Synthesis and characterization of {Fe2CuO} clusters as precursors for nanosized catalytic system for Biginelli reaction

The novel μ₃-oxo-bridged heterotrinuclear iron(III)-copper(II) trichloroacetates of the composition [Fe₂CuO(CCl₃COO)₆(THF)₃] (1a) and [Fe₂CuO(CCl₃COO)₆(4-DMAP)₃] (1b) have been synthesized and characterized by X-ray crystallography, IR and Mossbauer spectroscopy. These clusters were used as precursors for the synthesis of the nanosized catalytic system (～5–6 nm of γ-Fe₂O₃/CuO), which works as an efficient organic phase catalyst (～0.02 mol%) in a one-pot three component Biginelli synthesis.     

Sunflower oil coating on the nanoparticles of iron(III) oxides

High-temperature solution phase reaction of iron(III)-furoate in sunflower oil, in the presence of trichloroacetic acid and 1,2-hexadecylamine leads to iron(III) oxide (amorphous and γ-Fe2O3) nanoparticles with sizes about 1.3 nm in diameter (method “A”), and about 5.5 nm (amorphous Fe2O3) from the “sunflower oil/oxadiazol” system (method “B”).     

Ultra dispersed particles of Fe(III) compounds in the strongly basic crosslinked ionic polymer-precursors for new sorbents and catalysts

The Mössbauer spectroscopy and SEM investigation shows that crosslinked ionic polymers containing strongly basic functional groups adsorb Fe(III)-containing cations from sulphate solution through the formation in the polymer phase of high dispersed particles of jarosite mineral type compounds. Using different procedures the particles sizes and morphology, their repartition on the surface and in the volume of the polymer granule, the composition of the “polymer-inorganic compound” structural units were modified that is important for sorbents and catalysts obtaining. On heating in water medium in a boiling water bath, a part of the jarosite type compounds in the polymer phase is converted into ultra fine β-FeOOH particles in superparamagnetic state and the rest, in relatively massive and magnetically ordered β-FeOOH particles. The higher is the content of the Fe(III) in the polymer phase, the shorter is the duration of heating in water for the appearance of relatively massive particles of β-FeOOH. The particles of the jarosite type compounds and of the β-FeOOH are formed both on the surface and in the volume of the polymer granule. Upon heating in water, a part of the Fe(III)-containing particles have migrated from the volume of the polymer granule to the surface. Thermogravimetric investigation (in an N₂ atmosphere) shows that on heating of the Fe(III)-containing polymer sample up to 900 °C, complicated processes take place.     

Effect of crystallization temperature on the synthesis of ETS-4 and ETS-10 titanosilicates

The effect of temperature on the crystallization and purity of (Na,K)-ETS-4 and (Na,K)-ETS-10 from gels with an optimized composition was examined. Microporous titano silicates (Na,K)-ETS-4 and (Na,K)-ETS-10 were obtained by hydrothermal synthesis from gels of molar composition 5x.Na₂O: 3KF: TiO₂: 6.4x.HCl: 7.45SiO₂: 197.5 H₂O where x = 2.0 for ETS-4 and x = 1.0 for ETS-10 in absence of seeds and organic template agents. The kinetics of crystallization at 160, 180 and 200 °C, respectively, by comparing gel crystallinity (%) at different times, the induction times and the apparent activation energies for nucleation and crystallization were studied. The induction time (linked to the formation of the first nuclei) suggests that the nucleation is more difficult in the case of ETS-10 and the crystal growth rates are similar at higher temperatures (>180 °C). The apparent activation energies are smaller for the (Na,K)-ETS-4 (a stable structure) crystallization than of (Na,K)-ETS-10 (a metastable structure). The characterization of these microporous materials was carried out by XRD, SEM and TGA-DSC techniques.