aldol vs cannizzaro

Question

Benzaldehyde under concentrated NaOH undergoes Cannizzaro because:

RankGuru · Accepted Answer

1. **Aldol Requirement**: The Aldol condensation requires an aldehyde or ketone to have at least one **$\alpha$-hydrogen** to form a nucleophilic enolate ion.
2. **Benzaldehyde Structure**: In $C_6H_5CHO$, the carbon adjacent to the carbonyl group is part of the benzene ring and has no hydrogens attached to it.
3. **Pathway Choice**: Since it **lacks $\alpha$-hydrogens**, it cannot undergo the Aldol reaction.
4. **Cannizzaro Reaction**: In the presence of concentrated strong base ($NaOH$), such aldehydes undergo a **disproportionation** (self-redox) reaction.
5. **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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aldol vs cannizzaro

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