Mechanism of Deuterium Distribution in Ethanols
Sakhabutdinov, A.; Kulagina, N.; Kushnarev, D.; Proidakov, A.; Kalabin, G.
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. BRIEF COMMUNICATIONS 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- ticipates in formation of the methyl group. um and the features of its distribution in structural The data obtained show that natural enrichment fragments of molecules bear information on the origin of ethanol with deuterium is caused by two sorts of of organic compounds . In synthetic ethanol the deuterium atoms, deuterium of the substrate (ethylene) deuterium content is 0.0134 0.0136%, and in food- and reagent (acid). The deuterium content in the initial grade ethanol its level is lower, from 0.0114 to ethylene determines the amount of ethanol molecules 0.0122% . However, irrespective of the ethanol deuterated in the methylene group, while higher frac- origin, the deuterium content in the methyl group is tion of molecules deuterated in the methyl group is higher than that in the methylene group by a factor of caused by deuterium from acid. 1.1 1.4 in all cases . Since all deuterated molecules occur in the form of d isotopomer owing to minor EXPERIMENTAL content of deuterium, it was of interest to establish the mechanism of distribution of deuterium atoms The reaction was carried out by the improved between methyl and methylene groups of alcohol. procedure in . A mixture of 20 g of sulfuric acid and 0.2 g of the catalyst Ag SO were vigorously For this purpose, we simulated formation of ethanol 2 4 stirred at 60 C in an ethylene medium until complete by sulfuric acid hydration of ethylene and studied saturation. The resulting ethyl hydrogen sulfate was the deuterium distribution in this process, using decomposed with a mixture of ice and water. The deuterated sulfuric acid or [1,1- H ]ethylene. yield of ethanol after twofold distillation was 60%. It was found that, in the H NMR spectrum of Ethanol was analyzed by H NMR spectroscopy on ethanol produced by hydration of [1,1- H ]ethylene a VXR-500S spectrometer operating at 76.7 MHz. in the presence of sulfuric acid, the intensities of The pulse length was 25 s (90 ), and delay, 8 s. signals of the methyl and methylene groups are the same. This means that proton is added to both carbon CONCLUSION atoms of ethylene with equal probability, irrespective of deuterium substitution. Thus, the deuterium atom in The deuterium content in methyl and methylene the initial ethylene molecule does not affect the direc- groups characterizes the components forming ethanol tion of proton addition and hence cannot be respons- and can be used for determining its origin. ible for the different natural deuterium content in methyl and methylene groups of ethanol. REFERENCES The H NMR spectrum of ethanol produced by hydration of ethylene in deuterated sulfuric acid 1. Martin, G.J., Martin, M.L., and Mabon, F., J. Am. showed that addition of acid is accompanied by pre- Chem. Soc., 1982, vol. 104, pp. 2658 2659. dominant deuteration of the methyl group, since the 2. Martin, G.J., Martin, M.L., Mabon, F., and Mi- intensity of its signal is greater by a factor of more chon, M.J., J. Agr. Food Chem., 1983, vol. 31, pp. 311 than 25 than the intensity of the signal of the methyl- 335. ene group. It is evident that, under the reaction condi- 3. Martin, G.J., Martin, M.L., Mabon, F., and Mi- chon, M.J., Anal. Chem., 1982, vol. 54, pp. 2380 2382. tions, the reverse decomposition of ethyl hydrogen sulfate to the initial substances proceeds to no more 4. Gluud, W. and Schneider, G., Chem. Ber., 1924, than 8%, and hydrogen atom of the acid mainly par- vol. 57, pp. 254 255. 1070-4272/03/7603-0505$25.00 2003 MAIK Nauka/Interperiodica
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