T tritium

Isotopically Labeled Compounds. The hydrogen isotopes are given special names H (protium), H or D (deuterium), and H or T (tritium). The superscript designation is preferred because D and T disturb the alphabetical ordering in formulas. 

Transition state theory has been useful in providing a rationale for the so-called kinetic isotope effect. The kinetic isotope effect is used by enzy-mologists to probe various aspects of mechanism. Importantly, measured kinetic isotope effects have also been used to monitor if non-classical behaviour is a feature of enzyme-catalysed hydrogen transfer reactions. The kinetic isotope effect arises because of the differential reactivity of, for example, a C-H (protium), a C-D (deuterium) and a C-T (tritium) bond. 

As seen in Fig. 3.23, the absorption-desorption curves for H are different from those for D. This phenomena is used in types (3) and (4). By use of this phenomena, the separation of H and D, and enrichment of H and D from mixed gas are possible. The absorption-desorption curve for T (tritium) also differs from those for H and D thus we can separate and enrich H or D or T from the mixed gases by use of the absorption-desorption curves. D and T, which are used in nuclear reactors and nuclear fusion reactors, can be very efficiently separated and enriched by this principle. 

D—deuterium, heavy stable hydrogen, 1 proton + 1 neutron T—tritium, radioactive hydrogen, 1 proton + 2 neutrons... 

Tritium is the heavy isotope of hydrogen (section 5.2). Its symbol is 3H, or T. Tritium atoms are unstable and disintegrate radioactively, forming stable 3He atoms. The radioactive decay is accompanied by the emission of [1 particles, measurable in specific laboratories ... 

SUPO Super Power Water Boiler T tritium... 

The easiest labels to use for this job are D for H, and 0. None of these is radioactive all can be found by mass spectrometry, while D and can be found by NMR. Old work on mechanisms used radioactive tracers such as T (tritium) for H and fhesc are isotopes of hydrogen and carbon... 

When UMP is dissolved in T2O (T = tritium see Problem 27), exchange of T for H occurs at the 5-position. Propose a mechanism for this exchange. 

Figure 8.47 Stereochemistry in Catalysis. Biocatalyst stereochemistry may be followed with chiral substrates to reveal stereochemical changes during catalysis. Substrates include, chiral acetylCoA and phosphate (that undergo inversion or retention of configuration with reaction), and chiral NADH(D) designed to demonstrate whether prochiral (proR or proS) are employed in reduction. mMDH uses the proR hydrogen as illustrated by deuterium (D) transfer to the product (bottom). D, deuterium T, tritium.

Starting with 2-methylpropene (isobutylene) and using any other needed reagents, outline a synthesis of each of the following (T = tritium, D = deuterium) ... 

The strong coupling shown above takes place because the individual vibrators are identical. The less similar they are in terms of frequency, the lower will be the degree of coupling. This is revealed by consideration of the frequencies of simple triatomic linear cyanide molecules shown in Table 2. For HCN and the halogenides, the natural (isolated) C-H or C-halogen frequencies are very different from v(C=N) and there is little interaction, as demonstrated by the roughly constant values of the latter. But this is not so for DCN and TCN (T = tritium), where by extrapolation from v(C-H) the C-D and C-T oscillators would have natural frequencies of about 2430 and 2050 cm" respectively. 

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