Ce-Doped α-FeOOH as a High-Performance Catalyst for Atom-Economic Synthesis of Imines: Enhanced Oxygen-Activating Capacity and Acidic Property

Iron oxide-hydroxide (FeOOH), a naturally abundant iron-based material, has been widely applied in electrode materials, adsorption of harmful ions, and degradation of organic pollutants. However, it has rarely been used as a heterogeneous catalyst in organic reactions. Herein, we attempt to extend its application to the catalytic synthesis of imines by preparing a Ce-doped α-FeOOH catalyst. The as-prepared Fe0.9Ce0.1OOH exhibited excellent catalytic performance in the atom-economic synthesis of imines by one-pot oxidative coupling from alcohols and amines. Mechanistic experiments and corresponding characterizations demonstrate that FeOOH acts as an intermediate facilitating the [O] cycling of Ce4+/Ce3+, enhancing the oxygen-activating capacity of the catalyst to accelerate the rate-controlling step of benzyl alcohol oxidation. Moreover, the FeOOH surface is rich in acid sites, which greatly promote the condensation of aldehyde and amine. The present work may provide new insights into the design of novel active and eco-friendly catalysts for organic oxidation reactions.