Question

Which of the following group(s) of reagents is/are used n the above conversion?

• A. (A) $\Rightarrow AcidicKMn{O}_4,\left(B\right)\Rightarrow Ca(OH{)}_2$, (C) $\Rightarrow Zn-Hg/HCl$
• B. (A) $\Rightarrow O_3/P{h}_{3}P,$, (B) $\Rightarrow Ba(OH{)}_2$, (C) $\Rightarrow$ LAH / ether
• C. (A) $\Rightarrow O_3/H_{2}O,$ (B) $\Rightarrow Sr(OH{)}_2,$ (C) $\Rightarrow N{H}_{2}N{H}_2/O^{\ominus }H$
• D. (A) $\Rightarrow O_3/A{g}_{2}O$, (B) $\Rightarrow Ba(OH{)}_2$, (C) $\Rightarrow HI+RedP$

Answer 1

The correct option is A (A) $\Rightarrow AcidicKMn{O}_4,\left(B\right)\Rightarrow Ca(OH{)}_2$, (C) $\Rightarrow Zn-Hg/HCl$

The reagents used in the conversion are represented by the option (A).

The $C=C$ double bond of cyclopentene is cleaved with acidic potassium permanganate to form pentandioic acid. When pentandioic acid is heated with calcium hydroxide, cyclopentanone is obtained. The carbonyl group is then reduced to methylene group by reduction with zinc amalgam and conc $HCl$. This is an example of Clemmenses reduction.