The
organic compound
Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon–carbon bond; others consider an organic compound to be any chemical compound that contains carbon. For example, carbon-co ...
ethyl acetoacetate (EAA) is the
ethyl ester
In chemistry, an ester is a compound derived from an acid (either organic or inorganic) in which the hydrogen atom (H) of at least one acidic hydroxyl group () of that acid is replaced by an organyl group (R). These compounds contain a distin ...
of
acetoacetic acid
Acetoacetic acid ( IUPAC name: 3-oxobutanoic acid, also known as acetonecarboxylic acid or diacetic acid) is the organic compound with the formula CHCOCHCOOH. It is the simplest beta- keto acid, and like other members of this class, it is unstabl ...
. It is a colorless liquid. It is widely used as a
chemical intermediate in the production of a wide variety of compounds.
Preparation
At large scale, ethyl acetoacetate is industrially produced by treatment of
diketene with
ethanol
Ethanol (also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound with the chemical formula . It is an Alcohol (chemistry), alcohol, with its formula also written as , or EtOH, where Et is the ps ...
.
The small scale preparation of ethyl acetoacetate is a classic laboratory procedure. It involves
Claisen condensation
The Claisen condensation is a carbon–carbon bond forming reaction that occurs between two esters or one ester and another carbonyl compound in the presence of a strong base. The reaction produces a β-keto ester or a β- diketone. It is named ...
of
ethyl acetate
Ethyl acetate commonly abbreviated EtOAc, ETAC or EA) is the organic compound with the formula , simplified to . This flammable, colorless liquid has a characteristic sweet smell (similar to pear drops) and is used in glues, nail polish removers, ...
. Two moles of ethyl acetate condense to form one mole each of ethyl acetoacetate and ethanol.
:
Reactions
Ethyl acetoacetate is subject to
keto-enol tautomerism. In the neat liquid at 33 °C, the enol consists of 8% of the total.
The enol is moderately acidic. Thus ethyl acetoacetate behaves similarly to
acetylacetone
Acetylacetone is an organic compound with the chemical formula . It is classified as a 1,3-diketone. It exists in equilibrium with a tautomer . The mixture is a colorless liquid. These tautomers interconvert so rapidly under most conditions that ...
:
[
:
The resulting carbanion undergoes ]nucleophilic substitution
In chemistry, a nucleophilic substitution (SN) is a class of chemical reactions in which an electron-rich chemical species (known as a nucleophile) replaces a functional group within another electron-deficient molecule (known as the electrophile) ...
. Ethyl acetoacetate is often used in the acetoacetic ester synthesis, comparable to diethyl malonate in the malonic ester synthesis or the Knoevenagel condensation
In organic chemistry, the Knoevenagel condensation () reaction is a type of chemical reaction named after German chemist Emil Knoevenagel. It is a modification of the aldol condensation.
A Knoevenagel condensation is a nucleophilic addition o ...
. After its alkylation and saponification, thermal decarboxylation is also possible.
The dianion of ethyl acetoacetate is also a useful building block, except that the electrophile adds to the terminal carbon. The strategy can be depicted in the following simplified form:butyl
In organic chemistry, butyl is a four-carbon alkyl radical or substituent group with general chemical formula , derived from either of the two isomers (''n''-butane and isobutane) of butane.
The isomer ''n''-butane can connect in two ways, giv ...
)
Reduction of ethyl acetoacetate gives ethyl 3-hydroxybutyrate.
Ethyl acetoacetate transesterifies to give benzyl acetoacetate via a mechanism involving acetylketene. Ethyl (and other) acetoacetates nitrosate readily with equimolar sodium nitrite in acetic acid, to afford the corresponding oximinoacetoacetate esters. A dissolving-zinc reduction of these in acetic acid in the presence of ketoesters or beta-diketones constitute the Knorr pyrrole synthesis, useful for the preparation of porphyrin
Porphyrins ( ) are heterocyclic, macrocyclic, organic compounds, composed of four modified pyrrole subunits interconnected at their α carbon atoms via methine bridges (). In vertebrates, an essential member of the porphyrin group is heme, w ...
s.
Another similarity to acetylacetone
Acetylacetone is an organic compound with the chemical formula . It is classified as a 1,3-diketone. It exists in equilibrium with a tautomer . The mixture is a colorless liquid. These tautomers interconvert so rapidly under most conditions that ...
, ethyl acetoacetate forms chelate complexes, such as and the Fe(III) derivative.
See also
Two ketals of ethyl acetoacetate are used in commercial fragrances.
Safety and environmental considerations
Ethyl acetoacetate has low toxicity to animals. It is highly biodegradable.[
]
References
External links
International Chemical Safety Card 1024
{{Authority control
Ethyl esters
Ester solvents
Flavors
Acetoacetate esters
Sweet-smelling chemicals