Synthesis of Jasminaldehyde by a Crossed Aldol Condensation: An Experiment for Undergraduate Organic Chemistry Students

TCE

The Chemical Educator

ISSN: 1430-4171 (electronic version)

Table of Contents

Abstract Volume 20 (2015) pp 321-326

Bioactive Compounds in the Olive Leaf: Introducing Hands-on HPLC-MS and NMR in the Undergraduate Curricula

Álvaro Raya Barón^†, David Arráez-Román^‡, Ignacio Fernández^†,§,*

†Department of Chemistry and Physics, Laboratory of Organic Chemistry, University of Almeria, Almeria, ES-04120, Spain, ifernan@ual.es; ‡Department of Analytical Chemistry, Faculty of Sciences, University of Granada, Granada, ES-18071, Spain; §BITAL, Research Center for Agricultural and Food Biotechnology, Almería ES-04120, Spain
Received August 13, 2015. Accepted September 28, 2015.

Published: 18 November 2015

Abstract. A laboratory exercise is described that involves the combined use of HPLC-MS (liquid chromatography–mass spectrometry), by means of TOF (time of flight) and IT (ion trap) as mass analyzers, and NMR (nuclear magnetic resonance) spectroscopy. The use of these techniques allows the full identification of the major phenolic compound in olive leaves and the correct assignment of its relative stereochemistry, i.e., (2S*, 4S*)-oleuropein. Through HPLC-MS, three isomers of oleuropein are detected, all of which have the same fragmentation pattern. By using NMR, the correct assignment of the ¹H NMR signals and the relative configuration of the stereocenters are precisely defined by means of TOCSY (total correlation spectroscopy) and NOESY (nuclear Overhauser spectroscopy) NMR experiments, respectively. This exercise gives students practice in olive leaf extraction processes, instrumental analysis, determination and interpretation of physical properties, and in the critical evaluation of results obtained using different analytical techniques. The take-home lesson is that important bioactive compounds are not only present in the olive oil but also in their leaves.

Key Words: Laboratories and Demonstrations; organic chemistry; NMR Spectroscopy; HPLC-MS; hands-on learning

(*) Corresponding author. (E-mail: ifernan@ual.es )

Article in PDF format (218 KB) HTML format

Supporting Materials:

Instructions for students and notes for instructors, base peak chromatogram, extracted ion chromatogram, mass and NMR spectra. (371 KB)