Chemistry Aldehydes & Ketones SZABMU 2022
PMDC Verified Question 32 of 94
When aldehyde reacts with 50% NaOH, this reaction is called as:
A
2,4-DNPH reaction
B
Aldol condensation reaction
C
Clemmensen reaction
D
Cannizzaro's reaction
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option D: Cannizzaro's reaction
Concept:

Aldehydes lacking an alpha-hydrogen undergo a unique disproportionation reaction when exposed to concentrated strong bases.

Solution:

  • A 50% aqueous solution of \( NaOH \) is a highly concentrated base.


  • When an aldehyde with no alpha-hydrogens (like formaldehyde or benzaldehyde) is treated with this, it undergoes a self-oxidation-reduction.


  • One molecule is reduced to an alcohol, while another is oxidized to a carboxylic acid salt. This specific process is known as Cannizzaro's reaction.


Why other options are incorrect:

Aldol condensation requires dilute base (like 10% NaOH) and aldehydes possessing an alpha-hydrogen. Clemmensen is a reduction using Zn(Hg)/HCl. 2,4-DNPH is a condensation test for carbonyls.

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