Overall reaction
CH₂(COOEt)₂ + CH₂=CHCOCH₃ → (NaOEt) (EtOOC)₂CH–CH₂CH₂COCH₃
Conjugate (1,4-) addition of an enolate to an enone.
Name reaction · mechanism
Michael Addition
The Michael addition is the conjugate (1,4-) addition of a stabilised carbanion — a malonate, β-keto ester or nitroalkane anion — to the β-carbon of an α,β-unsaturated carbonyl compound. The enolate formed is then protonated to give a 1,5-dicarbonyl compound.
Mechanism step by step
- Conjugate addition. The enolate attacks the β-carbon
- Protonation. Water protonates the new enolate
Each step is checked electron by electron: the curly arrows give exactly the structures drawn.
Key points
- Soft, stabilised nucleophiles add 1,4; hard ones (RLi) add 1,2.
- Gives 1,5-dicarbonyl compounds.
- With an aldol ring closure afterwards: the Robinson annulation.
- The base is regenerated: it is catalytic.
For JEE and NEET
- Soft, stabilised nucleophiles add 1,4; hard ones (RLi, RMgX) tend to add 1,2.
- Organocuprates (R₂CuLi) also add 1,4.
- Michael + intramolecular aldol = Robinson annulation.
- Product: a 1,5-dicarbonyl compound.
FAQ
Why does the nucleophile attack the β-carbon?
Conjugation with C=O makes the β-carbon electrophilic, and soft stabilised carbanions prefer this orbital-controlled site.
Michael donor vs acceptor?
The donor is the stabilised carbanion (malonate, acetoacetate); the acceptor is the α,β-unsaturated carbonyl or nitrile.
How is it related to the Robinson annulation?
The Robinson annulation is a Michael addition followed by an intramolecular aldol condensation that closes a six-membered ring.
Draw it in MolDraw
The button above opens the complete figure — overall reaction, numbered mechanism and key points — as ordinary editable structures. Change substituents, recolour atoms, or export a PNG, SVG or chemfig code for notes and slides. The same figure is in the Templates panel under Name reactions.