What is an enolate?

An enolate is a species that forms when a carbonyl compound, typically a ketone or aldehyde, undergoes deprotonation at an alpha-carbon, resulting in a resonance-stabilized anion. This anion is characterized by having a carbon atom adjacent to a carbonyl group that carries a negative charge, making it a highly reactive intermediate.

The resonance structures of an enolate allow it to be represented as having a double bond between the alpha carbon and the carbonyl carbon while also having a negative charge localized on the alpha carbon or the carbonyl oxygen. This ability to delocalize charge through resonance provides the enolate with significant nucleophilic character, enabling it to effectively attack electrophiles in various reactions, such as the aldol condensation or the Michael addition.

Thus, the identification of an enolate as a good nucleophile highlights its role in organic reactions where it can participate in nucleophilic attacks due to its negatively charged nature, making it a crucial player in many synthetic pathways in organic chemistry.