Dimedone

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Dimedone
Dimedone.png
Dimedone-3D-balls.png
Names
IUPAC name
5,5-Dimethylcyclohexane-1,3-dione
Other names
Cyclomethone,
5,5-dimethyl-1,3-cyclohexanedione,
Dimethyldihydroresorcinol,
Methone
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.004.369
Properties
C8H12O2
Molar mass 140.17968
Appearance Yellow crystals
Melting point 147 to 150 °C (297 to 302 °F; 420 to 423 K) (decomposes)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Dimedone is a cyclic diketone used in organic chemistry to determine whether a compound contains an aldehyde group. Cyclohexanediones in general can be used as catalysts in the formation of transition-metal complexes. Other uses include applications in colorimetry, crystallography, luminescence and spectrophotometric analysis. It can also be used for chemistry involving organic compounds of low electrical resistance.

Synthesis[edit]

Dimedone is prepared from mesityl oxide and dimethyl malonate.[1]

Physical properties[edit]

Dimedone usually comes in the form of white crystals. It is stable under ambient conditions and soluble in water, as well as ethanol and methanol. It has a melting point range of 147–150 °C (420–423 K).

Tautomerism[edit]

Dimedone is in equilibrium with its tautomer in solution — in a 2:1 keto to enol ratio in chloroform.[2]

Diagram of tautomeric equilibrium of dimedone

Crystalline dimedone contains chains of molecules, in the enol form, linked by hydrogen bonds:[3]

Ball-and-stick model of a hydrogen-bonded dimedone chain, as found in the crystal structure

References[edit]

  1. ^ R. L. Shriner and H. R. Todd (1935). "5,5-dimethyl-1,3-cyclohexanedione". Organic Syntheses. 15: 16. doi:10.1002/0471264180.os015.06. 
  2. ^ Clayden, Jonathan; Greeves, Nick; Warren, Stuart; Wothers, Peter (2001). Organic Chemistry (1st ed.). Oxford University Press. p. 532. ISBN 978-0-19-850346-0. 
  3. ^ M. Bolte and M. Scholtyssik (October 1997). "Dimedone at 133K". Acta Crystallogr. C. 53 (10): IUC9700013. doi:10.1107/S0108270197099423.