Tritium exchange experiments

Mason and Smith (1969) found that for a series of mono- and bicyclic aromatic hydrocarbons the changes in the fluorescence spectrum with acidity reflected the ground state protonation reaction. The p Sj )-values calculated for benzene, toluene, naphthalene, azulene, and indolizine do not correspond to observable processes since the rate of protonation is too slow to compete with deactivation of the Sj state. Photochemical deuterium and tritium exchange experiments in 1 mole dm-3 perchloric acid indicate that the radiative deactivation rate of an electronically excited aromatic hydrocarbon is faster than the rate of protonation by a factor >10s. 

The tritiated version could be prepared from tritiated formic acid which we had prepared at high specific activity (2.5 Ci mmol-1) by a metal-catalyzed hydrogen-tritium exchange procedure using T2 gas. The material can be stored either as a solid or as a solution if the latter any release of tritium by back exchange can be easily monitored by 3H NMR spectroscopy. In our experience very little exchange occurs over several weeks of storage [51]. 

Hydrogen-Tritium Exchange Studies. Isotope exchange experiments were conducted as described previously for the 7-phase hydrides (except TiMo2, that does not form the 7-phase). The results of the isotope separation determinations are shown in Table VI, where the parameter a is defined as ... 

Laszlo Heredy We did make experiments with labeled anthracene, but the results were inconclusive as to whether any tritium exchange took place at any rate it is very small. It seems that the linear compound is simply less efficient both as solvent and reactant than an angular hydrocarbon like phenanthrene. 

Koretsky et al. calculated site densities for particular low index faces of six oxides and six silicate minerals and average site densities for cleavage and growth faces, and showed that these methods lead to very different results. Full documentation of depth, length of broken bond and Brown bond strengths of broken bonds for particular types of sites is presented. The ranges of TVs calculated by Koretsky et al. [7] and in their literature data collection (tritium exchange, acid-base titrations, NMR, adsorption and desorption of water at various conditions, and saturation experiments with different adsorbates in solution) for six oxides are listed in Table 5.1. 

The evidence from experiments involving deuterium and tritium exchange for hydrogen, as well as that from investigations of its catalysis,... 

The chiral samples of malonyl-CoA were then used to probe the steric course of fatty acid biosynthesis. Again, the experiment was complicated by tritium exchange during the incubation, both before and after the Claisen condensation step, resulting in 51% tritium retention from the S isomer and 23% tritium retention from the R isomer. Fatty acid biosynthesis involves Claisen condensation of malonyl-CoA with an acyl-CoA ester of 2 n carbon chain length to... 

Another series of experiments was done by Hong to test the tritium exchange or the hydrogen exchange of the various forms of the ferredoxin. 

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