A convenient synthetic method for preparing 12-crown-4, 15-crown-5, l&crown-6, and 21- crown-7 bearing various substituents by intramolecular cyclization of the corresponding substituted oligoethylene glycols in high yields is described. Substituents include modifiable pendent groups such as phenyl and hydroxymethyl, as well as various alkyl groups. Stability constants for the new substituted crown ethers with sodium and potassium ions in ...