Gold catalysts are best known for their selectivity in oxidation reactions, however, there is a promising future for gold in selective hydrogenations. Herein, the hydrogenation of several aldehydes and important bio-based chemical building blocks, namely 5-hydroxymethylfurfural (5-HMF), furfural and vanillin, was performed throughout the combination of Au nanoparticles with Lewis bases. The Au-amine ligand (e.g., 2,4,6-trimethylpyridine) catalytic system could reduce the aldehyde carbonyl group selectively, without reducing alkene moieties or opening the furanic ring that occur on most traditional catalysts. Otherwise, the reduction of nitro group is preferential and the catalytic system was used for the synthesis of furfurylamines, important intermediates in the synthesis of different pharmaceuticals (e.g., furosemide), through the selective reductive amination of furfural starting from nitro-compounds. Moreover, a fully heterogeneous gold catalyst embedded in N-doped carbon (Au@N-doped carbon / TiO2) was able to perform these reactions in successive recycles without the addition of ligands, with impact in the development of a continuous flow process for biomass valorization.

Quantification of metal loading in supported catalysts is imperative; however, the analytical methods are usually time-consuming, expensive, and require sophisticated equipment and sample extraction with hazardous and corrosive strong acids. Herein, we report a new method for quantification of metal in supported catalysts using slurry sampling flame atomic absorption spectrometry. The slurry sampling method was used for determination of gold and the results were similar to those obtained with the traditional extraction method using aqua regia; however, it overcomes the main drawbacks associated with sample digestion by avoiding the use of concentrated toxic reagents, minimizing sample manipulation, and consequently, reducing the risks of contamination and the sample preparation time. Ultrasound radiation optimization associated with the solvent, mass of sample, concentration, and matrix effect in the slurry analysis allowed direct analysis by using the calibration in aqueous medium. The slurry sampling procedure could be applied to other catalysts with different supports and in bimetallic systems.

Neste trabalho descrevemos a obtenção de hidrocarbonetos líquidos por meio do hidrocraqueamento catalítico de óleo de soja, dendê e mamona, na presença e ausência de catalisadores nanoparticulados de rutênio e ródio. A reação realizada a 200 ºC leva somente à hidrogenação de ligações duplas C=C. No entanto, a 400 ºC, foi observada a decomposição dos triacilglicerídeos, levando a hidrocarbonetos e compostos oxigenados. O hidrocraqueamento catalítico de óleos vegetais na presença de Rh e Ru levou a um aumento da quantidade de produtos desoxigenados e à formação de hidrocarbonetos lineares de cadeia longa, que são adequados para utilização como combustível para motores diesel, quando comparado com o da reação de pirólise na ausência de catalisadores. O catalisador de Ru é mais eficaz do que o catalisador de Rh, especialmente no caso do óleo de mamona, provavelmente devido à sua maior oxofilicidade quando comparado com Rh.

We describe herein the production of liquid hydrocarbons through the catalytic hydrocracking of soybean, palm tree and castor oils, in the presence and absence of ruthenium and rhodium nanoparticle catalysts. The reaction at 200 ºC leads to the hydrogenation of C=C double bonds only. However, at 400 ºC, the decomposition of the triacylglycerides was observed, leading to hydrocarbons and oxygenated compounds. The catalyzed hydrocracking of vegetable oils in the presence of Rh and Ru strongly increased the amount of deoxygenated products and the formation of long-chain linear hydrocarbons, which are suitable for use as diesel fuel, when compared with pyrolysis reaction in the absence of the catalysts. The Ru catalyst is more effective than Rh, especially in the case of castor oil, probably due to its higher oxophilicity when compared to Rh.

A síntese e a caracterização de um novo filme polimérico composto por poli-{trans-[RuCl2(vpy)4 ]-estireno-4-vinilpiridina} impregnado com nanopartículas de prata são descritas neste trabalho. Este material foi obtido por polimerização em meio não aquoso envolvendo o complexo mononuclear trans-[RuCl2(vpy)4], o estireno (sty) e a 4-vinilpiridina (4-vpy), usando peróxido de benzoila como iniciador. As dimensões nanométricas das partículas de prata foram confirmadas através de microscopia eletrônica de transmissão (TEM) e por espectroscopia eletrônica no UV-visível. A morfologia do terpolímero foi caracterizada por microscopia eletrônica de varredura (MEV). As propriedades térmicas foram analisadas por termogravimetria (TGA) e calorimetria diferencial de varredura (DSC). A ação antimicrobiana do polímero impregnado com nanopartículas de prata foi avaliada utilizando microrganismos Gram positivo e Gram negativo, Staphylococcus aureus (ATCC 25923) e Escherichia coli (ATCC 25922), respectivamente. A atividade antimicrobiana do terpolímero com nanopartículas de prata foi confirmada pela presença de um halo de inibição do crescimento bacteriano nos meios de cultura semeados.

