1,3-Cyclohexanedione

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]

1,3-Cyclohexanedione
Names
Preferred IUPAC name
Cyclohexane-1,3-dione
Other names
CHD, dihydroresorcinol
Identifiers
3D model (JSmol)
385888
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.007.255
EC Number
  • 207-980-0
200899
KEGG
UNII
Properties
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)[1]
Hazards
GHS pictograms
GHS Signal word Danger
H302, H318, H412
P264, P270, P273, P280, P301+312, P305+351+338, 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

Synthesis, structure, and reactivity

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

C6H4(OH)2 + H2 → C6H8O2

1,3-Cyclohexanedione exists in solution as the enol. It reacts under acid catalysis with alcohols to 3-alkoxyenones.[2]

Enolization of 1,3-cyclohexanedione.

Its pKa is 5.26. Treatment of the sodium salt of the enolate with methyl iodide gives 2-methyl-1,3-cyclohexanedione, which despite the name, also exists predominantly as the enol.[3]

Derivatives

Dimedone, 5,5-dimethyl-1,3-cyclohexanedione is a well established reagent.

Several herbicides are formal derivatives of 1,3-cyclohexanedione. Examples of commercial products include cycloxydim, clethodim, tralkoxydim, butroxydim, profoxydim, mesotrione and quizalofop-P-ethyl.[4]

References

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