Studies of the Interactions of Amino Alcohols Using High Performance Liquid Chromatography with Crown Ether Stationary Phases

Abstract

Separation of amino alcohols on two types of commercially available crown ethers stationary phases (Crownpak CR (+) and Chirosil RCA (+)) is presented. The difference between the two types of crown ether columns is that the Crownpak CR (+) column contains a large non-polar aromatic moiety, while the Chirosil RCA (+) consists of an immobilized crown ether tetracarboxylic acid. The interactions between the amino alcohols and the two stationary phases were characterized by their thermodynamic parameters. The influence of the organic modifier on the retention time and the enantioselectivity was studied using IR experiments. The IR spectra revealed that at a low concentration of organic modifier, Crownpak CR (+) self-interacts through its aromatic moieties, while Chirosil RCA (+) exists in both monomeric and dimeric state. At a higher concentration of organic modifier Crownpak CR (+) exits predominantly as a monomer, while Chirosil RCA (+) exists predominantly as a dimer.

Keywords:

• Chiral separation
• IR spectroscopy
• Van't Hoff plots