High-temperature solid-state catalytic isotope exchange

1 High-Temperature Solid-State Catalytic Isotope Exchange 

The most commonly used method of solvent-free exchange labeling, called high-temperature solid-state catalytic isotope exchange (HSCE), came into use in the late 1980s. It involves exposing a mixture of substrate, support and a metal catalyst to 

Sugars have also been tritiated for example, A-acetylneuraminic acid a-methylglyco-side (1651 to 12.5 Ci/mmol (2500 wt% of 5% Pd/C, 200 °C, 5 min) in 20-25% yield, and 

Much less studied is the use of zeolites as catalytic entities at elevated temperatures for sol vent-free exchange tritiation with tritium gas. Of the many types of zeolites, only metal-containing ones have been found to catalyze exchange from tritium gas. Published information in this area consists of pilot studies and the method has not been developed for routine practical use. The mechanism of labeling is evidently similar to that of HSCIE, in that tritium activated by the metal spills over via the zeolite to interact with substrate as an electrophilic entity. The most thorough study yet published includes results for labeling of alkyl-substituted aromatics, halobenzenes, saturated hydrocarbons and several simple heterocycles. 

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Table 3.1 Comparison of the effectiveness of thermal atom bombardment and high-temperature solid-state catalytic isotope exchange on selected substrates...

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