Investigating the Mechanism of Heteroaromatic Decarboxylation Using Solvent Kinetic Isotope Effects and Eyring Transition-State Theory

• Scott O. C. Mundle ^[1] ; Liliana Guevara Opiñska ^[1] ; Ronald Kluger ^[1] ; Andrew P. Dicks ^[1]
  1. [1] University of Toronto

     University of Toronto

     Canadá

     
• Localización: Journal of chemical education, ISSN 0021-9584, Vol. 88, Nº 7, 2011, págs. 1004-1006
• Idioma: inglés
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• Resumen

  • An upper-level mechanistic organic experiment is outlined where undergraduates measure kinetic rate constants for decarboxylation of pyrrole-2-carboxylic acid by the initial-rates method. UV spectroscopy is used to monitor reactant disappearance in both hydrochloric acid and deuterium chloride at different temperatures. Individual data are pooled and utilized by the class to calculate solvent kinetic isotope effects and reaction activation parameters (the latter from Eyring plots). Students interpret experimental results and additional literature data to deduce likely operative decarboxylation mechanisms at varying acidities.