Question:
The major product obtained when Phenol is treated with $\mathrm{CHCl_3}$ and aqueous $\mathrm{NaOH}$ at $340\,K$, followed by acidification is:}
The major product obtained when Phenol is treated with $\mathrm{CHCl_3}$ and aqueous $\mathrm{NaOH}$ at $340\,K$, followed by acidification is:}
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Reimer-Tiemann reaction:
\[
\mathrm{Phenol}
\xrightarrow[\mathrm{CHCl_3}]{\mathrm{NaOH}}
o\text{-Hydroxybenzaldehyde}
\]
Major product = Salicylaldehyde.
Updated On: Jun 17, 2026
- Benzalacetophenone
- Salicylaldehyde
- Salicylic acid
- Anisole
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Verified By Collegedunia
The Correct Option is B
Solution and Explanation
Concept:
Phenol reacts with chloroform and aqueous sodium hydroxide followed by acidification in the Reimer-Tiemann reaction. The reaction introduces a formyl group (\(-CHO\)) mainly at the ortho position of phenol.
Step 1: Formation of dichlorocarbene. Chloroform reacts with aqueous alkali. \[ \mathrm{CHCl_3 + OH^-} \rightarrow :\mathrm{CCl_2} \] Dichlorocarbene is generated.
Step 2: Electrophilic substitution on phenol. The activated aromatic ring of phenol undergoes substitution by dichlorocarbene mainly at the ortho position.
Step 3: Hydrolysis and acidification. Subsequent hydrolysis converts the intermediate into an aldehyde group. The final product is \[ o-\mathrm{HO-C_6H_4-CHO} \] which is salicylaldehyde.
Step 4: Identify the product. Hence the major product is \[ \boxed{\text{Salicylaldehyde}} \] and therefore, \[ \boxed{\text{Option (2)}} \]
Step 1: Formation of dichlorocarbene. Chloroform reacts with aqueous alkali. \[ \mathrm{CHCl_3 + OH^-} \rightarrow :\mathrm{CCl_2} \] Dichlorocarbene is generated.
Step 2: Electrophilic substitution on phenol. The activated aromatic ring of phenol undergoes substitution by dichlorocarbene mainly at the ortho position.
Step 3: Hydrolysis and acidification. Subsequent hydrolysis converts the intermediate into an aldehyde group. The final product is \[ o-\mathrm{HO-C_6H_4-CHO} \] which is salicylaldehyde.
Step 4: Identify the product. Hence the major product is \[ \boxed{\text{Salicylaldehyde}} \] and therefore, \[ \boxed{\text{Option (2)}} \]
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