Illustrated Glossary of Organic Chemistry

Wolff-Kishner reduction: A process for reduction of an aldehyde or ketone carbonyl group (C=O) into a methylene group (CH₂). The aldehyde or ketone is condensed with hydrazine to form a hydrazone. This hydrazone is then reduced by reaction with strong base to form a carbanion intermediate, which is subsequently protonated.

The Wolff-Kishner reduction of acetophenone begins by condensation with hydrazine (H₂NNH₂) to form acetophenone hydrazone. This hydrazone is then treated with sodium ethoxide (NaOCH₂CH₃; a strong base) in ethanol (CH₃CH₂OH; a protic solvent), resulting in loss of nitrogen and formation of a carbanion intermediate. This carbanion intermediate is then protonated by ethanol to give ethylbenzene, the reduction product.