15-Crown-5

Chemical compound From Wikipedia, the free encyclopedia

15-Crown-5 is a crown ether with the formula (C2H4O)5. It is a cyclic pentamer of ethylene oxide that forms a complex with various cations, including sodium (Na+)[2] and potassium (K+);[3] however, it is complementary to Na+ and thus has a higher selectivity for Na+ ions.

Quick facts Names, Identifiers ...
15-Crown-5
Skeletal formula
Ball-and-stick model
Names
Preferred IUPAC name
1,4,7,10,13-Pentaoxacyclopentadecane[1]
Identifiers
3D model (JSmol)
1618144
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.046.694 Edit this at Wikidata
EC Number
  • 251-379-6
3897
MeSH 15-Crown-5
RTECS number
  • SB0200000
  • InChI=1S/C10H20O5/c1-2-12-5-6-14-9-10-15-8-7-13-4-3-11-1/h1-10H2 checkY
    Key: VFTFKUDGYRBSAL-UHFFFAOYSA-N checkY
  • InChI=1/C10H20O5/c1-2-12-5-6-14-9-10-15-8-7-13-4-3-11-1/h1-10H2
    Key: VFTFKUDGYRBSAL-UHFFFAOYAH
  • C1COCCOCCOCCOCCO1
Properties
C10H20O5
Molar mass 220.265 g·mol−1
Appearance Clear, colorless liquid
Density 1.113 g cm−3 (at 20 Â°C)
Boiling point 93–96 Â°C (199–205 Â°F; 366–369 K) at 0.05 mmHg
log P −0.639
1.465
Thermochemistry
Std enthalpy of
formation (ΔfH⦵298)
 −881.1 to −877.1 kJ mol−1
Std enthalpy of
combustion (ΔcH⦵298)
 −5.9157 to −5.9129 MJ mol−1
Hazards
GHS labelling:
GHS07: Exclamation mark
Warning
H302, H315, H319
P305+P351+P338
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformFlammability 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g. canola oilInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
2
1
0
Flash point 113 Â°C (235 Â°F; 386 K)
Safety data sheet (SDS) msds.chem.ox.ac.uk
Except where otherwise noted, data are given for materials in their standard state (at 25 Â°C [77 Â°F], 100 kPa).
checkY verify (what is checkY☒N ?)
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Synthesis

15-Crown-5 can be synthesized using a modified Williamson ether synthesis:[4]

(CH2OCH2CH2Cl)2 + O(CH2CH2OH)2 + 2 NaOH → (CH2CH2O)5 + 2 NaCl + 2 H2O

It also forms from the cyclic oligomerization of ethylene oxide in the presence of gaseous boron trifluoride.[5]

Properties

Analogous to 18-crown-6, 15-crown-5 binds to sodium ions. Thus, when treated with this complexing agent, sodium salts often become soluble in organic solvents.

First-row transition metal dications fit snugly inside the cavity of 15-crown-5. They are too small to be included in 18-crown-6. The binding of transition metal cations results in multiple hydrogen-bonded interactions from both equatorial and axial aqua ligands, such that highly crystalline solid-state supramolecular polymers can be isolated. Metal salts isolated in this form include Co(ClO4)2, Ni(ClO4)2, Cu(ClO4)2, and Zn(ClO4)2. Seven coordinate species are most common for transition metal complexes of 15-crown-5, with the crown ether occupying the equatorial plane, along with 2 axial aqua ligands.[6]

The structure of the complex [Co(15-crown-5)(H2O)2]2+.

15-crown-5 has also been used to isolate salts of oxonium ions. For example, from a solution of tetrachloroauric acid, the oxonium ion [H7O3]+ has been isolated as the salt [(H7O3)(15-crown-5)2][AuCl4]. Neutron diffraction studies revealed a sandwich structure, which shows a chain of water with remarkably long O-H bond (1.12 Å) in the acidic proton, but with a very short OH•••O distance (1.32 Å).[6]

Structure of [(H7O3)(15-crown-5)2]+ ion

A derivative of 15-crown-5, benzo-15-crown-5, has been used to produce anionic complexes of carbido ligands as their [K(benzo-15-crown-5)2]+ salts:[6]

(Ar2N)3MoCH + KCH2Ph + 2 (15-crown-5) → [K(15-crown-5)2]+[(Ar2N)3MoC]− + CH3Ph

See also

References

Further reading

External links

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