Question:
Identify the reagent used in Etard reaction
Identify the reagent used in Etard reaction
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Etard reaction oxidises toluene to benzaldehyde using chromyl chloride followed by hydrolysis.
Updated On: Oct 1, 2026
- Acetic anhydride
- Anhydrous aluminum chloride
- DIBAL-H
- Chromyl chloride
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Verified By Collegedunia
The Correct Option is D
Solution and Explanation
Step 1: Understanding the Concept:
The Etard reaction is a named method that converts an aromatic methyl group into an aldehyde group without going on to the acid.
Step 2: Key Formula or Approach:
Toluene reacts with chromyl chloride (\(\text{CrO}_2\text{Cl}_2\)) in \(\text{CS}_2\) to give a chromium complex. Hydrolysis with water gives benzaldehyde.
Step 3: Detailed Explanation:
\[ \text{C}_6\text{H}_5\text{CH}_3 \xrightarrow{\text{CrO}_2\text{Cl}_2,\ \text{CS}_2} \text{complex} \xrightarrow{\text{H}_3\text{O}^+} \text{C}_6\text{H}_5\text{CHO} \]
Step 4: Why the other options are wrong.
Chromic oxide in acetic anhydride is a different oxidation of toluene that gives benzylidene diacetate. Anhydrous \(\text{AlCl}_3\) is the catalyst in Friedel-Crafts and Gattermann-Koch reactions. DIBAL-H reduces esters and nitriles to aldehydes.
Final Answer:
The Etard reaction uses chromyl chloride, option (D). \[ \boxed{\text{CrO}_2\text{Cl}_2} \]
The Etard reaction is a named method that converts an aromatic methyl group into an aldehyde group without going on to the acid.
Step 2: Key Formula or Approach:
Toluene reacts with chromyl chloride (\(\text{CrO}_2\text{Cl}_2\)) in \(\text{CS}_2\) to give a chromium complex. Hydrolysis with water gives benzaldehyde.
Step 3: Detailed Explanation:
\[ \text{C}_6\text{H}_5\text{CH}_3 \xrightarrow{\text{CrO}_2\text{Cl}_2,\ \text{CS}_2} \text{complex} \xrightarrow{\text{H}_3\text{O}^+} \text{C}_6\text{H}_5\text{CHO} \]
Step 4: Why the other options are wrong.
Chromic oxide in acetic anhydride is a different oxidation of toluene that gives benzylidene diacetate. Anhydrous \(\text{AlCl}_3\) is the catalyst in Friedel-Crafts and Gattermann-Koch reactions. DIBAL-H reduces esters and nitriles to aldehydes.
Final Answer:
The Etard reaction uses chromyl chloride, option (D). \[ \boxed{\text{CrO}_2\text{Cl}_2} \]
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