Tritium nuclear magnetic resonance studies of the specificity in plantinum-catalysed hydrogen isotope exchange of nitrogen heterocyclic compounds

The orientation of plantium-metal catalysed exchanged between tritiated water and pyridine, the picolines, 2,6-lutidine, and the quinolines has been carefully studied 3H n.m.r. Exchange at 130 °C occurs preferentially at a position adjacent to the nitrogen atom unless a methyl substituent on C-2 hinders exchange, when a position remote from the methyl substituent is preferred as in alkylaromatic exchange. The results are interpreted in terms of previously proposed π-complex exchange mechanisms.