title: Supercritical Fluid Extraction, a Novel Method for Production of Enantiomers.
abstract: Extraction of 25 different binary mixtures of racemic acids [2-(4-isobutylphenyl)propionic acid, cis- and trans-chrysanthemic, and -permetric acid] and various chiral bases with supercritical carbon dioxide permitted the conclusion that molecular chiral differentiation in a supercritical fluid is more efficient than in conventional solvents. In the majority of cases, however, complete separation could not be achieved. In five cases, remarkable partial resolutions were realized (30-75% ee) and resolution was possible on a preparative scale. The pair cis-chrysanthemic acid and (S)-(+)-2-(benzylamino)-1-butanol was studied in detail. Pressure, temperature, time, as well as the molar ratio of base and acid had a marked influence on the quantity and quality of the products. Increasing pressure or decreasing temperature resulted in higher ee values. (-)-cis-Chrysanthemic acid in 99% ee was obtained from the raffinate in a single extraction step. Multiple extractions produced the (+)-cis-acid in 90% ee.
authors.affiliation: Technical University of Budapest, H-1521 Budapest, POB 91, Hungary.
authors.forename: Béla
authors.initials: B
authors.lastname: Simándi
authors.forename: Sándor
authors.initials: S
authors.lastname: Keszei
authors.forename: Elemér
authors.initials: E
authors.lastname: Fogassy
authors.forename: János
authors.initials: J
authors.lastname: Sawinsky