Chemistry Aldehydes & Ketones BUMHS 2023
PMDC Verified Question 24 of 94
Which of the following characteristic of carbonyl oxygen increases by base-catalyzed reaction?
A
Amphoteric
B
Nucleophilic
C
Electrophonic
D
Electrophilic
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option B: Nucleophilic
Concept:

In base-catalyzed reactions involving carbonyls (like Aldol condensation), the base abstracts a proton to form a highly reactive intermediate.

Solution:

  • When a base removes an alpha-hydrogen from a carbonyl compound, it generates a carbanion (enolate).


  • This enolate has a major resonance structure where the negative charge is delocalized onto the highly electronegative oxygen atom (\( -C=C-O^- \)).


  • Because the oxygen atom now bears a full formal negative charge (compared to its neutral, partially negative state), its ability to donate electrons has massively increased.


  • Therefore, the nucleophilic character of the oxygen is significantly increased.


Why other options are incorrect:

Electrophilic means "electron-loving" (seeking negative charge), which oxygen is not doing here as it is already electron-rich. Amphoteric refers to acting as both acid and base, which doesn't specifically increase here.

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