Piperazine‐functionalized nickel ferrite nanoparticles as efficient and reusable catalysts for the solvent‐free synthesis of 2‐amino‐4H‐chromenes

Abstract

Piperazine‐functionalized nickel ferrite (NiFe2O4) nanoparticles were synthesized as recoverable heterogeneous base catalysts using a routine method. The synthesized materials were characterized using various spectroscopic techniques such as infrared, X‐ray diffraction, scanning electron microscopy, energy‐dispersive X‐ray, thermogravimetry analysis, and vibrating sample magnetometry. Catalytic efficiency was investigated in the synthesis of 2‐amino‐4H‐chromene derivatives via a one‐pot three component reaction of aldehyde and malononitrile with β or α‐naphthol/5‐methyle resorcinol under solvent‐free conditions with good to high yields. This method is operationally simple and has several advantages such as good to high yield, short reaction times, solvent‐free conditions, and easy synthesis. Moreover, the catalyst was recovered easily using an external magnet and reused three times without distinctive loss in catalytic activity.

Copper Schiff base complex immobilized on magnetic graphene oxide: Efficient heterogeneous nanocatalyst for treating environmental pollutants and synthesis of chromenes

“…To determine the leaching of copper species into solution, an ICP test was performed (after the sixth run). The amount of the Cu species of the nanocatalyst leached into the solution was found to be very low (0.11%), which confirmed the high stability of copper 2 NiFe 2 O 4 @propyl-Pip (0.04 g) Solvent-free 95 0.64 110 [53] 3 F e 3 O 4 @SiO 2 @VO (0.2 g) Solvent-free 98 1 110 [54] 4 F e 3 O 4 @salen of Cu(II) (0.05 g) Ethanol 83 1.32 60 [55] 5 Silica tungstic acid (0. complex on the support. Comparing the XRD patterns of the recycled nanocatalyst (after the sixth run) with the fresh one shows that the recycled nanocatalyst was rarely changed, and the XRD pattern of the reused nanocatalyst was preserved during the recycling (Figure 4d).…”

First Synthesis of 2-Amino-5-hydroxy-4H-chromene-3-carbonitriles from 4-(2-Pyridylazo)resorcinol

“…FIRST SYNTHESIS OF 2-AMINO-5-HYDROXY-4H-CHROMENE-3-CARBONITRILES It should be specially noted that, in the case of unsubstituted resorcinol [7][8][9][10][11][12] and 4-(arylazo)resorcinols [13][14][15][16], the condensation products are 7-OHchromenes, while in the case of PAR, 5-OH isomers 5 are formed. 5-Hydroxy-4Н-chromenes have been previously observed in the case of orcin (5-methylresorcinol) [40,41] or resorcinols having a strong acceptor substituent in position 4 [42][43][44]. In the 1 H NMR spectra of compounds 5, two characteristic [42][43][44]…”

Effective removal of Pb(II) ions using piperazine-modified magnetic graphene oxide nanocomposite; optimization by response surface methodology

“…Due to the various benefits of functionalization of nanomaterials, chemists have tried to covalently or noncovalently functionalize graphene oxide with various chemicals 36 and also biochemicals 37 , so that they are endowed with unique characteristics and excellent abilities 38 . In recent years piperazine functionalization has been performed for some applications including heavy metal ion removal 39 , loading of 2-mercaptobenzothiazole 40 , acid recovery by diffusion dialysis 41 and catalysis 42 .…”