12-Crown-4

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.

12-Crown-4
Skeletal formula of 12-crown-4
Ball-and-stick model of the 12-Crown-4 molecule
Names
Preferred IUPAC name
1,4,7,10-Tetraoxacyclododecane
Other names
12-crown-4, Lithium Ionophore V
Identifiers
3D model (JSmol)
1363064
ChEBI
ChemSpider
ECHA InfoCard 100.005.488
EC Number
  • 206-036-5
3287
UNII
  • InChI=1S/C8H16O4/c1-2-10-5-6-12-8-7-11-4-3-9-1/h1-8H2 checkY
    Key: XQQZRZQVBFHBHL-UHFFFAOYSA-N checkY
  • InChI=1/C8H16O4/c1-2-10-5-6-12-8-7-11-4-3-9-1/h1-8H2
    Key: XQQZRZQVBFHBHL-UHFFFAOYAA
  • O1CCOCCOCCOCC1
  • C1COCCOCCOCCO1
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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Infobox references

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
Ball-and-stick model of the bis(12-crown-4)lithium cation

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]

References
  1. Cook, Fred L.; Caruso, Thomas C.; Byrne, Michael P.; Bowers, Chauncey W.; Speck, Don H.; Liotta, Charles L. (1974). "Facile syntheses of 12-crown-4 and 15-crown-5". Tetrahedron Letters. 15 (46): 4029–4032. doi:10.1016/S0040-4039(01)92075-1.
  2. Liotta, Charles L.; Berkner, Joachim (2001), "12-Crown-4", Encyclopedia of Reagents for Organic Synthesis, Chichester, UK: John Wiley & Sons, Ltd, doi:10.1002/047084289X.rc262, ISBN 978-0-471-93623-7
  3. Caswell, Lyman R.; Savannunt, Diana S. (January 1988). "Temperature and solvent effects on the experimental dipole moments of three crown ethers". Journal of Heterocyclic Chemistry. 25 (1): 73–79. doi:10.1002/jhet.5570250111.
  • Sigma-Aldrich Handbook of Fine Chemicals, 2007, page 768.
  • Sigma-Aldrich Cyclic tetramer of ethylene oxide which is specific for the lithium cation. 98%, 2018

See also
  • Crown ether
  • Cyclen, a similar molecule with N atoms (aza groups) instead of O atoms (ethers)
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