Chemistry Aldehydes & Ketones NUMS 2022
PMDC Verified Question 43 of 94
Cannizzaro's reaction is given by:
A
Formaldehyde
B
Acetone
C
Acetaldehyde
D
Butanone
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option A: Formaldehyde
Concept:

The Cannizzaro reaction is a disproportionation reaction specific to aldehydes that lack alpha-hydrogen atoms.

Solution:

  • An alpha-hydrogen is a hydrogen atom attached to the carbon adjacent to the carbonyl group.


  • Formaldehyde (\( HCHO \)) has no alpha-carbon whatsoever, and therefore possesses zero alpha-hydrogens.


  • When treated with a strong concentrated base, it undergoes the Cannizzaro reaction to form methanol and sodium formate.


Why other options are incorrect:

Acetone, Acetaldehyde, and Butanone all possess alpha-hydrogens. When exposed to a base, they prefer to undergo deprotonation to form an enolate, driving the Aldol Condensation instead.

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