pH-Controlled Oxidation of an Aromatic Ketone: Structural Elucidation of the Products of Two Green Chemical Reactions

• C. Eric Ballard ^[1]
  1. [1] University of Tampa

     University of Tampa

     Estados Unidos

     
• Localización: Journal of chemical education, ISSN 0021-9584, Vol. 87, Nº 2 (February), 2010, págs. 190-193
• Idioma: inglés
• Texto completo no disponible (Saber más ...)
• Resumen

  • A laboratory experiment emphasizing the structural elucidation of organic compounds has been developed as a discovery exercise. The “unknown” compounds are the products of the pH-controlled oxidation of 4′-methoxyacetophenone with bleach. The chemoselectivity of this reaction is highly dependent on the pH of the reaction media: under basic conditions, the haloform reaction cleaves the methyl ketone yielding 4-methoxybenzoic acid, but under acidic conditions, electrophilic aromatic substitution of the aromatic ring occurs to generate 3′-chloro-4′-methoxyacetophenone. Each product was characterized by physical methods including melting point determination, IR and proton and carbon NMR spectroscopies, and mass spectrometry. Students analyzed the experimental data to determine the structures of the products. The experiment allows for an introduction of the concepts of chemoselectivity and regioselectivity and a discussion of redox reactions in organic chemistry. In addition, since the reactions were conducted using a relatively mild oxidant and with little organic solvent, principles of green chemistry and sustainable development are demonstrated.