Cyclopentadienone

Cyclopentadienone is an organic compound with molecular formula C₅H₄O. The parent cyclopentadienone is rarely encountered, because it rapidly dimerizes.^[1] Many substituted derivatives are known, notably tetraphenylcyclopentadienone. Such compounds are used as ligands in organometallic chemistry.^[2]

The Knölker complex, derived from a substituted cyclopentadienone, is a catalyst for transfer hydrogenation.^[3]

Cyclopentadienone

Names
Preferred IUPAC name Cyclopenta-2,4-dien-1-one
Identifiers
CAS Number	13177-38-3
3D model (JSmol)	Interactive image
ChemSpider	122931
PubChem CID	139405
CompTox Dashboard (EPA)	DTXSID80157203
InChI InChI=1S/C5H4O/c6-5-3-1-2-4-5/h1-4H Key: FQQOMPOPYZIROF-UHFFFAOYSA-N InChI=1/C5H4O/c6-5-3-1-2-4-5/h1-4H Key: FQQOMPOPYZIROF-UHFFFAOYAD
SMILES C1=CC(=O)C=C1
Properties
Chemical formula	C5H4O
Molar mass	80.086 g·mol−1
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Preparation

Cyclopentadienone can be generated by the photolysis or pyrolysis of various substances (e.g. 1,2-benzoquinone^[4]), and then isolated in an argon matrix at 10 K (−263 °C). It dimerizes readily upon thawing the matrix at 38 K (−235 °C).^[5][6]

See also

• Dienone

References

1. Ogliaruso, Michael A.; Romanelli, Michael G.; Becker, Ernest I. (1965). "Chemistry of Cyclopentadienones". Chemical Reviews. 65: 261–367. doi:10.1021/cr60235a001.
2. Quintard, A.; Rodriguez, J. (2014). "Iron Cyclopentadienone Complexes: Discovery, Properties, and Catalytic Reactivity". Angewandte Chemie International Edition. 53: 4044–4055. doi:10.1002/anie.201310788.
3. Casey, Charles P.; Guan, Hairong (2007). "An Efficient and Chemoselective Iron Catalyst for the Hydrogenation of Ketones". Journal of the American Chemical Society. 129 (18): 5816–5817. doi:10.1021/ja071159f. PMID 17439131.
4. Brown, Roger F. C. (2012). Pyrolytic Methods in Organic Chemistry: Application of Flow and Flash Vacuum Techniques. Elsevier. p. 173. ISBN 978-0-323-15417-8.
5. Maier, Günther; Franz, Lothar Hermann; Hartan, Hans-Georg; Lanz, Klaus; Reisenauer, Hans Peter (1985). "Kleine Ringe. 54. Cyclopentadienon" [Small rings. 54. Cyclopentadienone]. Chemische Berichte (in German). 118 (8): 3196–3204. doi:10.1002/cber.19851180819.
6. Horspool, William M.; Lenci, Francesco. CRC Handbook of Organic Photochemistry and Photobiology. Vol. 1–2 (2nd ed.). p. 12-8. ISBN 978-0-203-49590-2.