Schiff Base-Functionalized Multi Walled Carbon Nano Tubes to Immobilization of Palladium Nanoparticles as Heterogeneous and Recyclable Nanocatalyst for Suzuki Reaction in Aqueous Media Under Mild Conditions

Abstract

Herein we described the synthesis of a novel Schiff base-MWCNTs-Pd nanocatalyst by covalent grafting of naphto-Schiff base onto carbon nanotubes and subsequent deposition of Pd nanoparticles. The synthetic process of preparation of mentioned nanocatalyst (Schiff base-MWCNTs-Pd) has been described. The formation of nanocatalyst was analyzed by FTIR, Raman spectroscopy, powder XRD, energy dispersive spectroscopy (EDS), thermogravimetric (TGA) analysis, wavelength-dispersive X-ray spectroscopy (WDX) and CHN analysis. The morphologies of the nanocatalyst were characterized using scanning and transmission electron microscopes (SEM and TEM). Additionally, the (Schiff base-MWCNTs-Pd) nanocatalyst was successfully employed in Suzuki cross coupling reactions with wide variety of functionalized substrates. Design of experiments indicates that the use of 0.2 mol% of Pd, K2CO3 as the base, and aqueous ethanol are the best reaction conditions. The reactions of aryl iodides and aryl bromides take place at room temperature, and aryl chlorides react at 80 °C. Interestingly, the novel catalyst could be recovered and recycled four times without any significant loss in activity.