Which of the following is Wolf-Kishner reduction?

Which of the following is Wolf-Kishner reduction?
  1. $\mathrm{RCOCl} \underset{\mathrm{Pd}-\mathrm{BaSO}_4}{\stackrel{\mathrm{H}_2}{\longrightarrow}} \mathrm{R}-\mathrm{CHO}+\mathrm{HCl}$
  2. $\mathrm{RCN} \underset{\mathrm{SnCl}_2, \mathrm{HCl}}{\longrightarrow} \mathrm{OCHO}+\mathrm{NH}_4 \mathrm{Cl}$
  3. $\mathrm{RCHO} \underset{\Delta}{\stackrel{\mathrm{Zn}-\mathrm{H}_6 \text {.cose.HCl }}{\longrightarrow}} \mathrm{R}-\mathrm{CH}_3+\mathrm{H}_2 \mathrm{O}$
  4. $\mathrm{RCOR} \frac{\mathrm{i} \mathrm{H}_2 \mathrm{~N}-\mathrm{NH}_2, \Delta}{\text { ii) } \mathrm{KOH}, \mathrm{HO}\left(\mathrm{CH}_2\right)_2 \mathrm{OH}} \longrightarrow \mathrm{R}-\mathrm{CH}_2-\mathrm{R}+\mathrm{N}_2$

Solution

The carbonyl group of aldehydes and ketones is reduced to $\mathrm{CH}_2$ group (hydrocarbons) on treatment with hydrazine followed by heating with sodium or potassium hydroxide in high boiling solvent such as ethylene glycol is known as Wolff-Kishner reduction. $\geq \mathrm{c}=\mathrm{O} \xrightarrow[\mathrm{CH}]{2} \mathrm{NH}_2 \mathrm{NNH}_2 \xrightarrow[\text { heat }]{\text { kOH/ethylens glycal }}>\mathrm{CH}_2+\mathrm{N}_2$

Asked in: MHT CET 2023 (13 May Shift 2)

Practice more Hydrocarbons questions on Aicharya