Question
Explain the mechanism of Cannizaro reaction.
✓
Answer
1. In the presence of concentrated aqueous or alcoholic alkali, aldehydes which do not have $\alpha$ - hydrogen atom undergo self oxidation and reduction to give a mixture of alcohol and a salt of carboxylic acid. This reaction is called Cannizaro reaction.
2. Benzaldehyde on treatment with concentrated $NaOH (50 \%)$ gives benzyl alcohol and sodium benzoate.
Mechanism
Cannizaro reaction involves three steps.
3. Step 1:
Attack of $OH^–$ on the carbonyl carbons.
4. Step 2:
Hydride ion transfer
5. Step 3:
Acid – base reaction
2. Benzaldehyde on treatment with concentrated $NaOH (50 \%)$ gives benzyl alcohol and sodium benzoate.
Mechanism
Cannizaro reaction involves three steps.
3. Step 1:
Attack of $OH^–$ on the carbonyl carbons.
4. Step 2:
Hydride ion transfer
5. Step 3:
Acid – base reaction
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