Maria J Climent

Universitat Politècnica de València, Valenza, Valencia, Spain

Are you Maria J Climent?

Claim your profile

Publications (76)382.24 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: The dehydration of aldoximes to the corresponding nitriles can be performed with excellent activity and selectivity by using iron trimesate as a homogeneous catalyst. Iron trimesate has been heterogenized by synthesizing metal-organic frameworks (MOFs) from iron trimesate, that is, Fe(BTC), and MIL-100 (Fe). These materials were active and selective aldoxime dehydration catalysts, and postsynthesis-treated MIL-100 (Fe) produced the desired nitriles with 100 % conversion and selectivities >90 % under mild reaction conditions and in short reaction times. X-ray photoelectron spectroscopy showed the presence of different Fe species in the catalyst, and in situ IR spectroscopy combined with catalytic results indicates that the catalytic activity is associated with Fe framework species. The postsynthesis-treated MIL-100 (Fe)-NH4 F can be recycled several times and has an excellent reaction scope, which gives better catalytic results than other solid acid or base catalysts. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
    No preview · Article · Aug 2015 · ChemSusChem
  • [Show abstract] [Hide abstract]
    ABSTRACT: N-substituted-5-methyl-2-piyrrolidones have been obtained by reductive amination of ethyl levulinate with amines in the presence of H2 as reducing agent under solvent-free conditions. The process involves as a first step the formation of an imine intermediate followed by hydrogenation of the imine group and subsequent cyclization into pyrrolidone. Pt/TiO2 with Pt crystal faces decorated with TiOx is a very active and chemoselective catalyst, being possible to achieve high conversion and selectivity to the corresponding N-substituted-5-methyl-2-pyrrolidones even when other groups susceptible of hydrogenation such as vinyl, carbonyl, or cyano groups are present in the amine moiety. A kinetic study showed that the reaction-controlling step is the formation of the imine intermediate. The rate of formation is enhanced by the presence of protonic acid sites generated on the support by hydrogen dissociation on the metal, resulting in a true bifunctional catalyst for the reaction.
    No preview · Article · Aug 2015 · ACS Catalysis
  • M. J. Climent · A. Corma · S. Iborra · L. Martí
    [Show abstract] [Hide abstract]
    ABSTRACT: 2′-Aminochalcones of pharmaceutical and commercial interest have been obtained in high yields and selectivities through a one-pot process using a bifunctional heterogeneous catalyst bearing base and metal active sites. This is a physical mixture material formed by a high-surface-area MgO and Pt on TiO2. The process involves as the first step the Claisen–Schmidt condensation between o-nitroacetophenone and benzaldehyde derivatives on the basic catalytic function. This is followed by a chemoselective hydrogenation of the nitro group in the presence of the carbonyl and double-bond carbon–carbon groups within the molecule. Using the bifunctional catalyst and the reaction system proposed here, it is possible to produce, under mild reaction conditions and short reaction times, 2′-aminochalcones with higher yields and selectivities than those obtained by conventional multistep methods.Keywords: heterogeneous catalysis; 2′-aminochalcones; fine chemicals; cascade process; bifunctional catalyst
    No preview · Article · Jan 2015 · ACS Catalysis
  • Maria J. Climent · Sara Iborra · Maria J. Sabater · Juan D. Vidal
    [Show abstract] [Hide abstract]
    ABSTRACT: A bifunctional organocatalyst with ionic liquid properties and with an optimized distance between the acid and basic sites efficiently activates electron deficient olefins for 1,4 conjugated addition, which can be incorporated in different one-pot transformations for the preparation of cyclic and acyclic compounds of biological and synthetic interest. More specifically, the catalyst can be successfully applied for different carbon-carbon (C-C) and carbon-heteroatom (C-N, C-O, C-S) bond forming reactions integrated in a cascade sequence. The activity of the organocatalyst has been compared with that of structurally related monofunctional and bifunctional catalysts. The most attractive features of this procedure are the high atom economy and the use of inexpensive starting materials as well as the use of an environmentally friendly catalyst that can be easily recovered due to its ionic liquid properties.
    No preview · Article · Jul 2014 · Applied Catalysis A General
  • Maria J. Climent · Avelino Corma · Sara Iborra · Maria J. Sabater

