Experimental Determination of pKa Values by Use of NMR Chemical Shifts, Revisited

• Alan D. Gift ^[1] ; Sarah M. Stewart ^[1] ; Patrick Kwete Bokashanga ^[1]
  1. [1] University of Nebraska at Omaha

     University of Nebraska at Omaha

     City of Omaha, Estados Unidos

     
• Localización: Journal of chemical education, ISSN 0021-9584, Vol. 89, Nº 11, 2012, págs. 1458-1460
• Idioma: inglés
• Texto completo no disponible (Saber más ...)
• Resumen

  • This laboratory experiment, using proton NMR spectroscopy to determine the dissociation constant for heterocyclic bases, has been modified from a previously described experiment. A solution of a substituted pyridine is prepared using deuterium oxide (D2O) as the solvent. The pH of the solution is adjusted and proton NMR spectra are collected for a variety of pH values. The chemical shifts of the peaks in the NMR spectrum change depending on the degree of protonation of the pyridine ring. Analysis of the spectral data is used to calculate the dissociation constant of the substituted pyridine. This experiment is suitable for a variety of advanced chemistry laboratories including analytical chemistry and instrumental analysis.