Knoevenagel condensation is a chemical reaction named after the German chemist Emil Knoevenagel, who first reported it in 1898. This reaction involves the condensation of an aldehyde or ketone with an active methylene compound, usually in the presence of a base catalyst, to form an α,β-unsaturated carbonyl compound. The base catalyst is often a weak base like ammonia, primary or secondary amines, or even potassium carbonate in some cases.