Ethyl acetoacetate
Skeletal formula of ethyl acetoacetate
Space-filling model of the ethyl acetoacetate molecule
Names
Preferred IUPAC name
Ethyl 3-oxobutanoate
Other names
  • Acetoacetic acid ethyl ester
  • Ethyl acetylacetate
  • 3-Oxobutanoic acid ethyl ester
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.005.015 Edit this at Wikidata
EC Number
  • 205-516-1
KEGG
RTECS number
  • AK5250000
UNII
UN number 1993
  • InChI=1S/C6H10O3/c1-3-9-6(8)4-5(2)7/h3-4H2,1-2H3 checkY
    Key: XYIBRDXRRQCHLP-UHFFFAOYSA-N checkY
  • InChI=1/C6H10O3/c1-3-9-6(8)4-5(2)7/h3-4H2,1-2H3
    Key: XYIBRDXRRQCHLP-UHFFFAOYAP
  • CCOC(=O)CC(=O)C
Properties
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)
2.86 g/100 ml (20 °C)
Acidity (pKa)
  • 10.68 (in H2O)
  • 14.2 (in DMSO)
−71.67×10−6cm3/mol
Hazards
GHS labelling:[1]
GHS07: Exclamation mark
Warning
H319
P305+P351+P338
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformFlammability 2: Must be moderately heated or exposed to relatively high ambient temperature before ignition can occur. Flash point between 38 and 93 °C (100 and 200 °F). E.g. diesel fuelInstability (yellow): no hazard codeSpecial hazards (white): no code
2
2
Flash point 70 °C (158 °F; 343 K)
Related compounds
Related esters
Related compounds
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
checkY verify (what is checkY☒N ?)

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.[not verified in body]

Preparation

At large scale, ethyl acetoacetate is industrially produced by treatment of diketene with ethanol.[2]

The small scale preparation of ethyl acetoacetate is a classic laboratory procedure.[3] It involves Claisen condensation of ethyl acetate. Two moles of ethyl acetate condense to form one mole each of ethyl acetoacetate and ethanol.

Preparation of ethyl acetoacetate
Preparation of ethyl acetoacetate

Reactivity

Acidity

Ethyl acetoacetate is diprotic:[4]

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.[5]

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.[6]

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:[4]

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.

See also

References

  1. ^ Record in the GESTIS Substance Database of the Institute for Occupational Safety and Health, accessed on 2021-12-19.
  2. ^ Riemenschneider, Wilhelm; Bolt, Hermann M. (2005). Esters, Organic. doi:10.1002/14356007.a09_565.pub2. ISBN 3527306730.
  3. ^ J. K. H. Inglis and K. C. Roberts (1926). "Ethyl Acetoacetate". Organic Syntheses. 6: 36. doi:10.15227/orgsyn.006.0036.
  4. ^ 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.
  5. ^ 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.
  6. ^ Carey, Francis A. (2006). Organic Chemistry (Sixth ed.). New York, NY: McGraw-Hill. ISBN 0-07-111562-5.

External links

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