Planar Chromatographic Enantioseparations on Noncommercial CSPs
Numerous chiral stationary phases were used for the direct separation of optical isomers in planar chromatography. Only few stationary phases have been commercialized as precoated plates because of the high cost of most chiral adsorbents and the difficulty to detect analytes on stationary phases showing a strong adsorbance during exposition to ultraviolet (UV) lights. Cellulose tribenzoate (CTB) is an excellent stationary phase for chiral resolution of a large number of racemic alcohols and amides by column chromatography. Its use in planar chromatography was strongly limited because of high-UV adsorption background and the difficulty to find inexpensive materials. Several studies demonstrated that the chiral recognition mechanism of CTB was based on the formation of inclusion complexes and, simultaneously, of hydrogen bonds between alcoholic hydrogen of the analyte and the carbonyl group of the CTB.