13 Isotopic Exchange Reactions of Difluoramine with Deuterium Oxide and Trifluoroacetic Acid
Downloaded by CORNELL UNIV on September 28, 2016 | http://pubs.acs.org Publication Date: January 1, 1966 | doi: 10.1021/ba-1966-0054.ch013
W A R R E N E. B E C K E R and F R E D J. IMPASTATO Ethyl Corp., Baton Rouge, L a . The isotopic exchange reactions of HNF with D O and with CF COOD have been investigated in tetrahydrofuran-d solution at low temperatures using NMR techniques. The former exchange is first order with respect to HNF and zero order with respect to D O. The latter exchange proceeds by this same path plus a second-order path. Both exchange reactions were studied at several temperatures, and the activation energies were determined. 2
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T y r h i l e investigating the mode of ionization of H N F , we had occasion W to study the isotopic exchange of hydrogen between H N F and D 0 . Although the literature contains two references (2, 9) to this ex change reaction, no attempt to determine the mechanism of exchange was made i n either of these investigations. W h e n we learned that the ex change is acid catalyzed, our study was extended to include the exchange of hydrogen between H N F and C F C O O D . Tetrahydrofuran-dg was used as solvent i n both of these studies. I n addition, the ionic behavior of H N F i n H S 0 was investigated by cryoscopic techniques. This pa per reports the results of these investigations. 2
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Experimental Reagents. Difluoramine was prepared from tetrafluorohydrazine ( A i r Products, Inc.) and thiophenol by the method of Freeman, Kennedy, and Colburn (3). It was purified by fractional condensation i n a high vacuum system and was stored i n a borosilicate glass bulb attached to the vacuum line. Deuterated trifluoroacetic acid was prepared by hydrolyzing a slight excess of trifluoroacetic anhydride with D Ô . The product was ρ urifled by distillation and stored under vacuum i n sealed glass ampoules until needed. The isotopic purity was estimated from N M R measurements to be at least 9 5 % . 2
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Holzmann; Advanced Propellant Chemistry Advances in Chemistry; American Chemical Society: Washington, DC, 1966.
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BECKER AND iMPASTATo
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Isotopic Exchange
Deuterium chloride was prepared by hydrolyzing acetyl chloride w i t h excess deuterium oxide. The product was purified by fractional condensa tion i n a high vacuum system and was stored i n a borosilicate glass bulb attached to the vacuum manifold. Tetrahydrofuran-d and D 0 , both of 9 8 % isotopic purity, were purchased from Merck, Sharp, and Dohme of Montreal. The tetrahydrofuran-
