Ethyl acetoacetate (EAA) is a beta-ketone ester that contains carbon (C), hydrogen (H) and oxygen (O) and has the empirical formula C6H10O3. It can be prepared by Claisen condensation of ethyl acetate with sodium acetate or some modification of this procedure. Ethyl acetoacetate finds several important applications, both commercial and scientific. The food industry uses it in a variety of ways, and it is used in medications as well as as an intermediate in lacquer, paints and other surface preparations. At the research level, the ester is an important reagent in organic synthesis and ligand chemistry.
EAA gives off a pleasant, fruity aroma. This makes it a popular synthetic for use in flavoring and fragrance applications, whether as is or modified chemically, as in the case of fructone. In addition, food manufacturers use the substance in resinous and polymeric coatings. Such coatings can be used on equipment or surfaces food contacts, or it can be used to a limited degree in the foods themselves.
Ethyl acetoacetate can be used in non-food-related surface coatings or textiles as an accelerant in the cure process. Termed a promoter or co-promoter, approximately 1-3 percent EAA is added by weight to the unsaturated polyester resin. In other products, EAA can be added as a solvent, a stabilizer or a catalyst. When more extensively modified, acetoacetic acid derivatives find application in dyes, pigments and agrochemicals. Acetoacetoxyethyl methacrylate is used in co-polymerization to reduce viscosity in adhesives.
Laboratory research has continued to reveal new substances and applications for ethyl acetoacetate. The molecule actually exists in two forms, one an “enol” form, the other a “keto” form — the form usually drawn to identify the molecule. These two forms can interchange. This property is called keto-enol tautomerism. In its enol form, EAA can act like a bi-dentate ligand, meaning that each molecule can act much like a pair of crab claws ready to attack an atom, generally of a transition metal.
The claws form coordination bonds to these atoms within their grasp. One example of a coordinately bonded transition metal complex is the reaction between three EAA molecules and a single atom of trivalent, or +3-iron. Another example is the reaction between a molecule of ethyl acetoacetate and n-butyl lithium in pentane. In this reaction, a six-member ring is generated, with the lithium atom and two oxygen atoms being counted in among the ring members. Other reaction types include those of the organic chemist, using ethyl acetoacetate much as any other starting material is used, when it is the tool of choice.
