Combined deuterium nuclear magnetic resonance and mass-spectrometric studies of the exchange reactions of ketones over supported metal catalysts

Abstract

Deuterium NMR spectroscopy has been used in conjunction with mass spectrometry to study the exchange reaction of the ketones acetone, butan-2-one and cyclopentanone over a variety of supported metal catalysts. In many of the experiments simple, random, stepwise exchange was prevalent. However, in certain instances multiple exchange occurred. For butan-2-one and cyclopentanone this multiple exchange was essentially limited to the protons on carbon atoms adjacent to the carbonyl group, while for acetone a strong preference towards exchange into only a single methyl group was noted. Some hydrogenation to propan-2-ol accompanied the multiple exchange of acetone, with the majority of the alcohol being formed by addition of D₂ across the carbon oxygen double bond without simultaneous exchange into the methyl group, suggesting independent η₁ and η₂ adsorbed acetone surface intermediates for the exchange and hydrogenation reactions respectively.