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- Ultrasound and radiation-induced catalytic oxidation of 1-phenylethanol to acetophenone with iron-containing particulate catalystsPublication . Soliman, Mohamed Mostafa Aboelhassan; Kopylovich, Maximilian N.; Alegria, Elisabete; Da Costa Ribeiro, Ana Paula; Ferraria, Ana Maria; Rego, Ana; Correia, Luís M. M.; Saraiva, Marta S.; Pombeiro, ArmandoIron-containingparticulatecatalystsof0.1–1 µmsizewerepreparedbywetandball-milling procedures from common salts and characterized by FTIR, TGA, UV-Vis, PXRD, FEG-SEM, and XPS analyses. It was found that when the wet method was used, semi-spherical magnetic nanoparticles were formed, whereas the mechanochemical method resulted in the formation of nonmagnetic microscale needles and rectangles. Catalytic activity of the prepared materials in the oxidation of 1-phenylethanol to acetophenone was assessed under conventional heating, microwave (MW) irradiation, ultrasound (US), and oscillating magnetic field of high frequency (induction heating). In general, the catalysts obtained by wet methods exhibit lower activities, whereas the materials prepared by ball milling afford better acetophenone yields (up to 83%). A significant increase in yield (up to 4 times) was observed under the induction heating if compared to conventional heating. The study demonstrated that MW, US irradiations, and induction heating may have great potential as alternative ways to activate the catalytic system for alcohol oxidation. The possibility of the synthesized material to be magnetically recoverable has been also verified.
- Mechanochemical preparation of Pd(II) and Pt(II) composites with carbonaceous materials and their application in the Suzuki-Miyaura reaction at several energy inputsPublication . Soliman, Mohamed Mostafa Aboelhassan; Peixoto, Andreia F.; Da Costa Ribeiro, Ana Paula; Kopylovich, Maximilian; Alegria, Elisabete; Pombeiro, ArmandoPd(II) and Pt(II) composites with activated carbon (AC), graphene oxide, and multiwalled carbon nanotubes were prepared by ball milling and used as catalysts for the Suzuki-Miyaura reaction, under several energy inputs (mechanical grinding, conventional heating, and microwave irradiation). The catalytic composites were characterized by ICP-MS, BET, XPS analyses, TEM, and SEM. The average particle size of the prepared composites was estimated to be in the range of 6-30 nm, while the loadings of Pd and Pt did not significantly affect the surface area of the AC support due to the tendency to agglomerate as observed by the TEM analysis. The Pd/AC composites exhibit high mechanochemical catalytic activity in cross-coupling of bromobenzene and phenylboronic acid with molar yields up to 80% with TON and TOF of 222 and 444 h(-1), respectively, achieved with Pd(4.7 wt%)-AC catalyst under the liquid assisted grinding for 0.5 h at ambient conditions, using cyclohexene as an additive.
- Vanadium C-scorpionate supported on mesoporous aptes-functionalized SBA-15 as catalyst for the peroxidative oxidation of benzyl alcoholPublication . Correia, Luís M. M.; Soliman, Mohamed Mostafa Aboelhassan; Granadeiro, Carlos; Balula, Salete; Martins, Luisa; Pombeiro, Armando; Alegria, ElisabeteThe neutral trichloro[hydrotris(1-pyrazolyl)methane]vanadium(III) [VCl3(Tpm)] (Tpm = HC(pz)(3); pz = pyrazolyl) C-scorpionate complex was immobilized on amine-functionalized mesoporous silica (aptesSBA-15) via an impregnation method forming the [VCl3(Tpm)]@aptesSBA-15 composite. The immobilization of the vanadium compound was confirmed by several characterization techniques, namely SEM/EDS, powder XRD, FT-IR/ATR, ICP and BET surface area analysis, revealing the successful incorporation of the complex, and confirming the structural and morphological preservation of the porous support and the vanadium complex. The vanadium composite was tested as heterogeneous catalyst for the peroxidative oxidation of benzyl alcohol under mild conditions and its catalytic performance was compared to that of the analogous homogeneous [VCl3(Tpm)] complex. The catalytic studies were extended to other substrates. The effect of various parameters, such as amount and type of oxidant, catalyst and additives, temperature and reaction time were investigated allowing to reach overall yields of ca. 60% and turnover numbers (TONs) up to ca. 7.6 x 10(3). The results obtained demonstrated the higher performance of the heterogeneous catalyst using much less [VCl3(Tpm)] complex under a solvent-free system. Furthermore, consecutive reaction cycles could be performed, showing its recycling capacity. Structural stability was also investigated, indicating the viability of the vanadium C-scorpionate composite as catalyst for other oxidative reactions with high industrial interest.
