JEE Main · 2026 · 22 Jan 2026 · Shift 2 · Aldehydes Ketones and Carboxylic Acids

A single product in a crossed aldol condensation with acetophenone requires compound A to be an aldehyde having no $\alpha$-hydrogen, so that it can act only as the carbonyl partner and cannot self-condense. Formation of a substituted benzyl alcohol on treatment with concentrated $\mathrm{NaOH}$ is a Cannizzaro reaction, which again needs an aromatic aldehyde without $\alpha$-hydrogen. The formula ${\mathrm{C}}_8{\mathrm{H}}_8{\mathrm{O}}_2$ meeting these conditions corresponds to an aromatic aldehyde carrying a methoxy group, whose Cannizzaro reaction furnishes a methoxy-substituted benzyl alcohol. Compound A is 4-methoxybenzaldehyde.