Diketene is produced by dimerization of ketene (CH₂=C=O), which is generated by thermal cracking of acetic acid or acetone. It is a versatile C₄ synthon used to introduce the acetoacetyl group (CH₃COCH₂CO-) into target molecules. Industrial applications include synthesis of methyl and ethyl acetoacetate (solvent/flavor), aceto-acetanilide (pigment intermediate), 2,2,6-trimethyl-4H-1,3-dioxin-4-one (Michler's base chemistry), acetoacetyl esters of long-chain alcohols, and various food-color and pharmaceutical intermediates.
Diketene itself is not permitted in food — it is strictly an intermediate whose reaction products are purified and isolated before entering the food supply chain. Technical grade typically ≥ 98% purity. Extremely reactive with water, amines, and alcohols; requires anhydrous storage under inert atmosphere at cool temperatures.