Question

Propose a mechanism for the conjugate addition of a nucleophile (Nuc:-) to acrylonitrile (H2C=CHCN) and to nitroethylene. Use resonance forms to show how the cyano and nitro groups activate the double bond toward conjugate addition.

Short answer

Conjugate addition of a nucleophile to the double bond of acrylonitrile α,β-unsaturated compound is called a Michael addition.

The electrophile acrylonitrile accepts a pair of electrons, so it is called the Michael acceptor. The attacking nucleophile donates a pair of electrons, so it is called the Michael donor.

Conjugate addition of nucleophile to acrylonitrile is shown as follows:

Conjugate addition of nucleophile to acrylonitrile

Step-by-step solution

Conjugate addition of nucleophile to acrylonitrile

Conjugate addition of a nucleophile to the double bond of acrylonitrile α,β-unsaturated compound is called a Michael addition.

The electrophile acrylonitrile accepts a pair of electrons, so it is called the Michael acceptor. The attacking nucleophile donates a pair of electrons, so it is called the Michael donor.

Conjugate addition of nucleophile to acrylonitrile is shown as follows:

Conjugate addition of nucleophile to acrylonitrile