    No preview · Article · May 2014 · ChemInform
  • Maria J. Climent · Avelino Corma · Sara Iborra
    [Show abstract] [Hide abstract]
    ABSTRACT: In this work some relevant processes for the preparation of liquid hydrocarbon fuels and fuel additives from cellulose, hemicellulose and triglycerides derived platform molecules are discussed. Thus, it is shown that a series of platform molecules such as levulinic acid, furans, fatty acids and polyols can be converted into a variety of fuel additives through catalytic transformations that include reduction, esterification, etherification, and acetalization reactions. Moreover, we will show that liquid hydrocarbon fuels can be obtained by combining oxygen removal processes (e.g. dehydration, hydrogenolysis, hydrogenation, decarbonylation/descarboxylation etc.) with the adjustment of the molecular weight via C–C coupling reactions (e.g. aldol condensation, hydroxyalkylation, oligomerization, ketonization) of the reactive platform molecules.
    No preview · Article · Apr 2014 · ChemInform
  • Maria J. Climent · Avelino Corma · Sara Iborra · Laura Martí
    [Show abstract] [Hide abstract]
    ABSTRACT: 1,5-Benzothiazepines derivatives were obtained first by starting from 1,3-diphenylpropenone derivatives (chalcones) and 2-aminothiophenol by using aluminosilicate solid catalysts. However, diffusional limitations and the strong adsorption of products on the catalyst are deleterious for catalyst activity and life. Then a structured amorphous mesoporous catalyst with large pores and mild acidity that works at higher temperatures allowed us to obtain high conversions (99 %) and selectivities (98 %) of the desired product. A one-pot synthesis of 1,5-benzothiazepines that starts from benzaldehyde, acetophenone, and 2-aminothiophenol with 95 % yield was performed by combining optimized solid base and acid catalysts in batch mode as well as in a continuous-flow reactor system. Much better conversion and selectivity as well as process intensification has been achieved with the structured mesoporous materials by avoiding intermediate and final neutralization and purification steps required in the synthesis reported previously that uses homogeneous catalysts.
    No preview · Article · Apr 2014 · ChemSusChem
  • Source
    Maria J. Climent · Avelino Corma · Sara Iborra · Maria J. Sabater

