Chemistry of Carbonyl Compounds - Keto-enol Tautomerism and Enolate Formation

These flashcards cover key concepts from the second lecture on the chemistry of carbonyl compounds, focusing on keto-enol tautomerism and enolate formation.

What is keto-enol tautomerism?

It is the equilibrium between keto and enol forms of a carbonyl compound.

What stabilizes the enolate anion formed from a carbonyl compound?

The enolate anion is stabilized by resonance due to delocalization over the adjacent carbonyl.

Which base is commonly used for enolate formation?

Sodium methoxide (MeO-Na) is a common base used to form enolates.

In the presence of a strong acid, what happens to a ketone in terms of tautomerization?

The ketone undergoes tautomerization to form the enol.

What factors can increase the stability of the enol form?

Factors include solvent polarity, conjugation, and intramolecular hydrogen bonding.

How do 1,3-dicarbonyl compounds affect enolate stability?

The enolate formed from 1,3-dicarbonyls is more stable due to resonance structures.

What is the typical concentration of enols in the absence of a strong acid catalyst?

Enols are present at minuscule concentrations (around 1 x 10-8) without a strong acid catalyst.

What is the thermodynamic stability of keto vs enol forms?

Keto forms are thermodynamically more stable than enol forms.

What is the effect of bromine on enol nucleophilicity during acid-catalyzed bromination?

The presence of bromine as an electron-withdrawing group deactivates the enol, leading to monobromination.

Where does the equilibrium lie when forming an enolate from a ketone?

The equilibrium lies on the side of the starting materials, meaning the ketone is the predominant species.