Organic Chemistry -Aldehyde and
Ketones
Test Study Guide: -Enolate Chemistry
-General Principles
Ch.7 Enolates
-Aldol Condensation
-And More
CONCEPT SUMMARY
General Principles of Carbonyl Chemistry:
1. a-Carbon Identification: The carbon adjacent to the carbonyl carbon is referred to as the a-carbon, while the
hydrogens attached to this a-carbon are known as a-hydrogens.
2. Acidity of a-Hydrogens: a-Hydrogens exhibit relatively acidic properties and can be effectively removed by
strong bases.
3. C-H Bond Weakening: The presence of the electron-withdrawing oxygen in the carbonyl group contributes to
the weakening of C-H bonds on a-carbons.
4. Enolate Stability via Resonance: Upon deprotonation, the resulting enolate can be stabilized through resonance
with the carbonyl group.
5. Reactivity of Ketones: Ketones show reduced reactivity towards nucleophiles due to steric hindrance and
destabilization of the a-carbanion.
6. Impact of Alkyl Groups: An additional alkyl group introduces crowding in the transition state, leading to
increased energy and decreased stability of the carbanion due to electron density donation.
Points of Enolate Chemistry
1. Keto and Enol Forms
Aldehydes and ketones predominantly exist in the keto form (C=O), but can also exist in the enol form,
characterized by a double bond and a hydroxyl group (ene + ol).
2. Tautomerism
Tautomers are isomers that can be interconverted through the migration of a hydrogen atom and a double bond.
The keto and enol forms are examples of such tautomers.
3. Formation of Enolates
The enol form can undergo deprotonation to yield an enolate, which serves as a strong nucleophile in chemical
reactions.
4. Michael Addition Reaction
In the Michael addition mechanism, an enolate attacks an α,β-unsaturated carbonyl compound, resulting in the
formation of a new carbon-carbon bond.
5. Kinetic vs. Thermodynamic Enolates
Kinetic enolates are favored under conditions of fast, irreversible reactions at lower temperatures using strong,
sterically hindered bases.
Ketones
Test Study Guide: -Enolate Chemistry
-General Principles
Ch.7 Enolates
-Aldol Condensation
-And More
CONCEPT SUMMARY
General Principles of Carbonyl Chemistry:
1. a-Carbon Identification: The carbon adjacent to the carbonyl carbon is referred to as the a-carbon, while the
hydrogens attached to this a-carbon are known as a-hydrogens.
2. Acidity of a-Hydrogens: a-Hydrogens exhibit relatively acidic properties and can be effectively removed by
strong bases.
3. C-H Bond Weakening: The presence of the electron-withdrawing oxygen in the carbonyl group contributes to
the weakening of C-H bonds on a-carbons.
4. Enolate Stability via Resonance: Upon deprotonation, the resulting enolate can be stabilized through resonance
with the carbonyl group.
5. Reactivity of Ketones: Ketones show reduced reactivity towards nucleophiles due to steric hindrance and
destabilization of the a-carbanion.
6. Impact of Alkyl Groups: An additional alkyl group introduces crowding in the transition state, leading to
increased energy and decreased stability of the carbanion due to electron density donation.
Points of Enolate Chemistry
1. Keto and Enol Forms
Aldehydes and ketones predominantly exist in the keto form (C=O), but can also exist in the enol form,
characterized by a double bond and a hydroxyl group (ene + ol).
2. Tautomerism
Tautomers are isomers that can be interconverted through the migration of a hydrogen atom and a double bond.
The keto and enol forms are examples of such tautomers.
3. Formation of Enolates
The enol form can undergo deprotonation to yield an enolate, which serves as a strong nucleophile in chemical
reactions.
4. Michael Addition Reaction
In the Michael addition mechanism, an enolate attacks an α,β-unsaturated carbonyl compound, resulting in the
formation of a new carbon-carbon bond.
5. Kinetic vs. Thermodynamic Enolates
Kinetic enolates are favored under conditions of fast, irreversible reactions at lower temperatures using strong,
sterically hindered bases.
