Q.Write the following reactions :

Clemmensen reduction converts a carbonyl (aldehyde/ketone) directly to a methylene ($-CH_2-$) group with $Zn(Hg)$/conc. HCl; the Perkin reaction condenses an aromatic aldehyde with an aliphatic acid anhydride, using the sodium salt of the same acid as catalyst, to build a cinnamic-acid-type $\alpha,\beta$-unsaturated acid.

1. Clemmensen reduction An aldehyde or ketone is refluxed with zinc amalgam, $Zn(Hg)$, and concentrated hydrochloric acid. The carbonyl oxygen is completely removed and replaced by two hydrogen atoms, so $C=O$ is converted straight to $CH_2$: $R_2C=O \xrightarrow[conc.\,HCl,\ \Delta]{Zn(Hg)} R_2CH_2 + H_2O$ Example — acetophenone is reduced to ethylbenzene: $C_6H_5COCH_3 \xrightarrow[conc.\,HCl]{Zn(Hg)} C_6H_5CH_2CH_3$ Because the reagent is strongly acidic, Clemmensen reduction is used only for substrates that are stable under acidic conditions; acid-sensitive molecules are instead reduced by the base-catalysed Wolff–Kishner method (hydrazine/KOH).
2. Perkin reaction …