An organic compound 'A' on reaction with NH₃ followed by heating gives compound B. Which on further strong heating gives compound C (C₈H₅NO₂). Compound C on sequential reaction with ethanolic KOH, alkyl chloride and hydrolysis with alkali gives a primary amine. The compound A is:
(A)(see structure)
(B)(see structure)
(C)(see structure)✓ Correct
(D)(see structure)
Answer: (C)
Solution
This is the Gabriel phthalimide synthesis for preparing primary amines. Compound C with molecular formula C₈H₅NO₂ is phthalimide. Working backward: phthalimide is formed by heating phthalamic acid (compound B), which in turn is formed by the reaction of phthalic anhydride with NH₃. Therefore, compound A must be phthalic anhydride, which is formed from phthalic acid (option C) by heating. The sequence is: phthalic acid → (heat) → phthalic anhydride (A) → (NH₃, heat) → phthalamic acid (B) → (strong heat) → phthalimide (C). The phthalimide then undergoes the Gabriel synthesis (KOH/EtOH, RX, then hydrolysis) to give a primary amine.
JEE Main · 2022 · 25 Jul 2022 · Shift 1 · Single correct option
