Question:
Which of the following oxidising agent is used to convert ethanol to ethanal?
Which of the following oxidising agent is used to convert ethanol to ethanal?
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Standard reagents to convert alcohol \(\to\) aldehyde: PCC (Pyridinium Chlorochromate) or \(CrO_3\) in anhydrous medium. Using acidified \(KMnO_4\) will "overshoot" the reaction to the carboxylic acid.
Updated On: Jun 24, 2026
- Acidified \(KMnO_4\)
- Alkaline \(KMnO_4\)
- Acidified \(K_2Cr_2O_7\)
- \(H_2O_2\) in anhydrous medium
- \(CrO_3\) in anhydrous medium
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The Correct Option is
Solution and Explanation
Step 1: Understanding the Concept:
Ethanol is a primary alcohol, and ethanal is an aldehyde. Strong oxidizing agents (like acidified \(KMnO_4\) or \(K_2Cr_2O_7\)) usually oxidize primary alcohols directly to carboxylic acids (ethanoic acid).
Step 2: Detailed Explanation:
1. To stop the oxidation at the aldehyde stage, a controlled or mild oxidizing agent is required.
2. Chromium trioxide (\(CrO_3\)) in an anhydrous (water-free) medium like glacial acetic acid or as a complex (like PCC or Collins reagent) is used for this selective oxidation.
3. In the presence of water, the aldehyde hydrate is formed, which is further oxidized to the acid. Anhydrous conditions prevent this.
Step 3: Final Answer:
\(CrO_3\) in anhydrous medium is used to convert ethanol to ethanal.
Ethanol is a primary alcohol, and ethanal is an aldehyde. Strong oxidizing agents (like acidified \(KMnO_4\) or \(K_2Cr_2O_7\)) usually oxidize primary alcohols directly to carboxylic acids (ethanoic acid).
Step 2: Detailed Explanation:
1. To stop the oxidation at the aldehyde stage, a controlled or mild oxidizing agent is required.
2. Chromium trioxide (\(CrO_3\)) in an anhydrous (water-free) medium like glacial acetic acid or as a complex (like PCC or Collins reagent) is used for this selective oxidation.
3. In the presence of water, the aldehyde hydrate is formed, which is further oxidized to the acid. Anhydrous conditions prevent this.
Step 3: Final Answer:
\(CrO_3\) in anhydrous medium is used to convert ethanol to ethanal.
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