Reference Reaction Summary Tables Nucleophilic Addition to Aldehydes and Ketones
Nucleophilic Addition to Aldehydes and Ketones
Estimated reading time: 1 min
In this section
- Overview
- Substitution and Elimination (SN1, SN2, E1, E2)
- Addition to Alkenes and Alkynes
- Nucleophilic Addition to Aldehydes and Ketones
- Nucleophilic Acyl Substitution (Carboxylic Acid Derivatives)
- Enols, Enolates, and Carbon–Carbon Bond Formation
- Electrophilic Aromatic Substitution
- Addition vs. Substitution at Carbonyls — A Direct Comparison
- Cross-References
| Reaction | Typical Reagents/Conditions | Product | Common Pitfall |
|---|---|---|---|
| Hydration | H₂O | Geminal diol (hydrate) | Assuming this equilibrium always favors the hydrate — for most ketones, the carbonyl form is favored |
| Reduction | NaBH₄ or LiAlH₄, then aqueous workup | Alcohol | Using the same reagent for reducing a carboxylic acid derivative — NaBH₄ is generally too weak for esters/amides, while LiAlH₄ is strong enough to reduce those as well |
| Organometallic addition | Grignard reagent (RMgX) or organolithium (RLi), then aqueous workup | New C–C bond; alcohol | Forgetting that these are strong bases as well as strong nucleophiles — they are incompatible with acidic protons (O–H, N–H) elsewhere in the molecule |
| Hemiacetal/acetal formation | Alcohol (ROH), acid catalyst | Hemiacetal (1 equiv. ROH) or acetal (2 equiv. ROH, water removed) | Forgetting that this is reversible — acetals hydrolyze back to the carbonyl under aqueous acid, which is exactly why they are useful as protecting groups |
Every reaction in this table follows the same general pattern introduced in Chapter 12: a nucleophile attacks the electrophilic carbonyl carbon, electron density shifts onto oxygen, and (where applicable) a proton transfer restores neutrality.