Phenol is heated with phthalic anhydride in presence of conc. H_2SO_4 to give phenolphthalein, which gives pink colour with alkali.

JEE Main Chemistry question

Phenol is heated with phthalic anhydride in presence of conc. to give phenolphthalein, which gives pink colour with alkali.

(A)PhenolphthaleinCorrect
(B)Bakelite
(C)Salicylic acid
(D)Fluorescein

Answer: (A)

Solution

Two molecules of phenol condense with phthalic anhydride under acid catalysis to give phenolphthalein; in alkaline medium the lactone ring opens and both phenolic oxygens ionise, generating an

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Question ID VK-148670