Lithium tritide

Aromatic dehalogenation suffers from the disadvantage that only 50% of the tritium is incorporated, the rest appearing as waste. This situation is even more marked for borotritide reductions but the problem can be overcome by using some of the new tritide reagents that have recently become available as a result of the synthesis of carrier-free lithium tritide (Scheme 13.1) [22], Their reactivity can be fine-tuned through the elements (e. g. B, Al, Sn) to which the tritium is attached and by the electronic and steric nature of the substituents at the central atom. 

X (x = H or D). Such a result should be extrapolated to lithium-tritide solutions. In the same way Buxbaum (1982) have used yttrium for the separation of tritium from the liquid lithium breeder-blanket of a fusion reactor. 

Scheme 4.1 The range of tritide reagents available from highly reactive lithium tritide...

Total Pressure in the Chamber. The vapor species are Li, Li2, Pb, Pb , LiPb, He, hydrogen isotope molecules, and gaseous lithium hydride (including deuteride and tritide). The significant species are Li, Pb, He, and hydrogen isotope molecules. ... 

Lithium hydride is an industrial product utilized in organic synthesis, preparation of other hydrides, etc. The hydride, deuteride and tritide of Li play a role in the nuclear industry. 

Labeling with tritium in position 15 could easily be accomplished by reduction of retinaldehyde with sodium borotritide (Mayer and Isler, 1971) or of retinoic acid esters with lithium aluminum tritide, and, again, oxidation of the tritiated retinol (Kaegi et aL, 1982c) to retinaldehyde-15- H. Because of the favorable isotope effect, most of the isotope should stay attached to the aldehyde group. However, Futterman et aL (1979) found that all-frany-retinaldehyde-15- H is inadequate as a tracer for 11-c/y-retinaldehyde formation in a biological system. 

To adapt the reactions to the use of tritium, the following observations must be kept in mind. The preparation along these lines would be feasible for obtaining tritiated compounds of very low specific activity. Lithium aluminum tritide, being unstable, is available only at relatively low specific activities. Quenching a reaction with tritiated water, usually done in large excess, would be feasible only... 

Lithium boron tritide Glycitols-t from carbohydrates... 

The known 25-hydroxycholesterol acetate was brominated and the resulting 25-bromocholesterol was reduced with lithium aluminum tritide to give cholesterol-25- H (Joly et al., 1969). 

Tor the sake of convenience, tritide reagents designated by their formulas will always be written, as here, as if they contained only tritium. In reality, all reagents contain a mixture of tritium and hydrogen that varies with the specific activity of the reagent. For example, lithium borotritide of specific activity 80 Ci/mmol has the average formula approximately LiB H2.7Hi.3, and probably consists of a mixture of all possible isotopomers LiBH4, LiB HHj, LiB HoHz, LiB HoH and LiB H.. 

Preparation of Compounds Labeled with Tritium and Carbon-14 4.3.11 Lithium Aluminum Tritide (LiAl H4)... 

Figure 4.74 Applications of high specific activity lithium aluminum tritide ( )...

The reduction of lithium enolates of j8-keto esters with ZrCp2Cl H to give /8-tritiated a,j8-unsaturated esters has been demonstrated by the transmetallation of the lithium enolate of 301. followed by an intramolecular tritide transfer. Spontaneous elimination of O = ZrCp2 converted the intermediate zirconium enolate into 302. a key intermediate in the radiosynthesis of NVP GLC756 13031. The specific activity of 302 was 24Ci/mmoF ... 

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