Exchange radiation-induced

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... 

The production of tritium-labelled organic compounds was enormously facilitated by K. E. Wilz-bach s discovery in 1956 that tritium could be introduced merely by storing a compound under tritium gas for a few days or weeks the radiation induces exchange reactions between the hydrogen atoms in the compound and the tritium gas. The excess of gas is recovered for further use and the tritiated compound is purified chro-matographically. Another widely used method of... 

Reactions of atomic carbon, produced by nuclear reactions, with a number of hydrocarbons have been studied by Wolfgang and his collaborators (69). To minimize radiation induced secondary reactions which occur when use is made of C14, a technique has been developed using short-lived C11 produced by a neutron exchange reaction between a platinum foil and a C12 ion beam from a heavy ion accelerator. Part of the scattered Cu atoms has been allowed to penetrate through the thin brass foil wall of a brass vessel and come in contact with the compound wrhose reaction is studied. Products have been analyzed by gas chromatography using a technique of simultaneous mass and radioactivity determination. 

Figure 1. Radiation-induced hydrogen exchange in poly-a, L-glutamic add...

Catalysis of Hg/I Exchange on Silica - A Radiation-Induced Catalyic Entity... 

Parker, D.R. Radiation-induced exchanges in Drosophila females. Proc. Natl. Acad. Sci. U.S.A. 40 795-800, 1954. 

C. Radiation-Induced Exchange with Tritium Oxide. 182... 

By contrast with the radiation-induced procedures, isotope exchange reactions catalyzed by Group VIII transition metals are applicable to both deuterium and tritium labeling of heterocyclic compounds. Because of recent mechanistic developments in this field, it is possible to predict with some degree of certainty the reactivity of a molecule for deuteration and also for moderate levels of tritiation. If compensation for additional radiation-induced interactions is made, then the theory also satisfactorily explains high specific activity tritiations. 

It was also revealed by means of ultraviolet, visible and infrared optical absorption and hydrogen ion-exchange capacity measurements that the radiation induced defects such as fluorocarbon and peroxy radicals, and C=0 including in carbonyl groups were related to the new proton conduction processes. The modification of the hydrogen absorption characteristics due to the radiation induced defects in the near sttrface regions induces the enhancement of the proton conductivity. 

Radiation-induced exchange may be applied instead of thermal exchange, if thermal exchange does not occur below the decomposition temperature whereas the chemical bonds involved iii the exchange reaction are easily split under the influence of radiation. An example is the labelling of aromatic halogen compounds. 

An isolated Cr ion implanted in Mo(CO)g reacts either with the fragments formed during slowing down or with complete Mo(CO)g molecules through a radiation induced exchange reaction under formation of Cr(CO)g. The probability for this process is at RT about 50%. Fig. 28 shows how the formation probability develops under increasing dose conditions. 

Observations of identical kinetics for radiation-induced exchange and radiation-induced adsorption of D2 on silica gel have been said to support the identity of color and the catalytic site for H2-D2 exchange (91a), but the sites involved under the two ways of doing the experiments (preirradiation or simultaneous irradiation) are not necessarily the same (see Section V,c). 

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