Isolation of (-)-Patchouli Alcohol from Patchouli Oil by Fractional Distillation and Crystallization

Purpose: To establish a new and efficient method for the isolation of (-)-patchouli alcohol (PA) from patchouli oil (PO). Methods: PO, obtained from commercial source, was separated into four fractions (A, B, C and raffinate) using fractional distillation according to pre-set reflux ratio in vacuum. PA was crystallized from fraction C (containing more than 80 % PA by weight) by cooling and centrifugation. Finally, PA was further purified by suction filtration. Characterization of PA was performed by melting point (MP), infrared spectroscopy (IR), 1H and 13C nuclear magnetic resonance spectroscopy (NMR) and mass spectrometry (MS). Results: The total yield of PA in this procedure reached 52.9 %. The structure of PA was obtained based on data from 1H-NMR, 13C-NMR and MS analysis with the aid of literature data for authenticated samples. Conclusion: Fractional distillation combined with crystallization can be successfully applied to the isolation of PA from PO in solvent-free conditions.