- A copper-amidocarboxylate based metal organic macrocycle and framework: synthesis, structure and catalytic activities towards microwave assisted alcohol oxidation and Knoevenagel reactionsPublication . Karmakar, Anirban; Soliman, Mohamed Mostafa Aboelhassan; Alegria, Elisabete; Rubio, Guilherme; Guedes Da Silva, M. Fátima C.; Pombeiro, ArmandoReactions of 3,3 '-{(pyridine-2,6-dicarbonyl)bis(azanediyl)}dibenzoic acid (H2L) with copper(ii) nitrate were studied and the obtained compounds [Cu-2(1:2 kappa(OO2)-O-1,2:3 kappa(OO4)-O-3-L)(mu-NO3)(mu(3)-OH)(MeOH)(2)](2)center dot 2MeOH center dot 1DMF (1) and [Cu(mu-1 kappa O-1:2 kappa O-2,3 kappa O-3:4 kappa O-4-L)(DMF)](n)center dot 4n(DMF) (2) were characterized by elemental analysis, FT-IR spectroscopy, and single-crystal and powder X-ray diffraction. Compound 1 is a macrocyclic tetranuclear Cu(ii) complex possessing a central, quasi-planar rhomboid shaped {Cu-4} cluster, which is the first example of a Cu(ii) based macrocyclic tetranuclear complex using such a linker. Compound 2 is a 2D metal organic framework having dinuclear paddlewheel type Cu(ii) assemblies that act as secondary building blocks. The topological analysis of framework 2 revealed that it has a 2,4-connected binodal net. Both compounds act as heterogeneous, easily recovered and reusable catalysts (the catalysts could be reused at least four times without significant loss of activity) for the microwave-assisted oxidation of several alcohols, as well as for the Knoevenagel condensation reaction of various aldehydes. The effect of reaction parameters such as temperature, time and type of oxidant was investigated. This study demonstrates that compound 1 can act as an efficient catalyst for the conversion of secondary alcohols (1-phenylethanol) to the corresponding ketones with high selectivity and yields up to 93% after 1 h of reaction at 120 degrees C and using t-BuOOH as an oxidant. Moreover, these compounds effectively catalyze the Knoevenagel condensation reactions of aldehydes with malononitrile and produce reaction yields between 64 and 99% within a very short period (10 min) under low power microwave irradiation. Furthermore, we have also studied the effectiveness of our catalyst 1 towards peroxidative oxidation/Knoevenagel condensation cascade reactions under microwave conditions.
- ZnO nanoparticles: An efficient catalyst for transesterification reaction of alpha-keto carboxylic estersPublication . Soliman, Mohamed Mostafa Aboelhassan; Karmakar, Anirban; Alegria, Elisabete; Da Costa Ribeiro, Ana Paula; Rubio, Guilherme; Saraiva, Marta S.; Guedes Da Silva, M. Fátima C.; Pombeiro, ArmandoPure ZnO nanoparticles were synthesized by a sustainable precipitation method using zinc nitrate and sodium hydroxide in aqueous medium at room temperature. They were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM-EDX), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy (UV-vis) spectroscopy and Brunauer-Emmett-Teller (BET) analysis. The XRD patterns indicate the formation of the hexagonal wurtzite phase with high purity and SEMEDS analysis confirm the purity and a homogenous distribution of the nanostructures. The ZnO nanostructures present plate-like agglomerates, resulting in a quasi-spherical morphology. The catalytic activity of the formed ZnO nanoparticles was evaluated towards the transesterification reaction of different carboxylic esters in the presence of various alcohols. This catalyst is highly selective for the transesterification of alpha-keto carboxylic ester (methyl benzoylformate) and leads to ca. 97% of product yield within 24 h of reaction time.
- Green synthesis of zinc oxide particles with apple-derived compounds and their application as catalysts in the transesterification of methyl benzoatesPublication . Soliman, Mohamed Mostafa Aboelhassan; Alegria, Elisabete; Da Costa Ribeiro, Ana Paula; Alves, Marta M; Saraiva, Marta S.; Montemor, M.F.; Pombeiro, ArmandoZnO nanoparticles (ZnONPs) were successfully synthesized using bravo-de-esmolfe apple extract in aqueous medium at room temperature. ZnO microparticles, prepared with a pure apple phytochemical, quercetin (ZnOq), or without phytochemicals (ZnO) were studied for comparative purposes. The re-use of apple waste for highly efficient catalyst production, based on green synthetic routes, can be added to the concept of a circular economy. The synthesized ZnO particles were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and N-2 adsorption/desorption Brunauer- Emmett-Teller (BET) theory. The XRD patterns indicated the formation of a hexagonal wurtzite phase with high purity and SEM and TEM analyses revealed the morphology of the particles. The apple extract produced spherical ZnONPs composed of round lamina-like structures, similar to the micro sized lamina-like shape of ZnOq and dissimilar to the flower-like shape of ZnO. The green synthesized ZnO nanoparticles (ZnONPs) led to a high product yield of ca. 96% within 24 h of reaction time in the transesterification reaction of different carboxylic esters.
- Highly active organosulfonic aryl-silica nanoparticles as efficient catalysts for biomass derived biodiesel and fuel additivesPublication . Peixoto, Andreia F.; Soliman, Mohamed Mostafa Aboelhassan; Pinto, Tânia V.; Silva, Sónia M.; Costa, Paula; Alegria, Elisabete; Freire, Cristina