Ethyl acetoacetate

Ethyl acetoacetate
Names
	Preferred IUPAC name Ethyl 3-oxobutanoate
	Other names Acetoacetic acid ethyl ester; Ethyl acetylacetate; 3-Oxobutanoic acid ethyl ester;
Identifiers
CAS Number	141-97-9 ;
3D model (JSmol)	Interactive image;
ChEBI	CHEBI:4893;
ChEMBL	ChEMBL169176 ;
ChemSpider	13865426 ;
ECHA InfoCard	100.005.015
EC Number	205-516-1;
KEGG	C03500 ;
PubChem CID	8868;
RTECS number	AK5250000;
UNII	IZP61H3TB1 ;
UN number	1993
CompTox Dashboard (EPA)	DTXSID2027092 ;
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Properties
Chemical formula	C6H10O3
Molar mass	130.14 g/mol
Appearance	Colourless liquid
Odor	Fruit or rum
Density	1.021 g/cm3, liquid
Melting point	−45 °C (−49 °F; 228 K)
Boiling point	180.8 °C (357.4 °F; 453.9 K)
Solubility in water	2.86 g/100 ml (20 °C)
Acidity (pKa)	10.68 (in H2O); 14.2 (in DMSO);
Magnetic susceptibility (χ)	−71.67×10−6cm3/mol
Hazards
EU classification (DSD) (outdated)	Not listed
NFPA 704 (fire diamond)	2 2
Flash point	70 °C (158 °F; 343 K)
Related compounds
Related esters	Methyl acetoacetate; Ethyl acetate; Diethyl malonate;
Related compounds	Acetone; Acetylacetone; Diketene;
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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	Infobox references

The organic compound ethyl acetoacetate (EAA) is the ethyl ester of acetoacetic acid. It is a colorless liquid. It is widely used as a chemical intermediate in the production of a wide variety of compounds. It is used as a flavoring for food.

Preparation[]

Ethyl acetoacetate is produced industrially by treatment of diketene with ethanol.^[1]

The preparation of ethyl acetoacetate is a classic laboratory procedure.^[2] It is prepared via the Claisen condensation of ethyl acetate. Two moles of ethyl acetate condense to form one mole each of ethyl acetoacetate and ethanol.

Reactivity[]

Acidity[]

Ethyl acetoacetate is diprotic:^[3]

CH₃C(O)CH₂CO₂Et + NaH → CH₃C(O)CH(Na)CO₂Et + H₂

CH₃C(O)CH(Na)CO₂Et + BuLi → LiCH₂C(O)CH(Na)CO₂Et + BuH

Keto-enol tautomerism[]

Ethyl acetoacetate is subject to keto-enol tautomerism. In the neat liquid at 33 °C, the enol consists of 15% of the total.^[4]

Multicarbon building block[]

Ethyl acetoacetic acid is a building block in organic synthesis since the protons alpha to carbonyl groups are acidic, and the resulting carbanion undergoes nucleophilic substitution. Ethyl acetoacetate is often used in the acetoacetic ester synthesis similar to diethyl malonate in the malonic ester synthesis or the Knoevenagel condensation. A subsequent thermal decarboxylation is also possible.^[5]

The dianion of ethylacetoacetate 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:^[3]

LiCH₂C(O)CH(Na)CO₂Et + RX → RCH₂C(O)CH(Na)CO₂Et + LiX

Ligand[]

Similar to the behavior of acetylacetone, the enolate of ethyl acetoacetate can also serve as a bidentate ligand. For example, it forms purple coordination complexes with iron(III) salts:

Reduction[]

Reduction of ethyl acetoacetate gives ethyl 3-hydroxybutyrate.

Transesterification[]

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 porphyrins.

References[]

^ Riemenschneider, Wilhelm; Bolt, Hermann M. (2005). Esters, Organic. doi:10.1002/14356007.a09_565.pub2. ISBN 3527306730.
^ J. K. H. Inglis and K. C. Roberts (1926). "Ethyl Acetoacetate". Organic Syntheses. 6: 36. doi:10.15227/orgsyn.006.0036.
^ Jump up to: ^a ^b Jin, Yinghua; Roberts, Frank G.; Coates, Robert M. (2007). "Stereoselective Isoprenoid Chain Extension with Acetoacetate Dianion: [(E, E, E)-Geranylgeraniol from (E, E)-Farnesol". Organic Syntheses. 84: 43. doi:10.15227/orgsyn.084.0043.
^ Jane L. Burdett; Max T. Rogers (1964). "Keto-Enol Tautomerism in β-Dicarbonyls Studied by Nuclear Magnetic Resonance Spectroscopy. I. Proton Chemical Shifts and Equilibrium Constants of Pure Compounds". J. Am. Chem. Soc. 86: 2105–2109. doi:10.1021/ja01065a003.
^ Carey, Francis A. (2006). Organic Chemistry (Sixth ed.). New York, NY: McGraw-Hill. ISBN 0-07-111562-5.

External links[]

[1] Riemenschneider, Wilhelm; Bolt, Hermann M. (2005). Esters, Organic. doi:10.1002/14356007.a09_565.pub2. ISBN 3527306730.

[2] J. K. H. Inglis and K. C. Roberts (1926). "Ethyl Acetoacetate". Organic Syntheses. 6: 36. doi:10.15227/orgsyn.006.0036.

[RmC-3] Jump up to: ^a ^b Jin, Yinghua; Roberts, Frank G.; Coates, Robert M. (2007). "Stereoselective Isoprenoid Chain Extension with Acetoacetate Dianion: [(E, E, E)-Geranylgeraniol from (E, E)-Farnesol". Organic Syntheses. 84: 43. doi:10.15227/orgsyn.084.0043.

[4] Jane L. Burdett; Max T. Rogers (1964). "Keto-Enol Tautomerism in β-Dicarbonyls Studied by Nuclear Magnetic Resonance Spectroscopy. I. Proton Chemical Shifts and Equilibrium Constants of Pure Compounds". J. Am. Chem. Soc. 86: 2105–2109. doi:10.1021/ja01065a003.

[5] Carey, Francis A. (2006). Organic Chemistry (Sixth ed.). New York, NY: McGraw-Hill. ISBN 0-07-111562-5.

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