1,2-Cyclopentanedione

1,2-Cyclopentanedione
Names
	Preferred IUPAC name Cyclopentane-1,2-dione
Identifiers
CAS Number	3008-40-0 ;
3D model (JSmol)	Interactive image;
ChemSpider	492605;
ECHA InfoCard	100.308.427
PubChem CID	566657;
UNII	DQ8L4K1DLJ ;
CompTox Dashboard (EPA)	DTXSID60952490 ;
	InChI InChI=1S/C5H6O2/c6-4-2-1-3-5(4)7/h1-3H2 Key: CIISBNCSMVCNIP-UHFFFAOYSA-N;
	SMILES C1CC(=O)C(=O)C1;
Properties
Chemical formula	C5H6O2
Molar mass	98.101 g·mol−1
Appearance	colorless liquid
Density	1.371 g/cm3
Melting point	56 °C (133 °F; 329 K)
Boiling point	87–88 °C (189–190 °F; 360–361 K) (15 mm Hg)
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

1,2-Cyclopentanedione is the organic compound with the formula (CH₂)₃(CO)₂. It is one of two isomeric cyclopentanediones, the other being 1,3-cyclopentanedione. It was first prepared by base-induced condensation of di ethylglutarate with diethyloxalate, followed by hydrolysis of the resulting diketodiester followed by decarboxylation.^[1] The enol is predicted to be about 1-3 kcal/mol more stable than the diketo form.^[2] The enol structure has been confirmed by X-ray crystallography.^[3]

Structurally related to 1,2-cyclopentanedione is 2-hydroxy-3-methyl-2-cyclopenten-1-one is a flavor additive, also called cyclotene.

References

^ Hesse, Gerhard; Bücking, Eva (1949). "Die Synthese der Reduktinsäure (Synthesis of Reductic Acid)". Justus Liebigs Annalen der Chemie. 563: 31–37. doi:10.1002/jlac.19495630105.
^ Jana, Kalyanashis; Ganguly, Bishwajit (2018). "DFT Study to Explore the Importance of Ring Size and Effect of Solvents on the Keto–Enol Tautomerization Process of α- and β-Cyclodiones". ACS Omega. 3 (7): 8429–8439. doi:10.1021/acsomega.8b01008. PMC 6644555. PMID 31458971.
^ Gerrard, Juliet A.; Meade, Susie J.; Morris, Jonathan C.; Steel, Peter J. (2000). "Two crystalline modifications of 2-hydroxycyclopent-2-enone". Acta Crystallographica Section C: Crystal Structure Communications. 56 (10): 1251–1253. doi:10.1107/S0108270100009550. PMID 11025315.

[1] Hesse, Gerhard; Bücking, Eva (1949). "Die Synthese der Reduktinsäure (Synthesis of Reductic Acid)". Justus Liebigs Annalen der Chemie. 563: 31–37. doi:10.1002/jlac.19495630105.

[2] Jana, Kalyanashis; Ganguly, Bishwajit (2018). "DFT Study to Explore the Importance of Ring Size and Effect of Solvents on the Keto–Enol Tautomerization Process of α- and β-Cyclodiones". ACS Omega. 3 (7): 8429–8439. doi:10.1021/acsomega.8b01008. PMC 6644555. PMID 31458971.

[3] Gerrard, Juliet A.; Meade, Susie J.; Morris, Jonathan C.; Steel, Peter J. (2000). "Two crystalline modifications of 2-hydroxycyclopent-2-enone". Acta Crystallographica Section C: Crystal Structure Communications. 56 (10): 1251–1253. doi:10.1107/S0108270100009550. PMID 11025315.

[1]