12-Crown-4
Chemical compound
From Wikipedia, the free encyclopedia
12-Crown-4, also called 1,4,7,10-tetraoxacyclododecane and lithium ionophore V, is a crown ether with the formula C8H16O4. It is a cyclic tetramer of ethylene oxide which is specific for the lithium cation.
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| Names | |||
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| Preferred IUPAC name
1,4,7,10-Tetraoxacyclododecane | |||
| Other names
12-crown-4, Lithium Ionophore V | |||
| Identifiers | |||
3D model (JSmol) |
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| 1363064 | |||
| ChEBI | |||
| ChemSpider | |||
| ECHA InfoCard | 100.005.488 | ||
| EC Number |
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| 3287 | |||
PubChem CID |
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| UNII | |||
CompTox Dashboard (EPA) |
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| Properties | |||
| C8H16O4 | |||
| Molar mass | 176.21 | ||
| Density | 1.089 g/mL at 25 °C | ||
| Melting point | 16 °C | ||
| Boiling point | 61-70 °C/0.5 mm Hg | ||
| Miscible | |||
| Hazards | |||
| Flash point | 113 °C (235 °F; 386 K) | ||
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Synthesis
12-Crown-4 can be synthesized using a modified Williamson ether synthesis, using LiClO4 as a templating cation:[1]
- (CH2OCH2CH2Cl)2 + (CH2OH)2 + 2 NaOH → (CH2CH2O)4 + 2 NaCl + 2 H2O
It also forms from the cyclic oligomerization of ethylene oxide in the presence of gaseous boron trifluoride.[2]
Properties
lithium-cation-from-xtal-3D-balls-B.png)
Like other crown ethers, 12-crown-4 complexes with alkali metal cations. The cavity diameter of 1.2-1.5 Å gives it a high selectivity towards the lithium cation (ionic diameter 1.36 Å)[2]
Its point group is S4. The dipole moment of 12-crown-4 varies with solvent and temperature. At 25 °C, the dipole moment of 12-crown-4 was determined as 2.33 ± 0.03 D in cyclohexane and 2.46 ± 0.01 D in benzene.[3]