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ERIC Number: EJ1084322
Record Type: Journal
Publication Date: 2015-Dec
Pages: 7
Abstractor: As Provided
Reference Count: 27
ISBN: N/A
ISSN: ISSN-0021-9584
Heterogeneous Catalysis: Deuterium Exchange Reactions of Hydrogen and Methane
Mirich, Anne; Miller, Trisha Hoette; Klotz, Elsbeth; Mattson, Bruce
Journal of Chemical Education, v92 n12 p2087-2093 Dec 2015
Two gas phase deuterium/hydrogen exchange reactions are described utilizing a simple inexpensive glass catalyst tube containing 0.5% Pd on alumina through which gas mixtures can be passed and products collected for analysis. The first of these exchange reactions involves H[subscript 2] + D[subscript 2], which proceeds at temperatures as low as 77 K yielding a mixture that includes HD. Products are analyzed by [superscript 1]H NMR spectrometry. At low temperatures, this reaction requires a catalyst, but it proceeds without a catalyst at high temperature of a gentle flame. The second deuterium/hydrogen exchange reaction involves CH[subscript 4] + D[subscript 2] producing a series of isotopologues, methane-d[subscript x], x = 0-4, with product analysis by GC-MS and [superscript 1]H NMR spectrometry. This reaction only takes place in the presence of a catalyst at elevated temperatures due to the large energy of activation of the sp[superscript 3]-carbon-to-hydrogen bond. Two outcomes have been observed in the literature regarding D/H exchange and methane. Some catalysts and temperature conditions yield a single-exchange result, methane-d[subscript 1]. Others yield multiple exchange results, such as we observe with our catalyst. The single exchange outcome is associated with lower temperatures. Two mechanisms, one by Kemball (1959) and one by Frennet (1974), have been put forth to explain single and multiple exchange outcomes. We discuss our results in the context of these mechanisms. Interested readers could develop a research experience for undergraduate chemistry students based on the open-ended experiments presented here.
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
Publication Type: Journal Articles; Reports - Research
Education Level: Higher Education; Postsecondary Education
Audience: N/A
Language: English
Sponsor: N/A
Authoring Institution: N/A