JEE Main Chemistry question

A nitro-hydroxybenzaldehyde + CH₂(COOC₂H₅)₂ --C₂H₅O⁻--> --H₂O, H⁺--> X [Aromatic]. Identify the final product X.

(A)A coumarin-type lactone (2H-chromen-2-one bearing the nitro substituent)Correct
(B)An open-chain cinnamic-ester product (no cyclization)
(C)An open-chain diacid
(D)A simple Knoevenagel adduct, uncyclized

Answer: (A)

Solution

This is the classic Knoevenagel–Doebner-type route to coumarins: a salicylaldehyde-type substrate (ortho-hydroxybenzaldehyde, here nitro-substituted) condenses with diethyl malonate (base-catalyzed Knoevenagel condensation at the

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Question ID VK-149393