Diketene

Diketene
IUPAC name 4-methylideneoxetan-2-one
Other names γ-methylenebutyrolactone
Identifiers
CAS number	674-82-8 Y
ChemSpider	12140 Y
Jmol-3D images	Image 1
SMILES O=C1OC(=C)C1
InChI InChI=1S/C4H4O2/c1-3-2-4(5)6-3/h1-2H2 Y Key: WASQWSOJHCZDFK-UHFFFAOYSA-N Y InChI=1/C4H4O2/c1-3-2-4(5)6-3/h1-2H2 Key: WASQWSOJHCZDFK-UHFFFAOYAM
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
Y (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Diketene is an organic compound formed by dimerization of 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.