(N/A) In the Clemmensen reduction reaction,the carbonyl group $(>C=O)$ of aldehydes and ketones is reduced to a methylene group $(-CH_{2}-)$ upon treatment with zinc amalgam $(Zn-Hg)$ and concentrated hydrochloric acid $(HCl)$.
General reaction:
$>C=O + 4[H] \xrightarrow{Zn-Hg, \text{Conc. } HCl} >CH_{2} + H_{2}O$
Examples:
$(i)$ $CH_{3}CHO + 4[H] \xrightarrow{Zn-Hg, \text{Conc. } HCl} CH_{3}CH_{3} + H_{2}O$ (Ethanal to Ethane)
(ii) $CH_{3}COCH_{3} + 4[H] \xrightarrow{Zn-Hg, \text{Conc. } HCl} CH_{3}CH_{2}CH_{3} + H_{2}O$ (Propanone to Propane)
(iii) $C_{6}H_{5}COCH_{3} + 4[H] \xrightarrow{Zn-Hg, \text{Conc. } HCl} C_{6}H_{5}CH_{2}CH_{3} + H_{2}O$ (Acetophenone to Ethylbenzene)