15-Crown-5

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15-Crown-5
Skeletal formula
Ball-and-stick model
Identifiers
CAS number 33100-27-5 YesY
PubChem 36336
ChemSpider 33416 YesY
EC number 251-379-6
MeSH 15-Crown-5
ChEBI CHEBI:32401 YesY
ChEMBL CHEMBL156289 YesY
RTECS number SB0200000
Beilstein Reference 1618144
Gmelin Reference 3897
Jmol-3D images Image 1
Properties
Molecular formula C10H20O5
Molar mass 220.26 g mol−1
Appearance Clear, colorless liquid
Density 1.113 g cm-3 (at 20 °C)
Boiling point 116 °C (241 °F; 389 K) at 240 Pa
log P -0.639
Refractive index (nD) 1.465
Thermochemistry
Std enthalpy of
formation
ΔfHo298
-881.1--877.1 kJ mol-1
Std enthalpy of
combustion
ΔcHo298
-5.9157--5.9129 MJ mol-1
Hazards
MSDS msds.chem.ox.ac.uk
GHS pictograms The exclamation-mark pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)
GHS signal word WARNING
GHS hazard statements H302, H315, H319
GHS precautionary statements P305+351+338
EU classification Harmful Xn
R-phrases R22, R36/38
S-phrases S26
NFPA 704
Flammability code 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g., canola oil Health code 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g., chloroform Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored diamond
Flash point 113 °C (235 °F; 386 K)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 YesY (verify) (what is: YesY/N?)
Infobox references

15-Crown-5 is a crown ether with the formula (C2H4O)5. It is a cyclic pentamer of ethylene oxide that forms 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.

Properties[edit]

Analogous to 18-crown-6, 15-crown-5 bind 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 includes Co(ClO4)2, Ni(ClO4)2, Cu(ClO4)2, and Zn(ClO4)2. Seven coordinate species are most common for transition metal ions complexes of 15-crown-5, with the crown ether occupying the equatorial plane, along with 2 axial aqua ligands.[4]

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

15-crown-5 have also been used to isolate salts of oxonium ions. For example, from a solution of tetrachloroauric acid, the oxonium ion [H7O3]+ have 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).[4]

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

A derivative of 15-crown-5, benzo-15-crown-5, have been used to produce anionic complexes of carbido ligands as their [K(benzo-15-crown-5)2]+ salts:[4]

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

See also[edit]

References[edit]

  1. ^ "15-crown-5 - Compound Summary". PubChem Compound. USA: National Center for Biotechnology Information. 16 September 2004. Identification and Related Records. Retrieved 11 October 2011. 
  2. ^ Takeda, Y., et al. (1988). "A Conductance Study of 1:1 Complexes of 15-Crown-5, 16-Crown-5, and Benzo-15-crown-5 with Alkali Metal Ions in Nonaqueous Solvents". Bulletin of the Chemical Society of Japan 61 (3): 627–632. doi:10.1246/bcsj.61.627. 
  3. ^ Chen, Chun-Yen, et al. (2006). "Potassium ion recognition by 15-crown-5 functionalized CdSe/ZnS quantum dots in H2O". Chem. Comm. (3): 263–265. doi:10.1039/B512677K. 
  4. ^ a b c Jonathan W. Steed; Jerry L. Atwood (2009). Supramolecular Chemistry, 2nd edition. Wiley. ISBN 978-0-470-51233-3. 

Further reading[edit]

External links[edit]