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Exchange Reactions deuterium-water

Phutela, R. C. Kooner, Z. S. Fenby, D. V. Vapor pressure study of deuterium exchange reaction in water-ethanol system equilibrium constant determination. Aust. J. Chem. 1979, 32, 2353-2359. [Pg.74]

The deuterium exchange reaction between water and hydrogen sulfide... [Pg.1227]

Table 13.17 Separation factors in liquid-vapor deuterium exchange reactions involving water... [Pg.757]

The deuterium exchange reaction between water and ammonia, water and hydrogen sulfide, or water and the hydrogen halides proceeds rapidly in the liquid phase without catalysis, because of ionic dissociation. In the case of a mixture of water and hydrogen sulfide, for example, the ionic equilibria... [Pg.758]

Heavy water [11105-15-0] 1 2 produced by a combination of electrolysis and catalytic exchange reactions. Some nuclear reactors (qv) require heavy water as a moderator of neutrons. Plants for the production of heavy water were built by the U.S. government during World War II. These plants, located at Trad, British Columbia, Morgantown, West Virginia, and Savaimah River, South Carolina, have been shut down except for a portion of the Savaimah River plant, which produces heavy water by a three-stage process (see Deuterium and tritium) an H2S/H2O exchange process produces 15% D2O a vacuum distillation increases the concentration to 90% D2O an electrolysis system produces 99.75% D2O (58). [Pg.78]

To summarize, the use of heavy water as a deuterium source has provided a wealth of experimental information. Evidence for the associative ir-adsorption of benzene [species (I) J is secure (2). Evidence for hydrogen exchange in the benzene ring by an abstraction-addition mechanism is less well established, partly because of uncertainties that surround the mode of chemisorption and reaction of water at metal surfaces. Nevertheless, it would be wrong to deny that Scheme 6 is consistent with a large body of experimental work. [Pg.144]

Let us now turn to a comparison of theory with experiment. Comparing (95), (84), and (68), we find that the dependence of the photocatalytic effect K on the position of the Fermi level at the surface s and in the bulk cv of an unexcited sample for the oxidation of water is the same as for the oxidation of CO or for the hydrogen-deuterium exchange reaction. For this reason, such factors as the introduction of impurities into a specimen, the adsorption of gases on the surface of the specimen, and the preliminary treatment of the specimen will exert the same influence on the photocatalytic effect in all the three reactions indicated above. The dependence of K on the intensity I of the exciting light must also be the same in all the three cases. [Pg.201]

A feature common to both ir complex mechanisms is the nature of the second reagent in the exchange reaction [Eqs. (11), (12a), (12b)], namely heavy water or deuterium gas. Water is generally preferred in exchange reactions as it does not produce hydrogenated by-products. The important aspect concerning water and deuterium gas is the rapid exchange between these compounds on transition metal catalysts, which has been explained by dissociative chemisorption. [Pg.105]

To initiate an H/D exchange reaction, a protein sample, initially in non-deuterated buffer, is incubated in a buffer with 50-90% mole fraction deuterated water. There are almost no restrictions on reaction conditions which allow exchange behavior to be studied as a function of protein and buffer composition, solution pH, and in the presence and absence of ligands. To follow the deuterium buildup of individual amide hydrogen or sets of hydrogens, several on exchange time points are sampled for each condition. [Pg.380]

Deuterium may be analyzed from density measurements of waters. A confirmation method recommended here is GC mass spectrometry. Deuterium is burned in oxygen (or air) to form D2O which may be separated with helium on a GC column (of intermediate polarity) and identified from its mass spectra. The mass to charge ratio of the molecular ion is 20. Additionally, deuterated products obtained by exchange reactions with hydrogen containing substances (other than those containing C—H bonds) may be separated on a capillary GC column and identified by mass spectrometry. [Pg.288]

Analogous parahydrogen conversion and deuterium exchange reactions, catalyzed by NH2, have been observed in liquid ammonia (Wilmarth and Dayton, 61). The kinetics are of the same form as those of the OH -cat-alyzed reaction in water and the mechanism is open to similar interpretations. The NH2 -catalyzed reaction is much faster, its rate constant at —50° being 10 times that of the OH -catalyzed reaction at 100°. The assumption of equal frequency factors for the two reactions leads to a calculated activation energy for the NH2 -catalyzed reaction of about 10 kcal. This low value has been attributed to the much greater base strength of NH2 relative to OH . The results provide some support for the hydride ion mechanism. [Pg.323]

As a consequence, benzylic protons in a- and y-alkyl groups (but not in p-positions) are acidic and in water are in equilibrium with the corresponding methylenepyrans water at pH <5. Because the symmetric y-methylenepyrans (y-anhydrobases) are more stable than a-methylenepyrans [57], the isotopic exchange with deuterium oxide proceeds about ten times faster in y than in a, and this allows the synthesis of regiospecifically deuterated alkylpyrylium salts, which can then be converted into other deuterated compounds because the reaction with nucleophiles takes place even faster [58, 59],... [Pg.214]


See other pages where Exchange Reactions deuterium-water is mentioned: [Pg.754]    [Pg.756]    [Pg.195]    [Pg.282]    [Pg.266]    [Pg.6]    [Pg.7]    [Pg.163]    [Pg.112]    [Pg.12]    [Pg.134]    [Pg.143]    [Pg.143]    [Pg.415]    [Pg.178]    [Pg.135]    [Pg.72]    [Pg.106]    [Pg.113]    [Pg.114]    [Pg.288]    [Pg.49]    [Pg.29]    [Pg.357]    [Pg.360]    [Pg.360]    [Pg.361]    [Pg.166]    [Pg.166]    [Pg.266]    [Pg.353]    [Pg.119]    [Pg.445]    [Pg.122]    [Pg.46]    [Pg.197]    [Pg.444]   
See also in sourсe #XX -- [ Pg.181 , Pg.183 , Pg.193 ]




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