Síntese de catalisadores de nióbio suportados em óxidos mistos e suas aplicações em reações com aminas primárias

Abstract

A series of mixed metal oxides-supported niobium-based heterogeneous catalysts, prepared and characterized, was tested towards reactions with benzylamine and substituted benzylamines. The harmless and inexpensive hydrogen peroxide was employed as oxidizing agent aiming the formation of benzaldehyde oxime as main reaction product. The reactions were carried out under visible low spectrum violet light and led to good conversion rates from starting material but only modest selectivity was achieved based on gas chromatography–mass spectrometry data. When the reactions were performed at 50 °C in the presence of the niobium-based catalyst, it was possible to raise the selectivity for oxime as main product up to 70 %. The substrate scope using different substituted benzylamines was well tolerated and led to good isolated yields, suggesting the use of supported niobium-based catalysts, under mild oxidative conditions, as a reasonable method for the direct conversion of primary amines into their corresponding oximes.