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15-Crown-5 is used as an efficient phase transfer catalyst and as a complexing agent. It is used to isolate oxonium ion (H7O3)+ salts especially from a solution of tetrchloroauric acid. It catalyzes the O-alkylation of the sodium salts of carboxylic acids in the penicillin and cephalosporin series, thereby facilitating esterification reaction without usage of acid. It is also used to facilitate the Williamson synthesis of ethers with hindered alcohols and sodium hydride. It is used with lithium aluminum hydride, for performing reduction reactions in hydrocarbon solvents. Further, it is involved in the Horner-Wadsworth-Emmons reaction to prepare stilbenes from aldehydes.
Crown ether (see Appendix 2) especially suited to complexing sodium ions. Thus, catalyzes the O-alkylation of the Na salts of carboxylic acids in the penicillin and cephalosporin series, providing a method for esterification without exposure to acid: Synthesis, 52, (1986).
Greatly facilitates the Williamson synthesis of ethers with hindered alcohols and NaH: Tetrahedron Lett., 38, 4679 (1997). Promotes the cleavage of unsymmetrical ethers by Sodium iodide, A15480, in the opposite sense to BBr3, i.e. by nucleophilic displacement from the less substituted carbon atom: Tetrahedron Lett., 22, 4239 (1981).
Greatly increases the reactivity of phosphonate anions generated by reaction with NaH in the Horner-Wadsworth-Emmons reaction. Thus, has been used in a high-yield synthesis of stilbenes from aldehydes and Diethyl benzylphosphonate, A10645: Synthesis, 117 (1981).
Use in combination with Lithium aluminum hydride, A18116, enables reductions to be carried out in hydrocarbon solvents: J. Chem. Soc., Chem. Commun., 1234 (1985).
Kuo, T. Y.; Tseng, W. H.; Chen, C. H. Force Spectroscopy of Metal-Crown Ether Multivalency: Effect of Local Environments on Energy Landscape and Sensing Kinetics. J. Phys. Chem. A 2015, 119 (29), 8097-8105.
Hazard Statements: H302-H313-H315-H319-H335
Harmful if swallowed. May be harmful in contact with skin. Causes skin irritation. Causes serious eye irritation. May cause respiratory irritation.
Precautionary Statements: P261-P280a-P305+P351+P338-P304+P340-P405-P501a
Avoid breathing dust/fume/gas/mist/vapours/spray. Wear protective gloves and eye/face protection. IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing. IF INHALED: Remove to fresh air and keep at rest in a position comfortable for breathing. Store locked up. Dispose of contents/container in accordance with local/regional/national/international regulations.