|style="background: #F8EABA; text-align: center;" colspan="2" | Identifiers|
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|style="background: #F8EABA; text-align: center;" colspan="2" | Properties|
|Molar mass||264.122 g/mol|
116 °C (0.2 Torr)
|style="background: #F8EABA; text-align: center;" colspan="2" | Related compounds|
|Related compounds|| Dibenzo-18-crown-6|
| (what is this?) |
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
18-Crown-6 is an organic compound with the formula [C2H4O]6 and the IUPAC name of 1,4,7,10,13,16-hexaoxacyclooctadecane. The compound is a crown ether. Crown ethers coordinate some metal cations in their central cavity; 18-crown-6 displays a particular affinity for potassium cations. The synthesis of the crown ethers led to the Nobel Prize in Chemistry to Charles J. Pedersen.
It can be purified by distillation, where its tendency to supercool becomes evident. 18-Crown-6 can also be purified by precipitation with acetonitrile, with which it initially forms an insoluble complex. The acetonitrile may be removed in vacuo to obtain the desired compound. Rigorously dry material can be made by dissolving the compound in THF followed by the addition of NaK to give [K(18-crown-6)]Na, an alkalide salt.
Crown ethers are useful as phase transfer catalysts. In the presence of 18-crown-6 potassium permanganate dissolves in benzene, although this application is eclipsed by the use of quaternary ammonium/phosphonium salts.
Using 18-crown-6, potassium acetate is a more powerful nucleophile in organic solvents.
A related and generally superior complexant for alkali metal cations is dibenzo-18-crown-6.
- George W. Gokel, Donald J. Cram, Charles L. Liotta, Henry P. Harris, and Fred L. Cook (1988), "18-Crown-6", Org. Synth.; Coll. Vol., 6: 301 Missing or empty
- Liotta, C. L.; Berknerin, J. "18-Crown-6" in Encyclopedia of Reagents for Organic Synthesis (Ed: L. Paquette) 2004, J. Wiley & Sons, New York. doi:10.1002/047084289X.rc261
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