Question

Which will undergo deprotonation most readily in basic medium?

• A. Both a and c
• B. a only
• C. b only
• D. c only

Hint:

Resonance stabilization of the conjugate base increases the acidity of the compound, favoring deprotonation.

Answer 1

The Correct Option is B

To determine which compound will undergo deprotonation most readily in a basic medium, we need to analyze the structures of the given compounds. The compounds provided were: 

1. Compound Analysis
   • Compound a is a simple 1,3-diketone, which is commonly known for its ability to stabilize negative charges through resonance after deprotonation.
   • Compound b contains ester groups along with the diketone. The presence of the ester groups can reduce the acidity of the hydrogen atoms between the carbonyls due to decreased resonance stabilization compared to a simple diketone.
   • Compound c is a β-diketone similar to compound a, but with an ester group that destabilizes the enolate ion, similar to compound b.
2. Resonance Stabilization:
   • The acidity of a hydrogen atom in a compound is influenced by the ability of the compound to stabilize the negative charge resulting from deprotonation. In compound a, the resulting enolate ion can be significantly stabilized by resonance with the two carbonyl groups.
   • The resonance effect is less significant in compounds b and c due to the presence of ester groups that reduce the overall resonance stabilization available to the enolate ion.
3. Conclusion:
   • Compound a will undergo deprotonation most readily due to the high resonance stabilization offered by its 1,3-diketone structure. This makes option a only the correct choice.