Literaturnachweis - Detailanzeige
| Autor/inn/en | Ieritano, Christian; Montgomery, Carlee A.; Goll, Julie M.; Chan, Ho Yin |
|---|---|
| Titel | Some Like It Hot: Experimentally Determining [delta][delta]"H"[thermodynamic], [delta][delta]"S"[thermodynamic], and [delta][delta]"G"[thermodynamic] between Kinetic and Thermodynamic Diels-Alder Pathways Using Microwave-Assisted Synthesis |
| Quelle | In: Journal of Chemical Education, 98 (2021) 2, S.577-586 (10 Seiten)Infoseite zur Zeitschrift
PDF als Volltext |
| Zusatzinformation | ORCID (Ieritano, Christian) ORCID (Goll, Julie M.) |
| Sprache | englisch |
| Dokumenttyp | gedruckt; online; Zeitschriftenaufsatz |
| ISSN | 0021-9584 |
| Schlagwörter | Science Instruction; Science Experiments; Thermodynamics; Kinetics; College Science; Undergraduate Study; Organic Chemistry; Hands on Science; Equipment |
| Abstract | The effects of kinetic vs thermodynamic control on "endo"/"exo" stereoisomer ratios can be observed in a simple Diels-Alder reaction between "N"-phenylmaleimide and furan. The use of microwave-promoted synthesis affords the cycloadducts in yields ranging from 65-100%, employing reaction times of 1-10 min at temperatures of 55-130 °C. Short reaction times enable screening of numerous reaction conditions (time and temperature) within a single lab period, where "endo":"exo" product ratios follow the primary facets of kinetic and thermodynamic control. Analysis of product ratios obtained under kinetic control allows for the evaluation of activation parameters ([delta][delta]"H"[thermodynamic] ([approximately equal to] [delta]"E"[subscript a]), [delta][delta]"S"[thermodynamic], and [delta][delta]"G"[thermodynamic]) by means of the Arrhenius and Eyring equations. Values of [delta][delta]"H"[thermodynamic], [delta][delta]"S"[thermodynamic], and [delta][delta]"G"[thermodynamic] were found to be 6.4 ± 0.3 kJ mol[superscript -1], 16.5 ± 0.9 J mol[superscript -1] K[superscript -1], and 1.5 ± 0.4 kJ mol[superscript -1] ([delta][delta]: "exo"-"endo"), respectively. Experimentally determined activation parameters correlate well with quantum-chemical calculations. Several key teaching points are also addressed, including frontier molecular orbital analysis, reversibility of the Diels-Alder reaction, column chromatography, and the use of [superscript 1]H nuclear magnetic resonance spectroscopy to assess both stereoisomeric yield and purity. (As Provided). |
| Anmerkungen | Division of Chemical Education, Inc. and ACS Publications Division of the American Chemical Society. 1155 Sixteenth Street NW, Washington, DC 20036. Tel: 800-227-5558; Tel: 202-872-4600; e-mail: eic@jce.acs.org; Web site: http://pubs.acs.org/jchemeduc |
| Erfasst von | ERIC (Education Resources Information Center), Washington, DC |
| Update | 2024/1/01 |
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