Acetylacetone ( 2,4 -pentanedione) reacts with sodium...

Name: Problem 31, Chapter 4: Organic Chemistry
Uploaded: 2021-06-22T16:08:09-08:00
Duration: 4 min 50 s
Channel: Nicholas Sacco
Description: Acetylacetone ( 2,4 -pentanedione) reacts with sodium hydroxide to give water and the sodium salt of a carbanion. Write a complete structural formula for the carbanion, and use resonance forms to show the stabilization of the carbanion.

Acetylacetone ( 2,4 -pentanedione) reacts with sodium hydroxide to give water and the sodium salt of a carbanion. Write a complete structural formula for the carbanion, and use resonance forms to show the stabilization of the carbanion.

Key Concepts

Acidity of Alpha Protons

In carbonyl compounds, the hydrogen atoms adjacent to the carbonyl group (alpha protons) are more acidic than in typical alkanes. This enhanced acidity arises because the negative charge formed upon deprotonation can be stabilized by resonance with the adjacent carbonyl group, making it easier for a base to remove these protons.

Enolate Ion Formation

When a base deprotonates an alpha hydrogen of a carbonyl compound, an enolate ion is formed. The enolate ion is characterized by a negative charge on the alpha carbon, which is delocalized over the oxygen atom of the carbonyl group, thereby stabilizing the ion.

Resonance Stabilization

Resonance stabilization refers to the delocalization of electrons across adjacent atoms in a molecule. In the case of the enolate ion, the negative charge that initially resides on the alpha carbon can be shared between multiple atoms (the carbonyl oxygen and the alpha carbon), creating several contributing resonance structures that collectively lower the overall energy of the ion.

Resonance Structures Representation

Resonance structures are different Lewis structures that depict the same molecule but with the placement of electrons shifted. For the enolate ion, drawing multiple resonance forms illustrates how the negative charge is spread between the alpha carbon and the oxygen, highlighting the stabilization provided by this delocalization.

Transcript

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