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Russian Journal of Applied Chemistry, Vol. 76, No. 3, 2003, p. 505. Translated from Zhurnal Prikladnoi Khimii, Vol. 76, No. 3,
2003, p. 520.
Original Russian Text Copyright + 2003 by Sakhabutdinov, Kulagina, Kushnarev, Proidakov, Kalabin.
Mechanism of Deuterium Distribution in Ethanols
A. G. Sakhabutdinov, N. V. Kulagina, D. F. Kushnarev,
A. G. Proidakov, and G. A. Kalabin
Institute of Petroleum and Coal Chemical Synthesis, Irkutsk State University, Irkutsk, Russia
Received October 10, 2002
Abstract-Deuterium distribution in ethanols produced by sulfuric acid hydration of ethylene was studied
by quantitative NMR spectroscopy.
It is well known that the natural content of deuteri-
um and the features of its distribution in structural
fragments of molecules bear information on the origin
of organic compounds . In synthetic ethanol the
deuterium content is 0.013430.0136%, and in food-
grade ethanol its level is lower, from 0.0114 to
0.0122% . However, irrespective of the ethanol
origin, the deuterium content in the methyl group is
higher than that in the methylene group by a factor of
1.131.4 in all cases . Since all deuterated molecules
occur in the form of d
isotopomer owing to minor
content of deuterium, it was of interest to establish
the mechanism of distribution of deuterium atoms
between methyl and methylene groups of alcohol.
For this purpose, we simulated formation of ethanol
by sulfuric acid hydration of ethylene and studied
the deuterium distribution in this process, using
deuterated sulfuric acid or [1,1-
It was found that, in the
H NMR spectrum of
ethanol produced by hydration of [1,1-
in the presence of sulfuric acid, the intensities of
signals of the methyl and methylene groups are the
same. This means that proton is added to both carbon
atoms of ethylene with equal probability, irrespective
of deuterium substitution. Thus, the deuterium atom in
the initial ethylene molecule does not affect the direc-
tion of proton addition and hence cannot be respons-
ible for the different natural deuterium content in
methyl and methylene groups of ethanol.
H NMR spectrum of ethanol produced by
hydration of ethylene in deuterated sulfuric acid
showed that addition of acid is accompanied by pre-
dominant deuteration of the methyl group, since the
intensity of its signal is greater by a factor of more
than 25 than the intensity of the signal of the methyl-
ene group. It is evident that, under the reaction condi-
tions, the reverse decomposition of ethyl hydrogen
sulfate to the initial substances proceeds to no more
than 8%, and hydrogen atom of the acid mainly par-
ticipates in formation of the methyl group.
The data obtained show that natural enrichment
of ethanol with deuterium is caused by two sorts of
deuterium atoms, deuterium of the substrate (ethylene)
and reagent (acid). The deuterium content in the initial
ethylene determines the amount of ethanol molecules
deuterated in the methylene group, while higher frac-
tion of molecules deuterated in the methyl group is
caused by deuterium from acid.
The reaction was carried out by the improved
procedure in . A mixture of 20 g of sulfuric acid
and 0.2 g of the catalyst Ag
stirred at 60oC in an ethylene medium until complete
saturation. The resulting ethyl hydrogen sulfate was
decomposed with a mixture of ice and water. The
yield of ethanol after twofold distillation was 60%.
Ethanol was analyzed by
H NMR spectroscopy on
a VXR-500S spectrometer operating at 76.7 MHz.
The pulse length was 25 ms (90o), and delay, 8 s.
The deuterium content in methyl and methylene
groups characterizes the components forming ethanol
and can be used for determining its origin.
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