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2007
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In the Laboratory
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Synthesis and NMR Spectral Analysis of Amine Heterocycles: The Effect of Asymmetry on the 1H and 13C NMR Spectra of N,O-Acetals
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Shahrokh Saba, James A. Ciaccio, Jennifer Espinal, and Courtney E. Aman
Department of Chemistry, Fordham University, Bronx, NY 10458
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June 2007
Vol. 84 No. 6
p. 1011
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| Abstract |
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We describe an undergraduate organic laboratory experiment in which students prepare two structurally similar heterocyclic amines from 2-(isopropylamino)ethanol, 1. One amine is achiral, 3-isopropyloxazolidine, 2, and the other chiral, (±)-3-isopropyl-2-(4-nitrophenyl)oxazolidine, 3. These N,O-acetals differ only by the presence of a single ring substituent that introduces asymmetry; thus, each compound has a distinct 1H and 13C NMR spectral pattern. Each student prepares 1, and then the class is divided into two groups: one group prepares 2, and the other group prepares 3. NMR spectroscopy clearly indicates that the nuclei of the methyl groups (and the hydrogens of each methylene) of 2 and 3 are enantiotopic and diastereotopic, respectively. Students must explain why the NMR spectra of 3 have more peaks in the aliphatic region and increased coupling in the 1H spectrum, leading to a discussion of prochirality and topicity of ligands within a single molecule. This operationally straightforward experiment is a meaningful exercise in chemical synthesis and spectral problem solving, and students sample the benefits of collaborative work by dividing up the synthetic and analytical tasks and then sharing their data.
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| Supplement |
Full procedures, instructions for students and NMR spectral data are available.
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| More Information |
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Citation |
Saba, Shahrokh; Ciaccio, James A.; Espinal, Jennifer; Aman, Courtney E. J. Chem. Educ. 2007, 84, 1011.
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Keywords |
Amines / Ammonium Compounds; Chirality / Optical Activity; Collaborative / Cooperative Learning; Green Chemistry; Hands-On Learning / Manipulatives; Heterocycles; Inquiry-Based / Discovery Learning; Laboratory Instruction; NMR Spectroscopy; Organic Chemistry; Second-Year Undergraduate; Stereochemistry; Synthesis
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History |
Created:
Last Updated: |
5/3/2007
5/3/2007
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 Caution! | | Experiments, laboratory exercises, lecture demonstrations, and other descriptions of the use of chemicals, apparatus, instruments, computers, and computer interfaces are presented in the Journal of Chemical Education as illustrative of new or improved ideas or concepts in chemistry instruction and are directed at qualified teachers. Although every effort is made to assure and encourage safe practices and safe use of chemicals, the Journal of Chemical Education cannot assume responsibility for uses made of its published materials. Many chemicals are hazardous. Precautions for the safe use of hazardous chemicals and directions for their proper disposal are described in the Material Safety Data Sheets and on the labels. We strongly urge all those planning to use materials from our pages to make choices and to develop procedures for laboratory and classroom safety in accordance with local needs and situations. |
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2007
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June
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1011
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