Highly efficient and reusable Pd nanoparticles decorated on a novel Schiff base polymer for reduction of nitroarenes and Suzuki coupling reactions

Abstract

Environmental pollutants such as nitroarenes which released from several factories threaten flora, fauna and human life. Therefore, removal of these toxic substances from waste waters is of significance. Catalytic systems involving metal nanoparticles are effective to reduce hazardous nitroarenes and to fabricate biaryls, which are significant for pharmaceutical and natural product industries, via cross coupling reactions. The current research was conducted to produce a quick, highly efficient, simply recoverable and reusable nanocatalyst (Pd NPs@P(2-FAN)) involving Pd nanoparticles (Pd NPs) immobilized on a novel Schiff base polymer, Poly(2-((furan-2-ylmethylene)amino)-5-nitrophenol) (P(2-FAN)) for reduction of several toxic nitroarenes to harmless and useful organic molecules in water and fabrication of useful biaryls via Suzuki coupling (SC) reactions. UV–Vis, FTIR, TGA, XRD, FE-SEM and EDS techniques were used for characterizations of the synthesized materials. Then, catalytic performance of the produced Pd NPs@P(2-FAN) was examined in reduction of 2-nitroaniline, 4-nitroaniline, 4-nitrophenol, 4-nitro-o-phenylenediamine. Pd NPs@P(2-FAN) was reduced all these hazardous nitroarenes in water in very short time (between 30 and 85 s) with only 3 mg nanocatalyst using NaBH4. Moreover, Pd NPs@P(2-FAN) accomplished the fabrication of several biaryls via SC reactions using the microwave irradiation method in a solventless medium. This resulted in excellent reaction yields (99 %) with a very low catalyst amount (0.006 mol%) and a rapid reaction time (6 min). Additionally, performed reusability test results displayed that the nanocatalyst was simply recoverable and repeatedly reusable for successive six and eight cycles for reduction of nitroarenes and production of biaryls, respectively.