Persona: Martín Aranda, Rosa María
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Martín Aranda
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Rosa María
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Publicación Tantalum vs Niobium MCF nanocatalysts in the green synthesis of chromene derivatives(Elsevier, 2019-03-15) Smuszkiewicz, Agata; López Sanz, Jesús; Sobczakb, Izabela; Ziolek, María; Martín Aranda, Rosa María; Pérez Mayoral, María ElenaTaMCF silicas modified with alkaline metals can be considered a novel family of highly efficient bifunctional catalysts involved in the synthesis of chromene derivatives, from salicylaldehyde 2 and acetonitrile compounds, under mild conditions, showing enhanced catalytic performance than their NbMCF analogues. The observed reactivity was mainly attributed to the higher basicity of the Me/TaMCF but also the texture of the samples. The Me/TaMCF silicas showed higher Brønsted basicity than the Nb ones as indicated by the stronger interaction between alkali metals and Ta in the UV–vis and the test reaction experiments. On the other hand, the basicity of Me/TaMCF together the reactivity degree and steric hindrance of the starting acetonitriles are key factors influencing the reaction selectivity. In conclusion, the basicity of the samples plays an important role initiating the reaction by activation of nucleophile but also a compromise between alkaline cation size and basicity is required.Publicación The role of gold dopant in AP-Nb/MCF and AP-MCF on the Knoevenagel condensation of ethyl cyanoacetate with benzaldehyde and 2,4- dichlorobenzaldehyde(Elsevier, 2019-03-15) Sobczaka, Izabela; Wolskia, Lukasz; Siodlaa, Tomasz; Ziolek, María; Calvino Casilda, Vanesa; Martín Aranda, Rosa MaríaThe Knoevenagel condensation with chlorine substituted benzaldehyde is difficult because of deactivation of aldehyde group. In this work we have shown that the activity of mesoporous cellular foams (MCF and Nb/MCF), modified with 3-aminopropyl-trimethoxysilane (AP) as a source of basicity, can be enhanced for this reaction by the anchoring of gold species. Gold species were loaded on amine modified materials towards Au/AP-MCF and Au/AP-Nb/MCF. Moreover, copper was used as a dopant for the latter sample giving rise to AuCu/AP/MCF. All these materials were characterized in details by different complementary techniques (N2 adsorption isotherms, TEM, UV–vis, TG/DTA, XPS, DFT calculations) which allowed the evaluation of states of all components of the catalysts. The interaction between niobium species and AP was evidenced to increase the stability of the basic modifier. This interaction was weakened by the introduction of gold and copper. The presence of both, negatively charged gold nanoparticles (NPs) and gold cations was crucial for the activation of 2,4-dichlorobenzaldehyde via the interaction with chlorine substituent atoms and aldehyde oxygen atoms as well as breaking of the “pseudo hydrogen bond” between aldehyde hydrogen atom and chlorine substituent, which destabilized the structure making it more active. Gold dopants did not influence significantly the condensation of ethyl cyanoacetate with benzaldehyde.Publicación Impact of Brønsted acid sites in MWW zeolites modified with cesium and amine species on Knoevenagel condensation(Elsevier, 2019-05-15) Wojtaszek Gurdak, Anna; Grzesinska, Aneta; Ziolek, María; Calvino Casilda, Vanesa; Martín Aranda, Rosa MaríaLayered zeolites of MWW family, MCM-22 and pillared MCM-36, were used as supports for base modifiers: cesium species (introduced via cation exchange or impregnation) and 3-aminopropyl trimethoxysilane (AP). The obtained materials were characterized by different methods (ICP-OES, N2 adsorption, XRD, XPS, TG/DTA, FTIR combined with pyridine adsorption, 2-propanol decomposition) for evaluation of chemical, structural and surface properties. All materials obtained were subjected to the Knoevenagel condensation of benzaldehyde with ethyl cyanoacetate and ethyl acetoacetate. The effect of the zeolite structure, the stability of the catalysts as well as acid-base properties of zeolites on the activity in Knoevenagel condensation were considered. Of particular interest was the role of Brønsted acid sites (BAS). The nature of basic sites and BAS played different roles depending on the methylene compound used in the Knoevenagel condensation. AP-modified zeolites were the most active in the condensation between benzaldehyde and ethyl cyanoacetate, in which, in the first step of the reaction AP abstracted hydrogen from methylene carbon in ethyl cyanoacetate. A different reaction pathway was postulated for the condensation with ethyl acetoacetate on the basis of the highest activity of unmodified zeolites and the relationship between benzaldehyde conversion and the number of BAS. For this reaction protonation of benzaldehyde was postulated as the initial