Knoevenagel Condensation
Condensation of aldehydes or ketones with compounds having active methylene group in the presence of basic catalyst such as ammonia and its derivatives to form α, β-unsaturated carbonyl compounds. This reaction is known as Knoevenagel Condensation.
In other words, Knoevenagel condensation is a nucleophilic addition of an activated methylene compound to an aldehyde or ketone using an amine base (e.g., pyridine or piperidine) as a catalyst followed by a dehydration in which a molecule of water is eliminated (condensation) and an α,β-unsaturated carbonyl compound obtained.
Both aliphatic and aromatic aldehydes give this reaction. For steric and electronic effect, ketones are less reactive than aldehydes. Ketones can reacts only when active methylene group is very powerfull(e.g. cyanoacetic acid, ethylacetoacetate).
In other words, Knoevenagel condensation is a nucleophilic addition of an activated methylene compound to an aldehyde or ketone using an amine base (e.g., pyridine or piperidine) as a catalyst followed by a dehydration in which a molecule of water is eliminated (condensation) and an α,β-unsaturated carbonyl compound obtained.
Both aliphatic and aromatic aldehydes give this reaction. For steric and electronic effect, ketones are less reactive than aldehydes. Ketones can reacts only when active methylene group is very powerfull(e.g. cyanoacetic acid, ethylacetoacetate).
