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1997
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February
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In the Laboratory
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An Experiment to Demonstrate Magnetic Nonequivalence in Proton NMR
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Christopher J. Welch
Department of Pharmaceutical Chemistry, Organic Pharmaceutical Chemistry, Uppsala Biomedical Centre, Uppsala University, Box 574, S-751 23 Uppsala, Sweden
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February 1997
Vol. 74 No. 2
p. 247
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| Abstract |
The bicyclic compound, 3a,6a-diethoxycarbonyl-2,5-dimethyl-1,4-dioxo-octahydropyrrolo[3,4-c]pyrrole, prepared by a literature procedure is used to demonstrate magnetic nonequivalence for methylene protons in the proton NMR experiment. Two sets of nonequivalent protons are found, one for which constraints generated by inclusion in a ring cause large differences in magnetic environment giving rise to the nonequivalence, and a second where the magnetic environment experienced by two protons differs slightly during unrestricted rotation. In a first case the large difference in chemical shift gives an approximately first order coupling, whereas in the second case the chemical shifts differ only slightly giving overlap and the need for an algorithm for solution of the coupling constants.
See Letter re: this article.
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| More Information |
 Citation |
Welch, Christopher J. J. Chem. Educ. 1997 74 247.
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Keywords |
Spectroscopy, NMR Spectrometry, Organic Chemistry, Stereochemistry.
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History |
Created:
Last Updated: |
July 29, 1999
June 23, 2005
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Link to Letter added (May 2004).
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| Home > JCE Print > Journal of Chemical Education > Issues >
1997
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February
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247
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