Synthesis and Hydrogenation of Disubstituted Chalcones. A Guided-Inquiry Organic Chemistry Project

• Autores: Jerry R. Mohrig, Christina Noring Hammond, Paul F. Schatz, Tammy A. Davidson
• Localización: Journal of chemical education, ISSN 0021-9584, Vol. 86, Nº. 2 (February), 2009, págs. 234-239
• Idioma: inglés
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• Resumen

  • Guided-inquiry experiments offer the same opportunities to participate in the process of science as classical organic qualitative analysis used to do. This three-week guided-inquiry project involves an aldol-dehydration synthesis of a chalcone chosen from a set of nine, followed by a catalytic transfer hydrogenation reaction using ammonium formate and Pd/C. The question each two-student team addresses is “Which of the functional groups of a multifunctional chalcone undergo hydrogenation in the reaction?” The regioselectivity is discovered by IR, NMR, and GC–MS spectrometric analysis. Students present their experimental results and conclusions to the entire lab section in a post-laboratory discussion held during the third week of the project, before their written results are due. The chalcone project was assessed at a large university in a laboratory class of 550 organic chemistry students using graduate-student teaching assistants. Student feedback was heavily favorable, both on the use of spectroscopy to determine the selectivity of hydrogenation and on the value of the post-lab discussion. The TA training and the faculty response are also discussed.