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In the Laboratory
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Study of an AB System within the 1H NMR Spectrum of a Maleamic Acid: Application of Chemical Exchange between Acid–Base Conjugates
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Pierre Fellmann
Institut de Biologie Physicochimique, UMR CNRS 7099, 75005 Paris, France
Alain Gevertz
UFR de Chimie, Service d'Enseignement et d'Instrumentation, Université Paris
7, BP 78251, Paris, France
Christine Cordier
ITODYS, UMR CNRS 7086, Université Paris 7, 75005 Paris, France
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March 2006
Vol. 83 No. 3
p. 432
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| Abstract |
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The 1H NMR spectrum of the system of two coupled protons shows two dissymmetric doublets; the frequency and intensity of the four lines are defined by calculations in the field of quantum chemistry. We propose an experimental verification of these results employing two vicinal olefinic protons. A mixture of N-(2-nitrophenyl) maleamic acid and its conjugated base in d6-DMSO, owing to fast chemical exchange, gives the spectrum of a mean entity characterized by a ratio (νA - νB)/J, which is function of molar fraction of the base form. Values of this ratio between 0 and 7.1 (at 200 MHz) are examined.
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| Supplement |
Notes for the instructor are available. Moreover, a set of spectra for the AB system where xb = 0, 0.25, 0.5; 0.75, and 1 is provided. For each spectrum, peaks are picked and integrated. Raw data (five FIDs) are also furnished.
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 Contents |
Folder JCE2006p0432W containing JCE2006p0432W.doc (Microsoft Word) and five additional folders.
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| More Information |
Citation |
Fellman, Pierre; Gevertz, Alain; Cordier, Christine. J. Chem. Educ. 2006 83 432.
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Keywords |
Acids / Bases; Alkenes; Fourier Transform Techniques; Graduate Education / Research; Hands-On Learning / Manipulatives; Laboratory Instruction; Molecular Mechanics / Dynamics; NMR Spectroscopy; Physical Chemistry; Quantum Chemistry; Spectroscopy; Upper-Division Undergraduate
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History |
Created:
Last Updated: |
1/31/2006
2/9/2006
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| Home > JCE Print > Journal of Chemical Education > Issues >
2006
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March
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432
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