Chemistry of crown ethers (XVI). A safe and efficient procedure for the isolation and purification of crown ethers by complex formation with alkaline earth metal alkanedisulfonates

✍ Scribed by F. de Jong; D. N. Reinhoudt; A. van Zon; G. J. Torny; E. M. van de Vondervoort

• Publisher: Elsevier Science
• Year: 2010
• Tongue: English
• Weight: 418 KB
• Volume: 100
• Category: Article
• ISSN: 0165-0513
• DOI: 10.1002/recl.19811001204

✦ Synopsis

Abstract

A safe, efficient and selective method has been developed for the isolation and purification of crown ethers to replace the conventional procedure, which involves repeated vacuum distillations and has reportedly led to destructive explosions. The method is based on the formation of an insoluble 1:1 complex upon stirring a solution of a crown ether in an organic solvent with solid metal salts of 1,n‐alkanedisulfonic acids, such as barium and strontium methanedisulfonate and barium 1,2‐ethanedisulfonate. This extraction procedure can be applied to several crown ethers (including 18‐crown‐6) dissolved in a variety of solvents. Almost quantitative recovery of the crown ether is achieved by continuous extraction with nitromethane.

The usefulness of the method was illustrated by isolating 18‐crown‐6 from the crude mixture obtained in the course of its preparation. Whereas conventional workup (including two distillation steps) gave a 25% yield of pure 18‐crown‐6, the CH~2~(SO~3~)~2~Ba‐based method gave a yield of 34%.