Synergistic Effect of a Palladium‐on‐Carbon/Platinum‐on‐Carbon Mixed Catalyst in Hydrogen/Deuterium Exchange Reactions of Alkyl‐Substituted Aromatic Compounds

We have found a synergistic effect in the H‐D exchange reaction of alkyl‐substituted aromatic compounds using the Pd/C‐Pt/C‐D2O‐H2 system. This system would lead to fully H‐D exchange results even on the sterically hindered sites which were only low‐deuterium incorporated by Pd/C or Pt/C independently. Since the reaction was general for a variety of aromatic compounds, it could be applied to the deuteration of dianiline derivatives as raw materials for polyimides.