18-Crown-6
| 18-Crown-6 | |
|---|---|
| Skeletal formula | |
| Ball-and-stick model | |
| 1,4,7,10,13,16-hexaoxacyclooctadecane | |
| style="background: #F8EABA; text-align: center;" colspan="2" | Identifiers | |
| CAS number | 17455-13-9 
|
| PubChem | 28557 |
| ChemSpider | 26563 |
| SMILES | Script error: No such module "collapsible list". |
| InChI | Script error: No such module "collapsible list". |
| InChI key | XEZNGIUYQVAUSS-UHFFFAOYAP |
| style="background: #F8EABA; text-align: center;" colspan="2" | Properties | |
| Molecular formula | C12H24O6 |
| Molar mass | 264.122 g/mol |
| Density | 1.237 g/cm³ |
| Melting point |
37-40 °C |
| Boiling point |
116 °C (0.2 Torr) |
| style="background: #F8EABA; text-align: center;" colspan="2" | Related compounds | |
| Related compounds | Dibenzo-18-crown-6 Triglyme |
 (what is this?) (verify)Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) | |
| Infobox references | |
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.
Synthesis
This compound can be prepared by a modified Williamson ether synthesis[1] as well as the oligomerization of ethylene oxide in the presence of a templating cation.
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.[1] 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.
Applications
Crown ethers are useful as phase transfer catalysts.[2] 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.
Related compounds
A related and generally superior complexant for alkali metal cations is dibenzo-18-crown-6.
References
- ↑ 1.0 1.1 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
|title=(help) - ↑ 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
External links
fi:18-kruunu-6 pt:18-Coroa-6 uk:18-Краун-6 zh:18-冠-6
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