JEE Advanced Chemistry Question (2023) — Solution

Step-by-step solution

Toluene is formed in the Friedel Craft's reaction, which is the reactant in Etard reaction. The Etard reaction is a chemical reaction that involves the direct oxidation of an aromatic or heterocyclic bound methyl group to an aldehyde using chromyl chloride.  Aniline on diazotization reaction gives benzene diazonium salt, which is the starting material for Gattermann reaction. Gattermann reaction is used for obtaining chlorobenzene or bromobenzene from benzenediazonium chloride by treating it with Cu / HCl   or   Cu / HBr respectively. Phenol gives benzene on reaction with zinc dust, which is the starting material for Gattermann-Koch reaction. The Gattermann-Koch reaction may simply be defined as a chemical transformation in which aromatic compounds are formylated by a mixture of carbon monoxide and hydrogen chloride in the presence of a Lewis acid catalyst such as  AlCl 3 . Toluene on oxidation with potassium permanganate in basic medium gives benzoic acid. The benzoic acid on reaction with thionyl chloride gives benzoyl chloride. The acid chloride formed is the starting material for the Rosenmund reduction. The Rosenmund reduction is a hydrogenation process in which an acyl chloride is selectively reduced to an aldehyde.