Nickel(ii) complex covalently anchored on core shell structured SiO2@Fe3O4 nanoparticles: a robust and magnetically retrievable catalyst for direct one-pot reductive amination of ketones

Abstract

A robust and efficient core shell structured magnetically retrievable nickel nanocatalytic system was fabricated via the covalent immobilization of 2-acetyl furan on the surface of an amine functionalized silica coated magnetic nanosupport followed by its metallation with nickel acetate. The newly synthesized magnetic silica based organic–inorganic hybrid nanocatalyst (Ni–ACF@Am–SiO₂@Fe₃O₄) was systematically affirmed using several physico-chemical characterization tools such as FT-IR, XRD, VSM, SEM, TEM, EDS, ED-XRF and AAS. Thereafter, the catalytic performance of this Ni–ACF@Am–SiO₂@Fe₃O₄ nanocatalyst was investigated in the one-pot reductive amination of ketones using NaBH₄ as the reductant under neat conditions. The developed core shell magnetic silica based nickel nanocatalyst successfully afforded a structurally diverse range of secondary amines with high turnover frequency (TOF) and excellent conversion percentage. Additionally, it was found that this catalyst could not only be retrieved from the reaction vessel within a fraction of seconds using an external magnet but also be recycled for multiple runs without any discernible loss in its activity that rendered this protocol superior to all the previously established methodologies for the one-pot synthesis of substituted amines. Besides, some of the other fascinating features of this methodology that made it a potential candidate for addressing various economic and environmental concerns were ambient reaction conditions, broad substrate scope, simple workup procedure, shorter reaction time and cost effectiveness.