Reaction of phenol with chloroform in presence of dilute sodium hydroxide finally introduces which one of the following functional group?
- -COOH
- -CHCl2
- -CHO
- -CH2Cl
Answer
(3) -CHO
Solution
This is the Reimer–Tiemann reaction. As per NCERT, on treating phenol with chloroform in the presence of sodium hydroxide, a -CHO group is introduced at the ortho position of the benzene ring.
The intermediate substituted benzal chloride (-CHCl2) is hydrolysed by the alkali ⇒ -CHO; acidification gives salicylaldehyde.
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Answer: (3)