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    15-Crown-5

    From Wikipedia - Reading time: 5 min
    15-Crown-5
    Skeletal formula
    Ball-and-stick model
    Names
    Preferred IUPAC name
    1,4,7,10,13-Pentaoxacyclopentadecane[1]
    Identifiers
    CAS Number
    3D model (JSmol)
    Beilstein Reference
    		 1618144
    ChEBI
    ChEMBL
    ChemSpider
    ECHA InfoCard 100.046.694 Edit this at Wikidata
    EC Number
    • 251-379-6
    Gmelin Reference
    		 3897
    MeSH 15-Crown-5
    PubChem CID
    RTECS number
    • SB0200000
    CompTox Dashboard (EPA)
    InChI
    • 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
    SMILES
    • C1COCCOCCOCCOCCO1
    Properties
    Chemical formula
    		 C10H20O5
    Molar mass 220.265 g·mol−1
    Appearance Clear, colorless liquid
    Density 1.113 g cm−3 (at 20 °C)
    Boiling point 93–96 °C (199–205 °F; 366–369 K) at 0.05 mmHg
    log P -0.639
    Refractive index (nD)
    		 1.465
    Thermochemistry
    Std enthalpy of
    formation (ΔfH⦵298)
    		 -881.1--877.1 kJ mol−1
    Std enthalpy of
    combustion (ΔcH⦵298)
    		 -5.9157--5.9129 MJ mol−1
    Hazards
    GHS labelling:
    Pictograms
    		 GHS07: Exclamation mark
    Signal word
    		 Warning
    Hazard statements
    		 H302, H315, H319
    Precautionary statements
    		 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 °C (235 °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 °C [77 °F], 100 kPa).
    checkY verify (what is checkY☒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.

    Synthesis[edit]

    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[edit]

    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[edit]

    • Host guest chemistry
    • Phase transfer catalyst

    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. PMID 16391728.
    4. ^ 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.
    5. ^ Liotta, Charles L.; Berkner, Joachim (2001), "15-Crown-5", Encyclopedia of Reagents for Organic Synthesis, Chichester, UK: John Wiley & Sons, Ltd, doi:10.1002/047084289x.rc263, ISBN 978-0-471-93623-7
    6. ^ 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]

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