Selective oxidation of benzylamine to N‐benzyl benzaldimine over nanogold immobilized SBA‐15 under solvent‐free conditions

BACKGROUNDImines are important chemical intermediates for the fine chemical and pharmaceutical industry, particularly as lipoxygenase inhibitors, anti-inflammatory and anti-cancer agents. For the synthesis of imines, the standard protocol is the condensation of carbonyl compounds with amines in Lewis acids. Recently, considerable attention has been paid to oxidation of secondary amines. Subsequently, direct catalytic oxidation of primary amines has been emerging as a key methodology. However, limited studies have been made using Cu, Pd, Ru, Mn, Fe, V, Ti, Nb etc., as catalysts. Herein, nanogold immobilized Santa Barbara Amorphous (SBA-NG) catalyst has been described. RESULTSFor the synthesis of SBA-NG catalyst, SBA-15 was functionalized with propylamine (SBA-NH2) followed by immobilized nanogold particles using AuCl3 and NaBH4. Structural and textural characteristics of SBA-NG catalyst have been authenticated by low-angle XRD and N-2 sorption techniques. Metallic nature and 2-5nm sized nanogold have been assessed by wide-angle XRD and TEM analysis respectively. The SBA-NG converted benzylamine into N-benzyl benzaldimine with 98% conversion and 99% selectivity. CONCLUSIONSFacile preparation, high efficiency, stable activity, no solvent requirement, scope for large scale application are the credentials of SBA-NG catalyst, which are imparted by nanoscale dispersion, confined pore environment, high surface area and minimized diffusion limitations. (c) 2014 Society of Chemical Industry