Microwave-Assisted Reductive Amination with Aqueous Ammonia: Sustainable Pathway Using Recyclable Magnetic Nickel-Based Nanocatalyst

The development of sustainable protocols for the reductive amination is a highly desirable pursuit in the domain of green synthesis. Magnetic nanocatalysts have found a unique niche in chemical synthesis in recent years as the recovery of expensive and/or toxic catalysts after their use are some of the salient features of these greener processes. Herein, we report the application of a recyclable nickel silica eggshell iron-based magnetic nanoparticles (Fe3O4@SiO2-Ni) for the expeditious microwave-assisted reductive amination of aryl aldehydes and ketones in aqueous ammonia; several desired primary amines were produced in good-to-excellent conversions. Extensive characterization of both, fresh and recycled Fe3O4@SiO2-Ni catalysts, showed that the Ni nanoparticles are highly dispersed on the silica shell and that the metal active phase is highly stable as the core–shell morphology is maintained after reaction, indeed the catalyst is recyclable up to six runs without deactivating. A synergic effect between t...