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A rapid analytical method for monitoring the enantiomeric purity of chiral molecules synthesized in ionic liquid solvents
Author(s) -
Zhao Qichao,
Twu Pamela,
Anderson Jared L.
Publication year - 2012
Publication title -
chirality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.43
H-Index - 77
eISSN - 1520-636X
pISSN - 0899-0042
DOI - 10.1002/chir.21983
Subject(s) - chemistry , derivatization , ionic liquid , enantiomer , chromatography , calibration curve , reagent , solid phase microextraction , sorbent , solvent , fiber , sample preparation , analytical chemistry (journal) , detection limit , organic chemistry , high performance liquid chromatography , mass spectrometry , gas chromatography–mass spectrometry , catalysis , adsorption
Ionic liquids (ILs) have been widely used as reaction solvents in asymmetric synthesis due to their interesting physical and chemical properties. However, monitoring reactant‐to‐product conversion and the enantiopurity of formed stereoisomers often involves a tedious extraction step before chromatographic analysis. In this study, a rapid and sensitive sampling method using headspace solid‐phase microextraction (SPME) coupled to chiral gas chromatography was developed for the “on‐line” analysis of chiral molecules in the IL solvent. Three different SPME sorbent coatings, namely polydimethylsiloxane, polyacrylate, and a polymeric ionic liquid‐based fiber, were examined in this study. The analytical performance of the developed method was evaluated in terms of reproducibility, slope of calibration curve, linear range, calibration linearity, and the determination of detection limits. The SPME method was successfully applied in the determination of enantiomeric excess from selected mixtures of chiral molecules. A preliminary study was performed using an “on‐fiber” derivatization approach revealing that the stereoisomers extracted by the SPME fiber can be efficiently derivatized using a short “on‐fiber” derivatization step. The developed SPME method eliminates the need of sequestering the reaction, separating the compounds of interest from the IL solvent, and the addition of a derivatizing reagent. Chirality, 2012. © 2012 Wiley Periodicals, Inc.