Fe₃O₄@SiO₂ nanoparticles–functionalized Cu(II) Schiff base complex with an imidazolium moiety as an efficient and eco‐friendly bifunctional magnetically recoverable catalyst for the Strecker synthesis in aqueous media at room temperature

Abstract

Cu(II) Schiff base complex supported on Fe3O4@SiO2 nanoparticles was employed as a magnetic nanocatalyst (nanocomposite) with a phase transfer functionality for the one‐pot preparation of α‐aminonitriles (Strecker reaction). The desired α‐aminonitriles were obtained from the reaction of aromatic or aliphatic aldehydes, aniline or benzyl amine, NaCN, and 1.6 mol% of the catalyst in water at room temperature and good to excellent yields were obtained for all substrates. The catalyst was characterized analytically and instrumentally including Fourier‐transform infrared spectroscopy, X‐ray diffraction, thermogravimetric, nuclear magnetic resonance, energy‐dispersive X‐ray spectroscopy, inductively coupled plasma spectroscopy, vibrating‐sample magnetometry analysis, dynamic light scattering, Brunauer–Emmett–Teller surface area, field emission scanning electron microscopy, and transmission electron microscopy analyses. The reaction mechanism was investigated, in which the performance of the catalyst as a phase transition factor seems to be probable. The catalyst showed high activity, high turnover frequency (TOF)s, significant selectivity, and fast performance toward the Strecker synthesis. The nanocatalyst can be readily and quickly separated from the reaction mixture with an external magnet and can be reused for at least seven successive reaction cycles without significant reduction in efficiency.

An Fe3O4 supported O-phenylenediamine based tetraaza Schiff base-Cu(ii) complex as a novel nanomagnetic catalytic system for synthesis of pyrano[2,3-c]pyrazoles

“…In the first step, silica-modified Fe 3 O 4 MNPs were prepared using a previously established procedure. 32 Simultaneously, 2 g of Fe 3 O 4 @SiO 2 MNPs were dispersed in 100 mL of 95% ethanol, and a 20 mL solution of 0.25 M 3,4-diaminobenzoic acid in ethanol was added to the well-dispersed suspension and then refluxed for 12 hours under N 2 atmosphere. Afterward, the resulting Fe 3 O 4 @SiO 2 -diamine powder was magnetically collected, washed several times with ethanol and dried under vacuum.…”

Synthesis of a bistriazolyl-phenanthroline–Cu(ii) complex immobilized on nanomagnetic iron oxide as a novel green catalyst for synthesis of imidazoles via annulation reactions

“…In the first step, Fe 3 O 4 MNPs were prepared using a previously established procedure. 46 Simultaneously, 1 g of Fe 3 O 4 MNPs were dispersed in a mixture of ethanol and water (1 : 1) (100 mL) for 45 min, and a 3 mmol of l -azidohomoalanine hydrochloride was added to the reaction mixture and then refluxed under vigorous stirring and a N 2 atmosphere for 3 days. Afterward, the resulting Fe 3 O 4 @ l -AHA MNP product was magnetically collected, washed several times with ethanol and water and then dried under vacuum.…”