Alpha-carbon chemistry is where acidity, resonance, and carbonyl reactivity converge, enabling tautomerism, halogenation, alkylation, and the bond-forming reactions that dominate later synthesis.
Describe keto–enol tautomerism and explain why the keto form is usually favored.
Draw enolate resonance contributors and identify carbon versus oxygen nucleophilicity conceptually.
Choose conditions for kinetic versus thermodynamic enolate formation.
Predict alpha halogenation and alpha alkylation outcomes for carbonyl compounds.
Checkpoint Questions
Q: Why are alpha hydrogens next to a carbonyl much more acidic than alkane hydrogens?
A: Because deprotonation forms a resonance-stabilized enolate rather than a localized carbanion.
Q: When would you choose LDA at low temperature?
A: When you want rapid, irreversible deprotonation and often the less substituted kinetic enolate.