On the Mixed Oxides-Supported Niobium Catalyst towards Benzylamine Oxidation

Abstract A series of mixed oxides-supported niobium-based catalysts has been synthesized and applied towards oxidation reactions of benzylamine derivatives. Under the optimized reaction conditions, the selectivity to oxime enhanced, leading to the main product with up to 72%. Moreover, even α-substituted benzylamines were well tolerated and led to oximes in good isolated yields. It is important to mention; four equivalents of the harmless and inexpensive hydrogen peroxide were employed as oxidizing agent. Mechanism hypothesis suggested that the reaction proceed to selective benzylamine oxidation into nitroso intermediate, following by formation of the corresponding oxime tautomer mediated by an unstable water produced by NbOx supported catalyst. This consists the first mixed oxides-supported niobium-based catalyst for selective oxidation of benzylamines to oximes.