Abstract
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 H2 + D2, which proceeds at temperatures as low as 77 K yielding a mixture that includes HD. Products are analyzed by 1H 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 CH4 + D2 producing a series of isotopologues, methane-dx, x = 0-4, with product analysis by GC-MS and 1H 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 sp3-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-d1. 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.
| Original language | English |
|---|---|
| Pages (from-to) | 2087-2093 |
| Number of pages | 7 |
| Journal | Journal of Chemical Education |
| Volume | 92 |
| Issue number | 12 |
| DOIs | |
| State | Published - Sep 30 2015 |
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All Science Journal Classification (ASJC) codes
- Chemistry(all)
- Education
Cite this
Heterogeneous Catalysis : Deuterium Exchange Reactions of Hydrogen and Methane. / Mirich, Anne; Miller, Trisha Hoette; Klotz, Elsbeth; Mattson, Bruce M.
In: Journal of Chemical Education, Vol. 92, No. 12, 30.09.2015, p. 2087-2093.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Heterogeneous Catalysis
T2 - Deuterium Exchange Reactions of Hydrogen and Methane
AU - Mirich, Anne
AU - Miller, Trisha Hoette
AU - Klotz, Elsbeth
AU - Mattson, Bruce M.
PY - 2015/9/30
Y1 - 2015/9/30
N2 - 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 H2 + D2, which proceeds at temperatures as low as 77 K yielding a mixture that includes HD. Products are analyzed by 1H 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 CH4 + D2 producing a series of isotopologues, methane-dx, x = 0-4, with product analysis by GC-MS and 1H 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 sp3-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-d1. 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.
AB - 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 H2 + D2, which proceeds at temperatures as low as 77 K yielding a mixture that includes HD. Products are analyzed by 1H 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 CH4 + D2 producing a series of isotopologues, methane-dx, x = 0-4, with product analysis by GC-MS and 1H 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 sp3-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-d1. 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.
UR - http://www.scopus.com/inward/record.url?scp=84948957820&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84948957820&partnerID=8YFLogxK
U2 - 10.1021/acs.jchemed.5b00360
DO - 10.1021/acs.jchemed.5b00360
M3 - Article
AN - SCOPUS:84948957820
VL - 92
SP - 2087
EP - 2093
JO - Journal of Chemical Education
JF - Journal of Chemical Education
SN - 0021-9584
IS - 12
ER -