \mathrm{SO}_{4}}{\mathrm{Hg}^{2+}, \Delta},[\mathrm{R}] \stackrel{\mathrm{Zn} \cdot \mathrm{Hg} / \mathrm{HG}}{\longrightarrow}[S]$
$[P]$ is an alkene with two carbon atoms i.e. ethene. When it reacts with Br $y$, addition reaction occurs and $\mathrm{C}_{2} \mathrm{H}_{4} \mathrm{Br}_{2}$ is formed.
$\mathrm{C}_{\mathrm{H}}, \mathrm{Br}_{2}$(1, 2-dibromoethane) on reaction with $\operatorname{NaNH}_{2} / \mathrm{NH},$ gives ethyne $(\mathrm{C}, \mathrm{H}, \mathrm{y})$
Ethyne IQlin presence of $20 \% \mathrm{H}_{2} \mathrm{SO}_{4}, \mathrm{Hg}^{2+} \mathrm{at} 333 \mathrm{K}$
gives ethanal.
Ethanal $[R]$ undergoes reduction in presence of $$
\text { Zn-Hg /HCl to give ethane }[S]
$$
$\mathrm{CH}_{3}\mathrm{CHO} \xrightarrow[\mathrm{HCl}]{\mathrm{Zn-Hg}} \mathrm{CH}_{3}-\mathrm{CH}_{3}$
Asked in: JEE-TOPICTESTS-CHEMISTRY
Practice more ALCOHOLS, PHENOLS AND ETHERS questions on Aicharya