Question

Phenol is subjected to the following sequence of reactions: \[ \text{Phenol} \xrightarrow{\text{Kolbe-Schmitt}} A \xrightarrow{\text{SOCl}_2} B \xrightarrow{\text{Clemmensen Reduction}} C \xrightarrow{\text{Reimer-Tiemann}} D \] The functional group present in the final product \(D\) is:

• A. Only \(-CHO\)
• B. Only \(-COOH\)
• C. Both \(-OH\) and \(-CHO\)
• D. Both \(-OH\) and \(-COOH\)

Hint:

Reimer-Tiemann reaction introduces a formyl group ortho to the phenolic hydroxyl group.

Answer 1

The Correct Option is C

Concept: This problem integrates four important named reactions from NCERT organic chemistry.

Step 1: Kolbe-Schmitt reaction. Phenol forms sodium phenoxide which reacts with \(CO_2\). Product: \[ o\text{-hydroxybenzoic acid} \] (salicylic acid)

Step 2: Reaction with \(SOCl_2\). The carboxylic acid is converted into acid chloride. \[ -COOH \rightarrow -COCl \]

Step 3: Clemmensen reduction. The acyl functionality is reduced to a methyl group. Thus: \[ o\text{-cresol} \] is formed.

Step 4: Reimer-Tiemann reaction. Phenolic compounds on treatment with \[ CHCl_3/KOH \] undergo formylation. The major product contains: \[ -OH \] and \[ -CHO \] groups. Hence the final compound possesses both functionalities. \[ \boxed{\text{Both } -OH \text{ and } -CHO} \]