Q21 / 180 · KCET 2011 · Chemistry
Identify $B$ and $D$ in the following sequence of reactions.
- Amethanol and bromoethane
- Bethyl hydrogen sulphate and alcoholic $\mathrm{KOH}$
- Cethyl hydrogen sulphate and aqueous $\mathrm{KOH}$
- Correct answerDethanol and alcoholic $\mathrm{KOH}$
Solution
$$
\mathrm{CH}_{2}=\mathrm{CH}_{2} \stackrel{\text { Conc. } \mathrm{H}_{2} \mathrm{SO}_{4}}{\longrightarrow} \mathrm{CH}_{3}-\underset{(A)}-\mathrm{CH}_{2}-\mathrm{HSO}_{4}
$$
(addition reaction)
$\mathrm{CH}_{3}-\mathrm{CH}_{2}-\mathrm{HSO}_{4} \stackrel{\Delta, \mathrm{H}_{2} \mathrm{O}}{\longrightarrow} \mathrm{CH}_{3}-\underset{(B)}{\mathrm{CH}_{2}-\mathrm{OH}}$
(hydrolysis)
$$
\mathrm{CH}_{3}-\mathrm{CH}_{2}-\mathrm{OH} \stackrel{\mathrm{PBr}_{3}}{\longrightarrow} \mathrm{CH}_{3}\underset{(c)}-\mathrm{CH}_{2}-\mathrm{Br}
$$
(bromination)
$\mathrm{CH}_{3}-\mathrm{CH}_{2}-\mathrm{Br} \stackrel{\mathrm{Alc} . \mathrm{KOH}(\Delta)}{(\Delta)} \mathrm{CH}_{2}=\mathrm{CH}_{2}$
(dehydrohalogenation)
Hence, $B$ and $D$ in the above given reactions are $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OH}$ (ethanol) and alc. $\mathrm{KOH}$.
Hence, the correct answer is option: 'D'.