Variable Temperature NMR Experiment Studying Restricted Bond Rotation

• Michael T. Huggins ^[1] ; Tanay Kesharwani ^[2] ; Jonathan Buttrick ^[2] ; Christopher Nicholson ^[3]
  1. [1] Tarleton State University

     Tarleton State University

     Estados Unidos

     
  2. [2] University of West Florida

     University of West Florida

     Estados Unidos

     
  3. [3] Marian University

     Marian University

     Township of Center, Estados Unidos

     

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• Localización: Journal of chemical education, ISSN 0021-9584, Vol. 97, Nº 5, 2020, págs. 1425-1429
• Idioma: inglés
• Texto completo no disponible (Saber más ...)
• Resumen

  • Nuclear magnetic resonance (NMR) spectroscopy has become a cornerstone tool for studying a variety of molecular features in advanced chemistry laboratories. In this experiment, students prepare a pyrrole-β-amide via a one-pot, three-step synthesis and use NMR spectroscopy to confirm its molecular structure. In addition, variable temperature (VT) 1H NMR spectroscopy is used to study the dynamic amide bond, a functional group with restricted rotation about the C–N bond. The VT NMR data allow the students to determine the coalescence temperature associated with the slow equilibrium at room temperature and the corresponding energy barrier (ΔG⧧) for the restricted rotation about the C–N bond.