MHTCET 16 Apr 2026 Shift 2 Paper

Concept:Benzene is converted into benzaldehyde by introducing a formyl group $-\mathrm{CHO}$ using carbon monoxide and hydrogen chloride.Explanation:The given reaction shows benzene changing into benzaldehyde.Benzene reacts with carbon monoxide $\mathrm{CO}$ and hydrogen chloride $\mathrm{HCl}$ in the presence of anhydrous aluminium chloride $\mathrm{AlCl}_3$ under high pressure.A formyl group $-\mathrm{CHO}$ is introduced directly into the benzene ring.Hence, benzene is converted to benzaldehyde.This process is known as the Gatterman-Koch formylation reaction.The other given options are different reactions.The Etard reaction converts toluene into benzaldehyde using chromyl chloride $\mathrm{CrO}_2\mathrm{Cl}_2$.The Stephen reaction converts nitriles into aldehydes using stannous chloride $\mathrm{SnCl}_2$ and $\mathrm{HCl}$, followed by hydrolysis.The Rosenmund reaction converts acid chlorides into aldehydes using palladium on barium sulphate $\mathrm{Pd}/\mathrm{BaSO}_4$.Therefore, the correct name of the given reaction is the Gatterman-Koch formylation reaction.Answer:Option B - Gatterman-Koch formylation reaction.