Isolating Friedelin from Cork and Reducing It to Friedelinol and Epifriedelinol. A Project Involving NMR Spectrometry and Molecular Modeling

• Joseph W. LeFevre ^[1] ; Kristin I. McNeill ^[1] ; Janet L. Moore ^[1]
  1. [1] State University of New York

     State University of New York

     City of Albany, Estados Unidos

     
• Localización: Journal of chemical education, ISSN 0021-9584, Vol. 78, Nº 4, 2001, pág. 535
• Idioma: inglés
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• Resumen

  • In this four-week project, the pentacyclic triterpene friedelin is isolated from laboratory cork. The ground cork is refluxed in ethyl acetate, from which crude friedelin crystallizes. The crude product is analyzed by thin-layer chromatography and purified by flash chromatography. The resulting pure friedelin is reduced to friedelinol and epifriedelinol using different reduction conditions. Each product is analyzed by 1H NMR spectrometry and identified by comparing the CHOH signal with the corresponding signal in the model compounds, menthol and neomenthol. Finally, from computer-generated 3-D molecular models of each alcohol, key dihedral angles are measured and used to calculate three proton-proton coupling constants (J values) involving the CHOH proton. These values are compared to the actual J values determined by NMR spectrometry.