1,3-Cyclohexanedione

1,3-Cyclohexanedione
Names
	Preferred IUPAC name Cyclohexane-1,3-dione
	Other names CHD, dihydroresorcinol
Identifiers
CAS Number	504-02-9;
3D model (JSmol)	Interactive image;
Beilstein Reference	385888
ChEBI	CHEBI:17766;
ChEMBL	ChEMBL363919;
ChemSpider	10004;
ECHA InfoCard	100.007.255
EC Number	207-980-0;
Gmelin Reference	200899
KEGG	C01066;
PubChem CID	10434;
UNII	6UK3D2BXJT;
CompTox Dashboard (EPA)	DTXSID1044433 ;
	InChI InChI=1S/C6H8O2/c7-5-2-1-3-6(8)4-5/h1-4H2 Key: HJSLFCCWAKVHIW-UHFFFAOYSA-N;
	SMILES C1CC(=O)CC(=O)C1;
Properties
Chemical formula	C6H8O2
Molar mass	112.128 g·mol−1
Appearance	Colorless or white solid
Density	1.0861 g/cm3
Melting point	105.5 °C (221.9 °F; 378.6 K)
Acidity (pKa)	5.20 (H2O)
Hazards
	GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H302, H318, H412
Precautionary statements	P264, P270, P273, P280, P301+P312, P305+P351+P338, P310, P330, P501
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

1,3-Cyclohexanedione is an organic compound with the formula (CH₂)₄(CO)₂. It is one of three isomeric cyclohexanediones. It is a colorless compound that occurs naturally. It is the substrate for cyclohexanedione hydrolase. The compound exists mainly as the enol tautomer.^[2]

Synthesis, structure, and reactivity

1,3-Cyclohexanedione is produced by semi-hydrogenation of resorcinol:^[3]^[4]

C₆H₄(OH)₂ + H₂ → C₆H₈O₂

1,3-Cyclohexanedione exists in solution predominantly as the enol tautomer.

It reacts under acid catalysis with alcohols to 3-alkoxyenones.^[2] Its pK_a is 5.26. Treatment of the sodium salt of the enolate with methyl iodide gives 2-methyl-1,3-cyclohexanedione, which also exists predominantly as the enol.^[4]

Derivatives

Dimedone (5,5-dimethyl-1,3-cyclohexanedione) is a well established reagent.^[5]

Several herbicides against grasses are formal derivatives of 1,3-cyclohexanedione. Examples of commercial products include cycloxydim, clethodim, tralkoxydim, butroxydim, profoxydim, and mesotrione.^[6]

References

^ Terasawa, Tadao; Okada, Toshihiko (1977). "Novel heterocyclic synthons. Synthesis and properties of thia- and oxacyclohexane-3,5-diones". J. Org. Chem. 42 (7): 1163–1169. doi:10.1021/jo00427a014.
^ ^a ^b Guppi, Sanjeeva Rao; O'Doherty, George A. (2008). "1,3-Cyclohexadiene". E-EROS Encyclopedia of Reagents for Organic Synthesis. doi:10.1002/047084289X.rn00921. ISBN 978-0471936237.
^ Thompson, R. B. (1947). "Dihydroresorcinol". Org. Synth. 27: 21. doi:10.15227/orgsyn.027.0021.
^ ^a ^b Mekler, A. B.; Ramachandran, S.; Swaminathan, S.; Newman, Melvin S. (1961). "Methyl-1,3-Cyclohexanedione". Org. Synth. 41: 56. doi:10.15227/orgsyn.041.0056.
^ Strittmatter, Harald; Hildbrand, Stefan; Pollak, Peter (2007). "Malonic Acid and Derivatives". Ullmann's Encyclopedia of Industrial Chemistry. doi:10.1002/14356007.a16_063.pub2. ISBN 978-3527306732.
^ Keith G. Watson (2011). "Cyclohexane-1,3-dione Oxime Ether Grass-Specific Herbicides and the Discovery of Butroxydim". Aust. J. Chem. 64 (4): 367–372. doi:10.1071/CH10366.

[1] Terasawa, Tadao; Okada, Toshihiko (1977). "Novel heterocyclic synthons. Synthesis and properties of thia- and oxacyclohexane-3,5-diones". J. Org. Chem. 42 (7): 1163–1169. doi:10.1021/jo00427a014.

[Eros-2] Guppi, Sanjeeva Rao; O'Doherty, George A. (2008). "1,3-Cyclohexadiene". E-EROS Encyclopedia of Reagents for Organic Synthesis. doi:10.1002/047084289X.rn00921. ISBN 978-0471936237.

[3] Thompson, R. B. (1947). "Dihydroresorcinol". Org. Synth. 27: 21. doi:10.15227/orgsyn.027.0021.

[OS-4] Mekler, A. B.; Ramachandran, S.; Swaminathan, S.; Newman, Melvin S. (1961). "Methyl-1,3-Cyclohexanedione". Org. Synth. 41: 56. doi:10.15227/orgsyn.041.0056.

[UllMal-5] Strittmatter, Harald; Hildbrand, Stefan; Pollak, Peter (2007). "Malonic Acid and Derivatives". Ullmann's Encyclopedia of Industrial Chemistry. doi:10.1002/14356007.a16_063.pub2. ISBN 978-3527306732.

[6] Keith G. Watson (2011). "Cyclohexane-1,3-dione Oxime Ether Grass-Specific Herbicides and the Discovery of Butroxydim". Aust. J. Chem. 64 (4): 367–372. doi:10.1071/CH10366.

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