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

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Joseph W. LeFevre , Kristin I. McNeill and Janet L. Moore

Chemistry Department, State University of New York (SUNY) at Oswego, Oswego, NY 13126

J. Chem. Educ., 2001, 78 (4), p 535

DOI: 10.1021/ed078p535

Publication Date (Web): April 1, 2001

Section:

History, Education, and Documentation

Abstract

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.

Keywords (Audience):

Upper-Division Undergraduate

Keywords (Domain):

Laboratory Instruction

Keywords (Pedagogy):

Hands-On Learning / Manipulatives

Keywords (Subject):

Chromatography

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This article has been cited by 1 ACS Journal articles (1 most recent appear below).

Assigning the NMR Spectrum of Glycidol: An Advanced Organic Chemistry Exercise
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- Assigning the NMR Spectrum of Glycidol: An Advanced Organic Chemistry Exercise
  Eric Helms , Nicholas Arpaia and Melissa Widener
  Journal of Chemical Education2007 84 (8), 1328
  This exercise combines conformational analysis and 1-D and 2-D NMR spectroscopy to correctly assign the proton and carbon NMR spectra of 2,3-epoxy-1-propanol (glycidol). In the process, students learn how to read DEPT-135, HETCOR, and COSY spectra. One ...
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