Some Mechanistic and Analytical Studies of Tritium Labelling Procedures.

This thesis is concerned with the preparation of tritiated organic compounds by catalytic (both heterogeneous and homogeneous) methods. The radiochemical purity of the product(s) was usually ascertained by using a modified radio-gas-liquid chromatograph, ideally suited for compounds of high specific activity. The tritium distribution within the labelled compound was determined by 3H nmr spectroscopy. The starting point for the investigations was the establishment of a standard tritiation procedure which allowed the use of hydrogen-tritium mixtures, so that the most economic use of tritium gas could be made. In Chapter 1 the procedure is employed to hydrogenate a number of alkenes. A characteristic feature of the results is the uneven addition of tritium across the double bond. By deliberately under-reducing the substrate it can be shown that a competing exchange reaction is responsible for the above observation. In Chapter 2 the catalytic dehalogenation of a number of substrates is investigated whilst in Chapter 3 a detailed investigation is carried out into the hydrogenation of phenylacetylene. The preparation of N-succinimidyl [2,3-3H] propionate, a tritium labelling reagent for proteins is described in Chapter 4, as well as that of its inactive counterpart. The rates of hydrolysis and the optimum conditions for reaction with L-lysine and other substrates are also reported. In the final chapter details of the modifications made to a commercially available radio-gas-liquid chromatograph are given. Its sensitivity and general usefulness for the analysis of tritiated compounds is also discussed