The mechanism for the gold-catalyzed aerobic oxidation of alcohols was studied using a series of para-substituted benzyl alcohols (Hammett methodology). The competition experiments clearly show that the rate-determining step of the reaction involves the generation of a partial positive charge in the benzylic position (i.e. hydride abstraction). This was further substantiated by the determination of a significant kinetic isotope effect (k(H)/k(D) = 1.41), when employing an alcohol substrate deuterated in this position.
- heterogeneous catalysis