1 / 17

Crown Ethers

Crown Ethers. Crown Ethers. structure cyclic polyethers derived from repeating —OCH 2 CH 2 — units properties form stable complexes with metal ions applications synthetic reactions involving anions. O. O. O. O. O. O. 18-Crown-6.

brianz
Download Presentation

Crown Ethers

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Crown Ethers

  2. Crown Ethers structurecyclic polyethers derived from repeating —OCH2CH2— units propertiesform stable complexes with metal ions applicationssynthetic reactions involving anions

  3. O O O O O O 18-Crown-6 negative charge concentrated in cavity inside the molecule

  4. O O O O O O 18-Crown-6 negative charge concentrated in cavity inside the molecule

  5. O O O O O O 18-Crown-6 forms stable Lewis acid/Lewis base complex with K+ K+

  6. O O O O O O 18-Crown-6 forms stable Lewis acid/Lewis base complex with K+ K+

  7. Ion-Complexing and Solubility K+F– not soluble in benzene

  8. O O O O O O Ion-Complexing and Solubility K+F– benzene add 18-crown-6

  9. O O O O O O O O O O O O Ion-Complexing and Solubility F– K+ benzene 18-crown-6 complex of K+ dissolves in benzene

  10. O O O O O O O O O O O O + F– Ion-Complexing and Solubility K+ benzene F– carried into benzene to preserve electroneutrality

  11. Application to organic synthesis Complexaton of K+ by 18-crown-6 "solubilizes" salt in benzene Anion of salt is in a relatively unsolvated state in benzene (sometimes referred to as a "naked anion") Unsolvated anion is very reactive Only catalytic quantities of 18-crown-6 are needed

  12. Polyether Antibiotics

  13. Example KF CH3(CH2)6CH2Br CH3(CH2)6CH2F 18-crown-6 (92%) benzene

  14. Polyether Antibiotics Monensin

  15. Polyether Antibiotics Monensin

  16. Polyether Antibiotics

More Related