Exchange reactions between hydrogen and deuterium

Problem Determine the equilibrium constant of the homogeneous gaseous isotopic exchange reaction between hydrogen and deuterium iodide, via.,... 

Cinneide and Clarke (770) have studied the activity of Pd-Au films for the deuteration and exchange of benzene and the hydrogenation of p-xylene. The authors report that the activity for the exchange reaction between benzene and deuterium persists to the palladium-lean compositions, which is in agreement with results obtained by Honex et al. (Ill) in a study of the exchange of toluene over alloys of the same kind. The rates are much reduced (by 102 to 103) compared to those found with palladium-rich films. 

To cause the deuterium exchange reaction between hydrogen and ammonia to take place at a useful rate, it is necessary to have 1 to 2 m/o (mole percent) of potassium amide, KNH2, dissolved in the liquid phase to serve as a homogenous catalyst [C2]. Presence of potassium amide complicates the process for three reasons ... 

Section 7.4 described the development in Canada [S8] of a catalyst for the deuterium exchange reaction between hydrogen and liquid water that is not inactivated when submerged in water. 

Gupta NM, Mishra K, Belapurkar AD, et al Deuterium isotope exchange reaction between hydrogen and water over polyester-supported platinum catalysts, J Catal 121 (2) 386-395, 1990. 

Process 2, the adsorption of the reactant(s), is often quite rapid for nonporous adsorbents, but not necessarily so it appears to be the rate-limiting step for the water-gas reaction, CO + HjO = CO2 + H2, on Cu(lll) [200]. On the other hand, process 4, the desorption of products, must always be activated at least by Q, the heat of adsorption, and is much more apt to be slow. In fact, because of this expectation, certain seemingly paradoxical situations have arisen. For example, the catalyzed exchange between hydrogen and deuterium on metal surfaces may be quite rapid at temperatures well below room temperature and under circumstances such that the rate of desorption of the product HD appeared to be so slow that the observed reaction should not have been able to occur To be more specific, the originally proposed mechanism, due to Bonhoeffer and Farkas [201], was that of Eq. XVIII-32. That is. 

The hydrogen-deuterium exchange reaction between 140° and 491°K, H2 4- D2 == 2HD, which will be described in more detail in the next chapter, is caused in the higher temperature range by a predominating... 

A tracer technique was employed in an effort to gain further information about the reaction mechanism (10). One alpha hydrogen atom of n-octyl alcohol was replaced with an atom of deuterium. The steps of the two reaction mechanisms under discussion are presented in Fig. 2. If the exchange between hydrogen and deuterium is small, the presence of significant quantities of deuterium in the gaseous product may be explained only by mechanism (1). The exact experimental details of this investigation will now be discussed. 

Hydrogen spillover can be interestingly investigated with the help of isotopic molecules such as D2 and T2. Exchange reactions between the surface and the gas phase, and equilibration reactions involving hydrogen and deuterium, are easily monitored by IR spectroscopy, chromatography, and mass spectroscopy. 

The deuterium exchange reaction between water and hydrogen sulfide... 

Exchange reactions between hydrogen, deuterium, or tritium located at C-8 have been examined in a wide variety of purines and their derivatives which include the parent member, adenine," guanosine, hypo-xanthine, ° xanthine, 6-chloropurine, 6-mercaptopurine, - and others. 

Use of this vapor-phase deuterium exchange reaction between steam and hydrogen was proposed independently in 1941 by Harteck and co-workers in Germany and by Urey and co-workers in the United States as a means for recovering deuterium from electrolytic hydrogen. Harteck and Seuss [C3, G3] developed a supported nidcel catalyst that caused the... 

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... 

In this review paper we will be primarily concerned with the exchange between hydrogen and deuterium in aromatic compounds. Completely deuterated aromatics are available commercially. These are usually prepared by repeated treatment of the aromatic compound with DaO at about 350° in an autoclave in the presence of a platinum catalyst (Pt02 reduced with D2) h Such heterogeneous exchange reactions are not included in this review. 

The experiments of Rlttenberg and Urey (20) confirmed their calculations on this exchange reaction within the uncertainty of their calculations. Their calculation of the enharmonic correction to Eo, like many subsequent ones, is Incomplete. In the exchange reaction of protlum and deuterium between hydrogen gas and water vapor the deuterium favors the water molecule. 

For example, the catalytic reaction of isotope exchange between hydrogen and deuterium proceeds through three (I-III) reaction paths... 

Isotopic Exchange Reactions. Exchange reactions between the isotopes of hydrogen are well known and well substantiated. The equihbrium constants for exchange between the various hydrogen molecular species have been documented (18). Kinetics of the radiation-induced exchange reactions of hydrogen, deuterium, and tritium have been critically and authoritatively reviewed (31). The reaction T2 + H2 — 2HT equiUbrates at room temperature even without a catalyst (30). 

Hydrogen addition and exchange reactions between a bituminous coal and a donor solvent or a nondonor solvent were investigated using fully-deutrated Tetralin and naphthalene. In the experiments conducted with coal, Tetralin-di2 and deuterium at 400°C, the ratio of hydrogen exchange to addition was on the average 2.0. 

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