Aldol Vs Cannizzaro
Mediumchemistry
Benzaldehyde under concentrated NaOH undergoes Cannizzaro because:
Select the correct option:
Solution
Incorrect! Answer:
Lacks α-hydrogen preventing aldol condensation
- Aldol Requirement: The Aldol condensation requires an aldehyde or ketone to have at least one α-hydrogen to form a nucleophilic enolate ion.
- Benzaldehyde Structure: In C6H5CHO, the carbon adjacent to the carbonyl group is part of the benzene ring and has no hydrogens attached to it.
- Pathway Choice: Since it lacks α-hydrogens, it cannot undergo the Aldol reaction.
- Cannizzaro Reaction: In the presence of concentrated strong base (NaOH), such aldehydes undergo a disproportionation (self-redox) reaction.
- Products: One molecule is reduced to an alcohol (Benzyl alcohol) and another is oxidized to a carboxylic acid salt (Sodium benzoate).
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About This Question
- Subject
- chemistry
- Chapter
- oxygen organics
- Topic
- aldol vs cannizzaro
- Difficulty
- Medium
- Year
- 2025
Solution
Correct Answer:
Lacks α-hydrogen preventing aldol condensation
- Aldol Requirement: The Aldol condensation requires an aldehyde or ketone to have at least one α-hydrogen to form a nucleophilic enolate ion.
- Benzaldehyde Structure: In C6H5CHO, the carbon adjacent to the carbonyl group is part of the benzene ring and has no hydrogens attached to it.
- Pathway Choice: Since it lacks α-hydrogens, it cannot undergo the Aldol reaction.
- Cannizzaro Reaction: In the presence of concentrated strong base (NaOH), such aldehydes undergo a disproportionation (self-redox) reaction.
- Products: One molecule is reduced to an alcohol (Benzyl alcohol) and another is oxidized to a carboxylic acid salt (Sodium benzoate).
This medium difficulty chemistry question is from the chapter oxygen organics, covering the topic of aldol vs cannizzaro. It appeared in the 2025 exam.
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