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| Autor/in | Arulsamy, Navamoney |
|---|---|
| Titel | Ammonia Borane Acid-Base Complex: An Experiment Involving [superscript 1]H and [superscript 11]B NMR Spectroscopy and the Gas Laws |
| Quelle | In: Journal of Chemical Education, 95 (2018) 8, S.1381-1385 (5 Seiten)Infoseite zur Zeitschrift
PDF als Volltext |
| Sprache | englisch |
| Dokumenttyp | gedruckt; online; Zeitschriftenaufsatz |
| ISSN | 0021-9584 |
| DOI | 10.1021/acs.jchemed.8b00038 |
| Schlagwörter | Science Instruction; Science Experiments; Spectroscopy; College Science; Undergraduate Study; Inorganic Chemistry; Laboratory Experiments; Scientific Concepts; Concept Formation |
| Abstract | An experiment involving a moisture-sensitive synthesis and spectroscopic characterization suitable for the advanced inorganic laboratory course is presented. The acid-base complex ammonia borane (AB) is synthesized from the heterogeneous reaction between sodium borohydride and finely ground ammonium sulfate in tetrahydrofuran solvent. AB is isolated as a fluffy white solid. The [superscript 1]H and [superscript 11]B NMR spectra of AB, separately measured in the solvents D[subscript 2]O and CD[subscript 3]CN, provide an excellent opportunity to introduce some of the basic concepts of multinuclear NMR spectroscopy. The triplet and quartet peaks observed for the NH[subscript 3] and BH[subscript 3] groups in the [superscript 1]H spectrum measured in CD[subscript 3]CN can be used to discuss the nature of J[subscript NH] and J[subscript BH] coupling. The former coupling is rarely observed because the quadrupolar [superscript 14]N in nonspherical structures experiences rapid relaxation and large J coupling, leading to broad peaks for -NH and -NH[subscript 2] protons. Although such coupling due to [superscript 11]B is more commonly observed, a comparison of the [superscript 1]H NMR spectra of AB and NaBH[subscript 4] further illustrates the effect of spherical symmetry on the NMR behavior of quadrupolar nuclei. AB is also valued in the field of energy research as a potential chemical H[subscript 2] storage material and has assumed new significance as a potential portable energy source. The efficacy of H[subscript 2] generation from AB is examined, and the purity of student-synthesized samples is determined by applying the gas laws. The experiment can be performed in two 3-hour lab periods. (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 | 2020/1/01 |
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