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15-Crown-5

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15-Crown-5

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15-Crown-5
Skeletal formula
Ball-and-stick model
Systematic name

1,4,7,10,13-Pentaoxacyclopentadecane[1]
Identifiers
CAS number 33100-27-5 YesY
PubChem 36336
ChemSpider 33416 YesY
EC number 251-379-6
MeSH 15-Crown-5
ChEBI CHEBI:324​01 N
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
Exact mass 220.131073750 g mol-1
Appearance Transparent liquid
Density 1.113 g cm-3 (at 20 °C)
Boiling point

116 °C, 389 K, 241 °F (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
NFPA 704.svg
1
2
0
Flash point 113 °C
 N (verify) (what is: YesY/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
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.

Contents

Chemistry

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 a 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

References

  1. ^ "15-crown-5 - Compound Summary". PubChem Compound. USA: National Center for Biotechnology Information. 16 September 2004. Identification and Related Records. http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=36336&loc=ec_rcs. Retrieved 11 October 2011. 
  2. ^ Takeda, Y., et al. (1998). "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. http://www.journalarchive.jst.go.jp/english/jnlabstract_en.php?cdjournal=bcsj1926&cdvol=61&noissue=3&startpage=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. http://www.rsc.org/publishing/journals/CC/article.asp?doi=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". http://www.uni-stuttgart.de/ochem/02/poster/200603%20Sauer.pdf. 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. http://infoscience.epfl.ch/record/52153. 
  7. ^ Fedorova, O.A., et al. (2005). "Facile synthesis of novel styryl ligands containing a 15-crown-5 ether moiety". Arkivoc xv: 12–24. http://www.arkat-usa.org/get-file/19080/. 

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Crown ether
Stability constants of complexes