Hydrogen/deuterium exchange reaction

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). 

J. W. Pyper and C. K. Briggs, Kinetics of the Radiation-induced Exchange Reactions of Hydrogen, Deuterium, and Tritium, Eawrence Eipermore Eaboratory Report... 

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. 

The most widely studied exchange reaction of a hydrogen atom bound to a carbon atom in a purine ring for deuterium or tritium involves the C8-H proton. Reactions with C6-HandC2-H are generally negligible. For the exchange reactions, deuterium oxide or tritium oxide is used, e.g. formation of 1 and I ... 

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

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. 

Table 13.18 Separation factors in liquid-vapor deuterium exchange reactions involving hydrogen...

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. 

The slightly different physical properties of deuterium allow its concentration in ordinary hydrogen (or the concentration of a deuterium-containing compound in a hydrogen compound) to be determined. Exchange of deuterium and hydrogen occurs and can be used to elucidate the mechanism of reactions (i.e. the deuterium is a non-radioactive tracer). Methanol exchanges with deuterium oxide thus ... 

Two types of hydrogen replacement are discussed here (1) the base-induced hydrogen-deuterium exchange reactions and (2) the hydrogen-metal exchange reactions. 

Miscellaneous Reactions. The A/-hydrogen atom of diphenylamine is reactive and readily replaced by deuterium by treating with C2H OD. The addition of acid cataly2es the exchange of the hydrogen atoms on the ring system (11). 

Pyridin-4-one, 1 -hydroxy-2,6-dimethyl-hydrogen-deuterium exchange reactions, 2, 196 Pyridin-4-one, 1-methyl-hydrogen-deuterium exchange, 2, 287 pK 2, 150 Pyridin-2-one imine tautomerism, 2, 158 Pyridin-2-one imine, 1-methyl-quaternization, 4, 503 Pyridin-4-one imine tautomerism, 2, 158 Pyridinone methides, 2, 331 tautomerism, 2, 158 Pyridinones acylation, 2, 352 alkylation, 2, 349 aromaticity, 2, 148 association... 

Tetrazole, 5-phenoxy-l -phenyl-mass spectra, 5, 801 photolysis, 5, 811 Tetrazole, 1-phenyl-deuterium-hydrogen exchange, 5, 806 mercuration, 5, 59 NMR, 5, 798 tautomerism, 5, 804 UV spectra, 5, 798 Tetrazole, 2-phenyl-NMR, 5, 798 tautomerism, 5, 804 UV spectra, 5, 798 Tetrazole, 5-phenyl-alkylation, 5, 818 anti-inflammatory activity, 5, 835 blowing agent, 1, 410 reactions... 

The earliest attempts to prepare deuterated steroids were carried out by exchange reactions of aliphatic hydrogens with deuterium in the presence of a surface catalyst. Cholesterol, for example, has been treated with platinum in a mixture of deuterium oxide and acetic acid-OD, and was found to yield... 

Reaction of acetone with D30+ yields hexadeuterioacetone. That is. all the hydrogens in acetone are exchanged for deuterium. Review the mechanism of mercuric ion-catalyzed alkyne hydration, and then propose a mechanism for this deuterium incorporation. 

Recently, other authors when studying the activation of hydrogen by nickel and nickel-copper catalysts in the hydrogen-deuterium exchange reaction concentrated for example only on the role of nickel in these alloys (56) or on a correlation between the true nickel concentration in the surface layer of an alloy, as stated by the Auger electron spectroscopy, and the catalytic activity (57). 

On the basis of these correlations, Gold and Satchell463 argued that the A-l mechanism must apply (see p. 4). However, a difficulty arises for the hydrogen exchange reaction because of the symmetrical reaction path which would mean that the slow step of the forward reaction [equilibrium (2) with E and X = H] would have to be a fast step [equivalent to equilibrium (1) with E and X = H] for the reverse reaction, and hence an impossible contradiction. Consequently, additional steps in the mechanism were proposed such that the initial fast equilibrium formed a 7t-complex, and that the hydrogen and deuterium atoms exchange positions in this jr-complex in two slow steps via the formation of a a-complex finally, in another fast equilibrium the deuterium atom is lost, viz. 

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