Synthesis and Characterization of Zn_(1-x)Ni_xAl₂O₄Spinels as a New Heterogeneous Catalyst of Biginelli's Reaction

Abstract

Zn (1-x) Ni x Al 2 O 4 (x = 0.0-1.0) spinels were prepared at 800 °C by co-precipitation method and characterized by infrared spectroscopy, X-ray diffraction, scanning electron microscopy and X-ray photoelectron spectroscopy. The specific surface area was determined by BET. SEM image showed nano sized spherical particles. XPS confirmed the valence states of the metals, showing moderate Lewis character for the surface of materials. The powders were successfully used as new heterogeneous catalysts of Biginelli's reaction, a one-pot threecomponent reaction, leading to some dihydropyrimidinones (DHPMs). These new catalysts that produced good yields of DHPMs, were easily recovered by simple filtration and subsequently reused with persistent activity, and they are non-toxic and environmentally friendly. The optimum amount of catalyst is 20% by weight of benzaldehyde derivatives, while the doping amount has been found optimal for x = 0.1.

Hydrogen Production by Aqueous-Phase Reforming of Model Compounds of Wet Biomass over Platinum Catalysts

“…Furthermore, Figure e illustrates the O 1s spectrum. The peak located at 531.08 eV can be assigned to Al–O bonds …”

“…The peak located at 531.08 eV can be assigned to Al−O bonds. 33 For the Pt/Al 2 O 3 −CeO 2 catalyst, the atomic concentrations (%) of elements Pt, Al, Ce, O, and C were found to be 1.4, 45.1, 3.0, 44.0, and 6.4, respectively (as shown in Table 2). Figure 5a depicts the XPS wide spectra of the Pt/Al 2 O 3 −CeO 2 catalyst.…”

Synthesis and vasodilator activity of 3,4-dihydropyrimidin-2(1H)-ones bearing urea, thiourea, and sulfonylurea moieties

“…Key intermediates (4a-b) were prepared according to multicomponent Biginelli's reaction, by refluxing the appropriate nitrobenzaldehyde (1), the appropriate β-dicarbonyl compound (2) and urea (3) in acetonitrile in the presence of a catalytic amount of Zn 0.9 Ni 0.1 Al 2 O 4 . 20 The nitro group of 4a-b was catalytically reduced to give the amines 5a-b, using hydrogen and Pd/C (5%) under pressure (10 bars) at 65 °C, in anhydrous THF. The 3,4-dihydropyrimidin-2(1H)-one derivatives 6a-k and 7a-j were obtained by reacting an aryl isocyanate, an aryl isothiocyanate or an arylsulfonyl isocyanate with amines 5a-c in D r a f t anhydrous THF at room temperature.…”

“…In a 50 mL flask, the mixture of the appropriate aldehyde (5 mmol), ethyl acetoacetate (5 mmol), urea (7 mmol) and Zn 0.9 Ni 0.1 Al 2 O 4 (20% mass of the aldehyde) in ethanol (10 mL) was stirred under reflux for 4 hours. 20 The product was isolated after filtration of the catalyst on celite and evaporating the solvent. Recrystallization was performed with ethanol to yield pure dihydropyrimidinones 4a-c.…”

Effect of precursor synthesis on the physicochemical properties of Zn–Mg–Al mixed oxides

“…These compounds are synthesized by different methodologies. For Akika et al (2013) the co-precipitation method is the most attractive because it allows good stoichiometric control and reproducibility and produces pure materials with high surface area. Chang et al (2011), however, explain that mixed oxides obtained from hydrotalcite precursor synthesized by co-precipitation method have a small surface area.…”