Highly efficient FeNP-embedded hybrid bifunctional reduced graphene oxide for Knoevenagel condensation with active methylene compounds

Abstract

We have synthesized atypical highly active bifunctional FeNPs implanted on amino-modified reduced graphene oxide (FeNPs/Am@rGO) [where FeNPs = Fe nanoparticles; Am = Primary aromatic amine derivatives such as p-phenylenediamine (PPD) and/or aniline (AN)] as nanocatalysts via the acid–base dual-activation mechanism by introducing primary aromatic amines on the basal and/or edge sites of rGO that offer base characteristics and FeNPs anchored onto the surface of rGO that supply the Lewis acidic nature. These nanocatalysts were well corroborated through assorted physicochemical techniques. Impressively, FeNPs/Am@rGO significantly promoted a one-pot Knoevenagel condensation reaction with different aromatic aldehydes and active methylene compounds, thus bestowing excellent activity to give synthetically valuable multifunctional benzylidene derivatives. The impact of different parameters influencing the catalytic activity has also been monitored. Under the optimized conditions, FeNPs/PPD@rGO exclusively promoted the aforementioned reaction, leading to 100% benzaldehyde conversion with 100% yield of the product along with TON and TOF (h⁻¹) values of 350.8 and 100.2, respectively. Besides, it could be effortlessly recycled by centrifugation after each run and reused afterwards without significant loss in its catalytic activity in a six cycle test.