    Full-text · Article · Feb 2014 · ACS Catalysis
  • Source
    Karen S Arias · Maria J Climent · Avelino Corma · Sara Iborra
    [Show abstract] [Hide abstract]
    ABSTRACT: A new class of biodegradable anionic surfactants with structures based on 5-alkoxymethylfuroate was prepared starting from 5-hydroxymethylfurfural (HMF), through a one-pot-two-steps process which involves the selective etherification of HMF with fatty alcohols using heterogeneous solid acid, followed by a highly selective oxidation of the formyl group with a gold catalyst. The etherification step was optimized using aluminosilicates as acid catalysts with different pore topologies (H-Beta, HY, Mordenite, ZSM-5, ITQ-2, and MCM-41), different active sites (Bronsted or Lewis) and different adsorption properties. It was shown that highly hydrophobic defect-free H-Beta zeolites with Si/Al ratios higher than 25 are excellent acid catalysts to perform the selective etherification of HMF with fatty alcohols, avoiding the competitive self-etherification of HMF. Moreover, the 5-alkoxymethylfurfural derivatives obtained can be selectively oxidized to the corresponding furoic salts in excellent yield using Au/CeO2 as catalyst and air as oxidant, at moderated temperatures. Both H-Beta zeolite and Au/CeO2 could be reused several times without loss of activity.
    Preview · Article · Jan 2014 · ChemSusChem
  • [Show abstract] [Hide abstract]
    ABSTRACT: The aim of this work was to assess the impact of innovative teaching methodology, learning centered, on learning strategies and academic achievement of three groups of students in Chemistry. They were 1st year students of Engineering at the Polytechnic University of Valencia. A pre-experimental design with pretest and posttest measures, taken by the questionnaire CEVEAPEU, was used. The sample consisted of 74 students in three groups, whose teachers agreed on the methodology they used. The teaching methods included expository methodology, questions, problem solving, development of a monograph, laboratory practices, team work, etc. They used a system of assessment that returned formative feedback to students. Significant improvements in learning strategies in the posttest were found, both overall test scores and scores of the scales and subscales (metacognitive strategies, search strategies and selection of information, and processing strategies and use of information), and better grades in that subject than in the others of the course. The positive results encouraged researchers to continue in this direction.
    No preview · Article · Jan 2014 · Revista Espanola de Pedagogia
  • [Show abstract] [Hide abstract]
    ABSTRACT: Process intensification by using well-defined solid catalysts able to perform one-pot multistep reactions is one of the open fronts in heterogeneous catalysis. This is even more relevant if new, more efficient synthesis routes are open. Herein, a gold catalyst was used to synthesize benzimidazoylquinoxalines compounds by two efficient and selective novel methods in a multistep one-pot methodology. The first method involved the synthesis of benzimidazoylquinoxaline compounds with the same substituents in both heterocycles through oxidation–cyclization of glycerol with o-phenylenediamine derivatives, whereas the second one allowed the synthesis of benzimidazoylquinoxalines compounds with different substituents in each aromatic ring through coupling of o-phenylenediamine derivatives with glyceraldehyde in a first stage to produce the benzimidazol compound as an intermediate, followed by an oxidation–cyclization with another o-phenylenediamine compound in a second stage. Both stages were performed by using gold nanoparticles supported on nanoparticulated ceria (Au/CeO2) as the catalyst and air as the oxidant, in absence of any homogeneous reagent. A reaction mechanism has been proposed.
    No preview · Article · Dec 2013 · ChemCatChem
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Se pretendía evaluar el impacto de metodología docente innovadora, centrada en el aprendizaje, sobre las estrategias de aprendizaje de tres grupos de estudiantes de Química, de 1º curso de Ingeniería de la Universidad Politécnica de Valencia. Se utilizó un diseño preexperimental, con medidas de pretest y postest, tomadas mediante el cuestionario CEVEAPEU. La muestra estaba constituida por 74 alumnos de tres grupos, cuyos profesores consensuaron la metodología a utilizar, que comportaba metodología expositiva reducida a lo preciso, preguntas, resolución de problemas, elaboración de una monografía, exposiciones orales, prácticas de laboratorio, trabajo en grupo, y un sistema de evaluación que hacía uso de procedimientos formativos que devolvían feedback a los estudiantes (valoración de problemas resueltos, autoevaluación mediante el uso de la plataforma de e-learning de la universidad, evaluación de las exposiciones orales de clase, observación, pruebas escritas, etc.). Se encontraron mejoras significativas en las estrategias de aprendizaje en el postest, tanto en la puntuación global del cuestionario como en las puntuaciones de las escalas (estrategias relacionadas con el procesamiento de la información) y subescalas (estrategias metacognitivas, estrategias de búsqueda y selección de información, y estrategias de procesamiento y uso de la información). Los resultados, positivos, animan a continuar en esta dirección.
    Full-text · Conference Paper · Jul 2013
  • [Show abstract] [Hide abstract]
    ABSTRACT: Glycerol carbonate esters (GCEs), which are valuable biomass-derivative compounds, have been prepared through the direct esterification of glycerol carbonate and long organic acids with different chain lengths, in the absence of solvent, and with heterogeneous catalysts, including acidic-organic resins, zeolites, and hybrid organic-inorganic acids. The best results, in terms of activity and selectivity towards GCEs, were obtained using a Nafion-silica composite. A full reaction scheme has been established, and it has been demonstrated that an undesired competing reaction results in the generation of glycerol and esters derived from a secondary hydrolysis of the endocyclic ester group, which is attributed to water formed during the esterification reaction. The influence of temperature, substrate ratio, catalyst-to-substrate ratio, and the use of solvent has been studied and, under optimized reaction conditions and with the adequate catalyst, it was possible to achieve 95 % selectivity for the desired product at 98 % conversion. It was demonstrated that the reaction rate decreased as the number of carbon atoms in the linear alkyl chain of the carboxylic acid increased for both p-toluenesulfonic acid and Nafion-silica nanocomposite (Nafion SAC-13) catalysts. After fitting the experimental data to a mechanistically based kinetic model, the reaction kinetic parameters for Nafion SAC-13 catalysis were determined and compared for reactions involving different carboxylic acids. A kinetic study showed that the reduced reactivity of carboxylic acids with increasing chain lengths could be explained by inductive as well as steric effects.
