Isolation of (R)-(+)-Pulegone from the European Pennyroyal Mint, Mentha Pulegium

TCE

The Chemical Educator

ISSN: 1430-4171 (electronic version)

Table of Contents

Abstract Volume 7 Issue 5 (2002) pp 270-277

Isolation of (R)-(+)-Pulegone from the European Pennyroyal Mint, Mentha Pulegium

Larry G. French

Department of Chemistry, St. Lawrence University, Canton, NY 13617
Received June 3, 2002. Accepted August 21.2002

Published online: 20 September 2002

Abstract. Students obtain, via steam distillation, pennyroyal essential oil that is analyzed by capillary gas chromatography–mass spectrometry. TLC experiments establish conditions for preparative scale purification of the major oil component via flash column chromatography. The terpene obtained, (R)-(+)-pulegone, is characterized spectroscopically, employing at a minimum mass spectral molecular ion and fragmentation patterns, IR, and 300-MHz ¹H NMR. Optionally, ¹³C and 2-Dcorrelation NMR spectra can be utilized to enable unambiguous assignment of all C and H resonances. The project has been successfully incorporated into our upper-level advanced organic chemistry laboratory. The experiment provides opportunities for instruction in and experience with a wide variety of chromatographic and spectroscopic methods. Further, it centers on a plant and natural product well suited for the discussion of contemporary health care issues surrounding nontraditional/alternative medicine and herbal remedies.

Key Words: Laboratories and Demonstrations; organic chemistry; natural product isolation; pulegone; 2D-NMR; herbal medicine

(*) Corresponding author. (E-mail: lfrench@stlawu.edu)

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Supporting Materials:

Student Handout (Zip format 111 KB) 10.1007/s00897020599b