|Jmol-3D images||Image 1|
|Molar mass||84.08 g mol−1|
|Density||1.09 g cm−3|
|Melting point||−7 °C|
|Boiling point||127 °C|
| (what is: / ?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Diketene is an organic compound with the formula (CH2CO)2. It is formed by dimerization of ketene (IUPAC name: ethenone). Diketene is a member of the oxetane family. It is used as a reagent in organic chemistry. It is a colorless liquid.
Ketene is generated by dehydrating acetic acid at 700–750 °C in the presence of triethyl phosphate as a catalyst or (in Switzerland and the CIS) by the thermolysis of acetone at 600–700 °C in the presence of carbon disulfide as a catalyst.
- CH3CO2H → H2C=C=O + H2O (ΔH = +147 kJ/mol)
- CH3COCH3 → H2C=C=O + CH4
Heating regenerates the ketene monomer:
- (CH2CO)2 2 CH2CO
Alkylated ketenes also dimerize with ease and form substituted diketenes.
At one time acetic anhydride was prepared by the reaction of ketene with acetic acid:
- H2C=C=O + CH3COOH → (CH3CO)2O (ΔH = −63 kJ/mol)
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. A typical reaction is:
- ArNH2 + (CH2CO)2 → ArNHC(O)CH2C(O)CH3
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.
- This article incorporates information from the German Wikipedia.
- Beilstein E III/IV 17: 4297.
- Arpe, Hans-Jürgen (2007-01-11), Industrielle organische Chemie: Bedeutende vor- und Zwischenprodukte (6th ed.), Weinheim: Wiley-VCH, pp. 200–1, ISBN 3-527-31540-3.
- 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.
- 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.
- Ashford's Dictionary of Industrial Chemicals, Third Edition, 2011, pages 3241-2.
- K. Hunger. W. Herbst "Pigments, Organic" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2012. doi:10.1002/14356007.a20_371
- 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.