In Reimer - Tiemann reaction, phenol is converted into salicylaldehyde through an intermediate. The structure of intermediate is .
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Answer
(2) [figure]
Solution
CHCl3 NaOH :CCl2 (dichlorocarbene, electrophile); phenol NaOH sodium phenoxide
∵ the phenoxide ring is strongly activated, :CCl2 attacks the ortho position ⇒ o-dichloromethyl phenoxide (intermediate):
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∴ hydrolysis of –CHCl2 by NaOH gives –CHO; acidification gives salicylaldehyde.
Answer: (2)