Illustrated Glossary of Organic Chemistry

Nucleophilic addition: An addition reaction or mechanism step in which a nucleophile adds to a pi bond.

The carbonyl fate "capture a nucleophile" is a nucleophilic addition mechanism step. In this example, hydroxide ion adds to the δ+ carbon end of a carbonyl group, forming an oxyanionic tetrahedral intermediate. The net result is addition of water (HO-H) across the carbonyl group pi bond.

In a Michael addition reaction, a carbon nucleophile attacks the carbon-carbon pi bond of an α,β-unsaturated carbonyl compound. In this example, lithium diphenylcuprate (Ph2CuLi; an organocopper nucleophile) adds to the carbon-carbon pi bond of methyl methacrylate, an α,β-unsaturated ester.