Wilzbach methods, tritiation

For exchange of non-labile organic hydrogen atoms, acid-base catalysis (or some other catalytic hydrogen-transfer agent such as palladium or platinum) is required. The method routinely gives tritiated products having a specific activity almost 1000 times that obtained by the Wilzbach method shorter times are required (2-12h) and subsequent purification is easier. 

Exchange reactions may be carried out using tritiated solvent or tritiated gas, as in the Wilzbach method [19]. In the former procedure the sample is heated in a sealed tube with a hydrogen transfer catalyst and a tritiated solvent. In the Wilzbach procedure to which recourse is made only when... 

As a whole, these investigations provided valuable criteria to differentiate between the contributions ofthe various labeling mechanisms, and to determine their relative weight in the formation of the tritiated products. The currently accepted view (cf. Evans, 1966) is that the Wilzbach labeling method is essentially based on radiation-promoted processes, which largely predominate over the reactions of the HeT+ ions, as demonstrated by the fact that several T atoms are incorporated following each /8-decay. Under typical preparative conditions, the... 

Three types of radiation-induced procedures have been used including (a) recoil tritiation, (b) Wilzbach gas irradiation7 with its modifications, and (c) radiation synthesis.8 All these methods utilize high-energy ionizing radiation to achieve tritium incorporation. Wilzbach exchange7 is the most satisfactory of the three and has been the most widely used. Radiation synthesis is a relatively recent development of limited but valuable specificity. 

Radioactive compounds are obtained in various ways 1. by synthesis in the laboratory 2. biosyntheti-cally, using the specific synthetic capacities of organisms 3. by radiochemical methods, e.g. tritiated compounds by Wilzbach tritiation. The second and third technique often yield unspecific, uniform labeling, but not necessarily an equal degree or labeling of all atoms. For example, in Wilzbach labeling, the C-T bonds are stable, but the O-T and N-T bonds are labile. 

A method for preparing tritium-labelled oligosaccharides of hyaluronic acid has used the Wilzbach recoil technique the tritiated oligosaccharides are of potential use in studies of the mechanism of hyaluronidases. A four-fold helical form of hyaluronic acid has been detected using the data from fibre-... 

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