The synthesis and characterization of a new polymeric material composed of poly-{trans-[RuCl2(vpy)4 ]-styrene-4-vinylpyridine} impregnated with silver nanoparticles are here described. This material was obtained by a non aqueous polymerization reaction involving trans-[RuCl2(vpy)4], styrene (sty) and 4-vinylpyridine (4-vpy), using benzoyl peroxide as initiator. The silver particles nanometric dimensions were confirmed by transmission electron microscopy (TEM) and UV-visible spectroscopy. The terpolymer morphology was characterized by scanning electron microscopy (SEM). Thermal properties were analyzed by thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC). The antimicrobial action of the polymer impregnated with silver nanoparticles was evaluated by the use of Gram positive and Gram negative microorganisms, Staphylococcus aureus (ATCC 25923) and Escherichia coli (ATCC 25922), respectively. The antimicrobial activity of the terpolymer with silver nanoparticles was confirmed by the presence of a bacterial growth inhibition halo in seeded culture media.

A reação de NaBH4 com RuCl3 dissolvido no líquido iônico 1-n-butil-3-metilimidazólio hexafluorfosfato (BMI.PF6) é um método simples e reprodutível para a síntese de nanopartículas de RuO2 estáveis com distribuição estreita e diâmetro da partícula entre 2-3 nm. As nanopartículas de RuO2 foram caracterizadas por XRD, XPS, EDS e TEM. Estas nanopartículas mostraram alta atividade catalítica tanto na catálise heterogênea quanto na hidrogenação bifásica líquido-líquido de olefinas e arenos sob condições moderadas de reação. Experimentos de envenenamento com Hg(0) e CS2, e análises de XRD e TEM de partículas isoladas após a catálise indicaram a formação de nanopartículas de Ru(0). As nanopartículas podem ser reutilizadas em condições de catálise heterogênea até 10 vezes na hidrogenação de 1-hexeno rendendo um número total de ciclos catalíticos de 175.000 para átomos de Ru expostos.

The reaction of NaBH4 with RuCl3 dissolved in 1-n-butyl-3-methylimidazolium hexafluorophosphate (BMI.PF6) ionic liquid is a simple and reproducible method for the synthesis of stable RuO2 nanoparticles with a narrow size distribution within 2-3 nm. RuO2 nanoparticles were characterized by XRD, XPS, EDS and TEM. These nanoparticles showed high catalytic activity either in the solventless or liquid-liquid biphasic hydrogenation of olefins and arenes under mild reaction conditions. Hg(0) and CS2 poisoning experiments and XRD and TEM analysis of particles isolated after catalysis indicated the formation of Ru(0) nanoparticles. The nanoparticles could be re-used in solventless conditions up to 10 times in the hydrogenation of 1-hexene yielding a total turnover number for exposed Ru atoms of 175,000.

Neste trabalho, reportamos a síntese, caracterização e atividade de catecolase do complexo binuclear de cobre [Cu2(H2bbppnol)(mi-OAc)(mi-ClO 4)] ClO4·H2O·EtOAc contendo o ligante N,N'-2-hidroxibenzil-N,N' -2-piridilmetil-2-hidroxipropano-1,3-diamina (H3bbppnol). O complexo foi caracterizado através de espectroscopias no infravermelho e eletrônica, ressonância paramagnética eletrônica, medidas de susceptibilidade magnética e cristalografia de raios-X. A atividade de catecolase do complexo foi determinada espectrofotometricamente, monitorando-se a oxidação do substrato 3,5-di-terc-butilcatecol à correspondente o-benzoquinona, em solução de metanol saturada com O2/tampão aquoso (pH 8), a 25 ºC. O complexo mostrou-se capaz de oxidar o substrato modelo com uma constante catalítica de 0,0057 s-1.

The synthesis, characterization and catecholase activity studies of the complex [Cu2(H2bbppnol)(mu-OAc)(mu-ClO 4)]ClO4·H2O·EtOAc containing the dinucleating ligand N,N'-2-hydroxybenzyl-N,N' -2-pyridylmethyl-2-hydroxypropane-1,3-diamine (H3bbppnol) are presented here. The complex was characterized by IR, electronic and EPR spectroscopies, cyclic voltammetry, magnetic susceptibility measurements and X-ray crystallography. The catecholase-like activity of the complex was determined spectrophotometrically by monitoring the oxidation of 3,5-di-tert-butylcatechol to the corresponding o-benzoquinone in O2-saturated methanol/aqueous buffer (pH 8) mixtures at 25ºC. The complex was able to oxidize the model substrate with a turnover number of 0.0057 s-1.