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 C10H20O5. It is a cyclic pentamer of ethylene oxide that has been shown to 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.

Chemistry[edit]

Analogous to 18-crown-6, 15-crown-5 can bind to sodium ions, making the ionic compounds soluble in hydrophobic phases.

However, 15-crown-5 allows the first-row transition metal cations to fit snugly inside the cavity of 15-crown-5, which is 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 were 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]

Cobalt(II) complex with 15-crown-5

15-crown-5 have also been used to isolate some specific, intriguing 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 carbide complexes. The first step of this method is to synthesize an acetylide complex from the corresponding metal carbonyl, followed by abstracting the acidic proton in the acetylide with a strong base. Benzo-15-crown-6 is then applied to sequester the K+ counter ions to give the free carbide complex.[4]

Scheme for synthesizing a carbide complex higher resol

As a functional group, research has been conducted to probe its application in liquid crystalline studies,[5] ion-selective membranes,[6] chromo- and fluoroionophores.[7]

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. 
  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. 
  5. ^ "Mesogenic Properties of 15-Crown-5-Ether - Derivatives". Retrieved 2008-11-19. [dead link]
  6. ^ Klok, H.A., et al. (1997). "Novel benzo-15-crown-5 functionalized α-olefin/CO terpolymers for membrane applications". Macromolecular Chemistry and Physics 198 (9): 2759–2768. doi:10.1002/macp.1997.021980908. 
  7. ^ Fedorova, O.A., et al. (2005). "Facile synthesis of novel styryl ligands containing a 15-crown-5 ether moiety". Arkivoc xv: 12–24. 

External links[edit]