Chiral Analysis of Linalool, an Important Natural Fragrance and Flavor Compound, by Molecular Rotational Resonance Spectroscopy

Abstract

The chiral analysis of terpenes in complex mixtures of essential oils, necessary for authentication, has been further developed using chiral tagging molecular rotational resonance (MRR) spectroscopy. One analyte that is of particular interest is linalool (3,7-dimethyl-1,6-octadien-3-ol), a common natural chiral terpene found in botanicals with its enantiomers having unique flavor, fragrance, and aromatherapy characteristics. In this MRR demonstration, resolution of the enantiomers is achieved through the addition of a chiral tag, which creates non-covalent diastereomeric complexes with distinct spectral signatures. The relative stereochemistry of the complexes is identified by the comparison of calculated spectroscopic parameters with experimentally determined parameters of the chiral complexes with high accuracy. The diastereomeric complex intensities are analyzed to determine the absolute configuration (AC) and enantiomeric excess (EE) in each sample. Here, we demonstrate the use of chiral tagging MRR spectroscopy to perform a quantitative routine enantiomer analysis of linalool in complex essential oil mixtures, without the need for reference samples or chromatographic separation.