    No preview · Article · Jul 2013 · ChemSusChem
  • [Show abstract] [Hide abstract]
    ABSTRACT: The selective acetalization of 5-hydroxymethylfurfural (HMF) with long-chain alkyl alcohols has been performed to obtain precursors of molecules with surfactant properties. If direct acetalization of HMF with n-octanol is performed in the presence of strong acids (homogeneous and heterogeneous catalysts), an increase in etherification versus acetalization occurs. Beta zeolite catalyzes both reactions. However, if the acidity of a zeolite (Beta) was controlled by partial exchange of H(+) with Na(+) , the dioctyl acetal of HMF can be achieved in 95 % yield by transacetalization. It is possible to achieve a high yield in a very short reaction time through a two-step one-pot process, which includes the synthesis of the dimethyl acetal of HMF followed by transacetalization with n-octanol. The one-pot process could be extended to other alcohols that contain 6-12 carbon atoms to afford 87-98 % yield of the corresponding dialkyl acetal with a selectivity higher than 96 %. The optimized catalyst with an adequate Na content (1.5NaBeta) could be recycled without loss of activity or selectivity.
    No preview · Article · Jan 2013 · ChemSusChem
  • [Show abstract] [Hide abstract]
    ABSTRACT: Excited-state interactions between (S)- or (R)-flurbiprofen ((S)- or (R)-FBP) and thymidine (dThd) covalently linked in dyads 1 or 2 have been investigated. In both dyads, the only emitting species is (1)FBP*, but with a lower fluorescence quantum yield (ϕ(F)) and a shorter fluorescence lifetime (τ(F)) than when free in solution. These results indicate that dynamic quenching occurs either by electron transfer or via exciplex formation, with FBP as the charge-donating species. In acetonitrile, both mechanisms are favored, while in dioxane exciplex formation is predominating. Isomer 1 displays lower values of ϕ(F) and τ(F) than its analogue 2, indicating that the relative spatial arrangement of the chromophores plays a significant role. The triplet quantum yields (ϕ(T)) of 1 and 2 are significantly higher than the expectations based solely on (1)FBP*-dThd intersystem crossing quantum yields (ϕ(ISC)), with ϕ(T) (1) > ϕ(T) (2). This can be explained in terms of intramolecular charge recombination at the radical ion pairs and/or the exciplexes, which would be again dependent on geometrical factors. The triplet lifetimes (τ(T)) of (3)FBP*-dThd and free (3)FBP* are similar, indicating the lack of excited-state interactions at this stage. The FBP-dThd dyads could, in principle, constitute appropriate model systems for the elucidation of the excited-state interactions in noncovalent DNA-ligand complexes.
    No preview · Article · Aug 2012 · The Journal of Physical Chemistry A
  • Maria José Climent · Avelino Corma · Sara Iborra
    [Show abstract] [Hide abstract]
    ABSTRACT: Organic synthesis performed through multicomponent reactions is an attractive area of research in organic chemistry. Multicomponent reactions involve more than two starting reagents that couple in an exclusive ordered mode under the same reaction conditions to form a single product which contains the essential parts of the starting materials. Multicomponent reactions are powerful tools in modern drug discovery processes, because they are an important source of molecular diversity, allowing rapid, automated and high throughput generation of organic compounds. This review aims to illustrate progress in a large variety of catalyzed multicomponent reactions performed with acid, base and metal heterogeneous and homogeneous catalysts. Within each type of multicomponent approach, relevant products that can be obtained and their interest for industrial applications are presented.
    No preview · Article · Dec 2011 · RSC Advances
  • [Show abstract] [Hide abstract]
    ABSTRACT: A series of bifunctional organic catalysts containing acid and basic sites with ionic liquid characteristics have been prepared and their catalytic activity and reaction coordinate for aldol and Knoevenagel condensations have been compared. While the only factor controlling catalyst activity for the Knoevenagel condensation was the distance between the acid and base sites, the spatial orientation of the organocatalyst is also key to achieve high activity and selectivity in the Claisen-Schmidt condensation. Mechanistic studies based on theoretical DFT calculations show that the acid-base bifunctional organocatalyst follows a mechanism inspired in natural aldolases for the synthesis of trans-chalcones, being able to produce a large variety of these compounds of industrial interest. The combination of the acid-base pairs within the proper geometry and the ionic liquid nature makes this catalyst active, selective and recyclable.
    No preview · Article · Aug 2011 · Physical Chemistry Chemical Physics
  • Maria J. Climent · Avelino Corma · Sara Iborra
    [Show abstract] [Hide abstract]
    ABSTRACT: IntroductionAcid-Catalyzed ReactionsBase-Catalyzed ReactionsSummary and OutlookReferences
    No preview · Article · Aug 2011 · ChemInform
  • Maria J. Climent · Avelino Corma · Sara Iborra
    [Show abstract] [Hide abstract]
    ABSTRACT: In this Critical Review, we discuss how carbohydrates can be transformed into a variety of chemicals through heterogeneous catalysis. We focus particularly on oxidation, reduction and dehydration of hexoses, as well as one-pot reactions of di- and polysaccharides. Most of the reactions involve heterogeneous catalysts, although some interesting homogeneously catalyzed processes are also included.
    No preview · Article · Mar 2011 · Green Chemistry
  • Maria J Climent · Avelino Corma · Sara Iborra
    [Show abstract] [Hide abstract]
    ABSTRACT: The success of a given multistep sequential or multicomponent process requires a balance of equilibria and a suitable sequence of reversible and irreversible steps. The simplest way to perform a multistep synthesis is to perform the consecutive steps not only in the same vessel but also under the same reaction conditions. Substituted phthalides are an important class of natural compounds with a variety of important biological properties, whose heterocyclic motif appears in many bioactive compounds. The synthesis is based in two consecutive steps which involves first the condensation of the phthalaldehydic acid with the ketone following the regular mechanism of an acidcatalyzed aldol condensation, giving an aldol intermediate which subsequently lactonize to the target compound. The heptanal self-condensation can be avoided, to some extent, by maintaining a very low concentration of heptanal with respect to benzaldehyde in the reaction mixture.
    No preview · Article · Feb 2011 · Chemical Reviews

Publication Stats

3k Citations
382.24 Total Impact Points

Institutions

  • 1986-2015
    • Universitat Politècnica de València
      • • Institute of Chemical Technology (ITQ)
      • • