Evaluation of A Chiral Crown Etherlc Column For the Separation of Racemic Amines

Abstract

Enantiomeric resolution of more than fifty racemic primary amines can be achieved on a column that utilizes a crown ether as a chiral selector. The racemic solute is solubilized in an acidic solvent, forming an ammonium ion from the primary amine functional group. An interaction between the lone pair electrons on the oxygens of the crown ether and the positive charge of the ammonium group leads to the formation of an inclusion complex. Due to the chirality of the crown ether there is stereoselective interaction resulting in enantiomeric separation. Excellent resolution is possible for amino acids, amino alcohols, amino esters and amines. Compounds are separated that were poorly resolved by conventional ligand exchange columns and by other means.

Lanthanide-Crown Ether Mixtures as Chiral NMR Shift Reagents for Amino Acid Esters, Amines and Amino Alcohols

“…The selection of suitable chiral substrates for our study was based on previous liquid chromatographic data. 19 The crown ethers were e †ective NMR chiral resolving agents for protonated amino alcohols, protonated aromatic amines and methyl ester hydrochloride salts of amino acids. Enantiomeric resolution is not observed in the spectra of aliphatic amines such as 2-aminooctane and cyclohexylethylamine under the conditions employed.…”

Survey and Trends in the Preparation of Chemically Bonded Silica Phases for Liquid Chromatographic Analysis

“…Csato et al [122] prepared a pentafluorophenyl stationary phase and compared its chromatographic behavior to that of traditional phenyl columns. For separations of nucleosides and cyclic nucleotides, Kaliszan et al [126,127] prepared new HPLC stationary phases simultaneously containing the methylimidazole, pyridine, and cyano moieties.…”

Enantioselective capillary electrophoretic separation of tryptophane- and tyrosine-methylesters in a dual system with a tetra-oxadiaza-crown-ether derivative and a cyclodextrin

“…With the introduction of four carboxylic-acid groups they can be used as chiral selectors for the separation of enantiomers containing primary amine functional groups [15][16][17].…”