Chiral thin-layer chromatography in dynamic studies: A short review

Abstract

Thin-layer chromatography (TLC) is a simple, cost-effective, and robust analytical technique, very useful in various different application fields like, e.g., fast screening and quality control of pharmaceuticals, phytochemicals, and alimentary products. Its versatility to a large extent owes to the seminal works of the late Professor Edward Soczewinski and, in the first instance, to the rationale implemented to liquid chromatography by the Soczewinski‒ Wachtmeister and the Snyder‒Soczewinski equations. Among the most challenging applications of TLC, one can name the enantioresolution of the racemic and scalemic mixtures and a statement that the chiral TLC in this particular respect outperforms the instrumentally more advanced chromatographic techniques is far from being an exaggeration. In the course of the past ca. 12 years, the authors of this paper have extensively investigated — mostly by means of chiral TLC — the enantioresolution of the low molecular weight carboxylic acids, to discover by sheer luck that all of them spontaneously undergo an oscillatory process, i.e., chiral conversion. Later, they collected abundant experimental evidence that the oscillatory chiral conversion is accompanied by the oscillatory condensation. Herewith, we highlight applications of the chiral TLC to demonstrate the dynamic phenomenon of the spontaneous oscillatory chiral conversion with the low molecular weight carboxylic acids.