Question:
Identify product C in following conversion:
m-Hydroxy Benzaldehyde $\xrightarrow{\text{[Protection of -OH group]} \, \text{C}_6\text{H}_5\text{CH}_2\text{Cl}} \text{A} \xrightarrow{\text{[O]}} \text{B} \xrightarrow{\text{[deprotection of -OH group]}} \text{C}$
Identify product C in following conversion:
m-Hydroxy Benzaldehyde $\xrightarrow{\text{[Protection of -OH group]} \, \text{C}_6\text{H}_5\text{CH}_2\text{Cl}} \text{A} \xrightarrow{\text{[O]}} \text{B} \xrightarrow{\text{[deprotection of -OH group]}} \text{C}$
m-Hydroxy Benzaldehyde $\xrightarrow{\text{[Protection of -OH group]} \, \text{C}_6\text{H}_5\text{CH}_2\text{Cl}} \text{A} \xrightarrow{\text{[O]}} \text{B} \xrightarrow{\text{[deprotection of -OH group]}} \text{C}$
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Look closely at the chemical logic: protection and deprotection mean you start and end with the exact same functional group (-OH) at that specific position. The only permanent chemical change in the whole process is the oxidation of the aldehyde to a carboxylic acid.
Updated On: Jun 12, 2026
- Benzoic acid
- m-Hydroxybenzoic acid
- Phenol
- Phenyl benzoate
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The Correct Option is B
Solution and Explanation
Step 1: Understanding the Question:
We are dealing with a multi-step organic synthesis sequence. An aldehyde group (-CHO) needs to be oxidized to a carboxylic acid (-COOH) on a benzene ring that also contains a sensitive phenolic hydroxyl (-OH) group.
Step 2: Key Formula or Approach:
Phenolic -OH groups are highly vulnerable to direct oxidation reactions. Therefore, protection-deprotection strategy is utilized. Benzyl chloride ($\text{C}_6\text{H}_5\text{CH}_2\text{Cl}$) protects the -OH group as a benzyl ether. Then, the aldehyde is oxidized, and finally, deprotection restores the original -OH group.
Step 3: Detailed Explanation:
1.
Protection Step: m-Hydroxybenzaldehyde reacts with $\text{C}_6\text{H}_5\text{CH}_2\text{Cl}$ to form m-benzyloxybenzaldehyde (Product A). The phenolic oxygen is now structurally shielded.
2.
Oxidation Step: Product A undergoes selective oxidation using an oxidizing agent [O]. The unprotected formyl functional group (-CHO) is oxidized smoothly to a carboxylic acid group (-COOH), yielding m-benzyloxybenzoic acid (Product B).
3.
Deprotection Step: Product B undergoes clearing/deprotection (typically via catalytic hydrogenation or acid hydrolysis) to remove the benzyl group. This returns the ether back into the original phenolic -OH group without altering the newly formed acid group. The final structure is m-hydroxybenzoic acid.
Step 4: Final Answer:
The product C is m-hydroxybenzoic acid, which is perfectly represented by option (B).
We are dealing with a multi-step organic synthesis sequence. An aldehyde group (-CHO) needs to be oxidized to a carboxylic acid (-COOH) on a benzene ring that also contains a sensitive phenolic hydroxyl (-OH) group.
Step 2: Key Formula or Approach:
Phenolic -OH groups are highly vulnerable to direct oxidation reactions. Therefore, protection-deprotection strategy is utilized. Benzyl chloride ($\text{C}_6\text{H}_5\text{CH}_2\text{Cl}$) protects the -OH group as a benzyl ether. Then, the aldehyde is oxidized, and finally, deprotection restores the original -OH group.
Step 3: Detailed Explanation:
1.
Protection Step: m-Hydroxybenzaldehyde reacts with $\text{C}_6\text{H}_5\text{CH}_2\text{Cl}$ to form m-benzyloxybenzaldehyde (Product A). The phenolic oxygen is now structurally shielded.
2.
Oxidation Step: Product A undergoes selective oxidation using an oxidizing agent [O]. The unprotected formyl functional group (-CHO) is oxidized smoothly to a carboxylic acid group (-COOH), yielding m-benzyloxybenzoic acid (Product B).
3.
Deprotection Step: Product B undergoes clearing/deprotection (typically via catalytic hydrogenation or acid hydrolysis) to remove the benzyl group. This returns the ether back into the original phenolic -OH group without altering the newly formed acid group. The final structure is m-hydroxybenzoic acid.
Step 4: Final Answer:
The product C is m-hydroxybenzoic acid, which is perfectly represented by option (B).
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