step of the reaction.Publicación Ammonium acetate as a novel buffer for highly selective robust urinary HPLC-ICP-MS arsenic speciation methodology(Elsevier, 2021-01-01) Rodríguez, P. F.; López Colón, José Luis; Mendoza, J. L. de; Martín Aranda, Rosa MaríaAmmonium acetate is employed in order to develop a novel HPLC-ICP-MS arsenic speciation methodology applicable to six arsenic species, i.e, AC, AB, AsIII, AsV, DMA and MMA. The most predominant species in the toxicological field are covered in a 30-min chromatogram with reproducible and repeatability peak area ratio. Moreover, typical problems from traditional methods are sorted out by using a robust, high-selective and 75ArCl+ interference-free methodology. Chromatographic and detector optimization ensures low LOQs for each species with acceptable precision and accuracy values obtained using four urinary arsenic speciation PTS enabling to be useful for sub ng mL−1 arsenic exposure assessments.Publicación Ordered mesoporous molecular sieves as active catalyts for the synthesis of 1,4-dihydropyridine derivatives(Elsevier, 2020-09-01) Calvino Casilda, Vanesa; Martín Aranda, Rosa MaríaResearch on heterocyclic compounds with biological and pharmacological activity continues to arouse great interest. The study of 1,4-dihydropyridines (1,4-DHPs) is of particular interest in the pharmaceutical field due to their important applications as calcium channel antagonists for the treatment of heart diseases. The implementation of novel heterogeneous catalysts to optimize Hantzsch synthesis, such as ordered mesoporous molecular sieves, is an efficient and eco-friendly proposal that still requires a lot of work. The remarkable features of ordered mesoporous molecular sieves, such as high surface area, tailored porosity, chemical and thermal stability, among others, turn these materials into powerful solid catalysts capable of selectively leading the synthesis of 1,4-DHPs. In addition, the combination of ordered mesoporous molecular sieves and process intensification for the synthesis of 1,4-DHP derivatives is still a research field in development. Therefore, promote greener methodologies in the synthesis of 1,4-DHPs that can be extended to any organic synthesis in fine chemical production is an important goal yet to be achieved.Publicación SiO2 supported niobium oxides with active acid sites for the catalytic acetalization of glycerol(Elsevier, 2020-10-01) Kao, Li Chen; Kan, Wen Chen; Guerrero Pérez, María Olga; Bañares, Miguel Ángel; Ya Hsuan Liou, Sofía; Martín Aranda, Rosa MaríaThe silica supported niobium oxide catalysts with abundant acid active sites were successfully fabricated and demonstrated catalytic activity in the acetalization of glycerol with acetone to produce solketal. Although Niobium pentachloride which was used as the niobium precursor preferred to aggregate on the surface, the chemical vapor deposition method was introduced to remove the surface chloride. The synthesis parameter of the material affects the structure and the type of the supported niobium oxide on the carrier, and directly changes the amounts of catalytic sites. The effect of calcination temperature/time and loading amount of hydrated niobium oxide on the catalytic performance was investigated. The properties of acid sites on catalysts were characterized, and the catalytic process was directly observed by operando Raman. These in-situ experimental trials could provide deep insight to understand the catalytic mechanism.Publicación Developing strategies for the preparation of Co-carbon catalysts involved in the free solvent selective synthesis of aza-heterocycles(Elsevier, 2018-02) Godino Ojer, Marina; Pérez Cadenas, Agustín Francisco; Pérez Mayoral, María Elena; Martín Aranda, Rosa MaríaWe report herein different series of new zero valent Cobalt nanocarbons, as doped and supported aerogels, able to efficiently catalyze the reaction of 2-amino-5-chlorobenzaldehyde and -ketoesters, via Friedländer reaction. The reaction works under solvent-free and mild conditions affording yields over 80% in only 30 min of reaction time. The catalysts could be reused almost during two consecutive cycles without almost any activity loss. A comparative study between supported and doped-carbon aerogels, as catalysts highly efficient in the reaction, has allowed to stablish the relationship between the catalyst structure and the catalytic performance. At this regard, different parameters such as carbonization temperature and surface chemistry on the aerogels under study have been also explored. As a result, although the carbon matrix is involved in the reaction, the Co(0) nanoparticles on the carbon surface are the predominant active catalytic species. Oxygen functionalities on the oxidized samples in the surroundings of Co(0) nanoparticles probably prevent the access of the reagents, notably decreasing their catalytic performance.