Diketene

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Diketene
Identifiers
CAS number 674-82-8 YesY
ChemSpider 12140 YesY
Jmol-3D images Image 1
Properties
Molecular formula C4H4O2
Molar mass 84.08 g mol−1
Density 1.09 g cm−3
Melting point −7 °C
Boiling point 127 °C
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Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Infobox references

Diketene is an organic compound formed by dimerization of ethenone (ketene). Diketene is a member of the oxetane family. It is used as a chemical reagent in organic chemistry.[1] It is a colorless liquid and heating regenerates the ketene monomer. Alkylated ketenes also dimerize with ease and form substituted diketenes.

Diketene readily hydrolyses in water forming acetoacetic acid, its half-life in pure water is approximately 45 minutes a 25 °C at 2<pH<7.[2] Diketene also reacts with alcohols and amines to the corresponding acetoacetic acid derivatives. An example is the reaction with 2-aminoindane:[3]

Despite its high reactivity as an alkylating agent, and unlike analogue β-lactones propiolactone and β-butyrolactone, diketene is inactive as a carcinogen, possibly due to the instability of its DNA adducts.[4]

Diketene is an important industrial intermediate used for the production of acetoacetate esters and amides as well as substituted 1-phenyl-3-methylpyrazolones. The latter are used in the manufacture of dyestuffs and pigments.[5]

Certain diketenes with two aliphatic chains, such as alkyl ketene dimer (AKD), are used industrially to improve hydrophobicity in paper.

References

This article incorporates information from the German Wikipedia.
  1. Beilstein E III/IV 17: 4297.
  2. Rafael Gómez-Bombarelli, Marina González-Pérez, María Teresa Pérez-Prior, José A. Manso, Emilio Calle and Julio Casado (2008). "Kinetic Study of the Neutral and Base Hydrolysis of Diketene". Phys. Org. Chem 22 (5): n/a. doi:10.1002/poc.1483. 
  3. Kiran Kumar Solingapuram Sai, Thomas M. Gilbert, and Douglas A. Klumpp (2007). "Knorr Cyclizations and Distonic Superelectrophiles". J. Org. Chem. 72 (25): 9761–9764. doi:10.1021/jo7013092. PMID 17999519. 
  4. Rafael Gómez-Bombarelli, Marina González-Pérez, María Teresa Pérez-Prior, José A. Manso, Emilio Calle and Julio Casado (2008). "Chemical Reactivity and Biological Activity of Diketene". Chem. Res. Toxicol. 21 (10): 1964–1969. doi:10.1021/tx800153j. PMID 18759502. 
  5. Ashford's Dictionary of Industrial Chemicals, Third Edition, 2011, pages 3241-2.
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