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

Abstract

BACKGROUND: Imines 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. RESULTS: For the synthesis of SBA-NG catalyst, SBA-15 was functionalized with propylamine (SBA-NH 2 ) followed by immobilized nanogold particles using AuCl 3 and NaBH 4 . Structural and textural characteristics of SBA-NG catalyst have been authenticated by low-angle XRD and N 2 sorption techniques. Metallic nature and 2-5 nm 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. CONCLUSIONS: Facile 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.

Uniform Cu/chitosan beads as a green and reusable catalyst for facile synthesis of iminesviaoxidative coupling reaction

“…The oxidative coupling of primary amines is one of the promising alternatives to synthesize various imine products. 17 Homogeneous and heterogeneous catalysts based on V, 18 Mn, 19,20 Co, 21,22 Ru, 23 Pd, 24 Ir, 25 Au, [26][27][28] and Ce 29 have been proposed to catalyze this reaction. Over the past decades, researchers are very much interested in the copper-based catalysts for the oxidative coupling of primary amines.…”

Monomer Self‐Deposition for Ordered Mesoporous Carbon for High‐Performance Supercapacitors

“…The small-angle XRD patternso fO MC-1 (Figure 2c)e xhibit a clear diffraction peak at 2q = 0.988 corresponding to the (1 00) crystal plane,a nd aw ide peak at 2q = 1.958 ascribed to the (110)c rystal plane,w hich furtherc onfirmed the 2D hexagonal orderedm esoporouss tructure corresponding to the p6mm space group of SBA-15. [16] As depicted in Figure 2d,t he wideangle XRD patterns of OMC-1 show two wide peaks at 26 and 438,assigned to the signals of amorphous carbon.…”

Catalytic Transfer Hydrogenation of Furfural to Furfuryl Alcohol by using Ultrasmall Rh Nanoparticles Embedded on Diamine‐Functionalized KIT‐6

“…In the case of the ED‐KIT‐6 and Rh/ED‐KIT‐6 samples, a decrease in the intensity of the (2 2 0) and (4 2 0) planes was observed, again confirming the diamine‐functionalization and encapsulation of Rh nanoparticles. A similar set of observations was reported previously . The characteristic XRD peak of the metallic Rh (1 1 1) plane at 2 θ =41.3° was not observed owing to the high dispersion of ultrasmall Rh nanoparticles with a crystallite size below the XRD detection limit (<5 nm) with a low loading on the ED‐KIT‐6 matrix; these Rh nanoparticles were confirmed by TEM, energy‐dispersive X‐ray (EDX), and X‐ray photoelectron spectroscopy (XPS) analysis (Figure and Figure a).…”

“…KIT‐6 supported metal nanoparticles were synthesized in accordance with our previous report with slight modification . In a typical synthesis, the requisite amount of rhodium(III) acetylacetonate precursor corresponding to 1 wt % Rh was dissolved in dry dichloromethane, to which ED‐KIT‐6 (1 g) was added and stirred continuously at room temperature followed by solvent evaporation.…”