Glioxal : O=HC-CH=O (poate fi numai componenta carbonilica) Butanona: CH3-CO-CH2-CH3 (are 2 pozitii drept componenta metilenica) O=CH-CH=O + CH3-CO-CH2-CH3  --> O=CH-CH=CH-CO-CH2-CH3  O=CH-CH=O + Ch3-CO-CH2-CH3  --> O=CH-CH=C(CH3)-CO-CH3