Studies on the Mechanism of Transfer Hydrogenation of Nitroarenes by Formate Salts Catalyzed by Pd/C

The hydrogenation of nitroarenes to aminoarenes using formate salts as hydrogen donors and Pd/C as catalyst in a liquid/liquid/solid system was found to be a true hydrogen-transfer process. The mechanism of the reaction comprises successive adsorption of all three substrates to a single catalytic active site in the following order: nitroareane, formate anion, and water. Optimal concentrations of the substrates should be maintained to attain maximum reaction rate and overall yield. A general reaction mechanism is proposed.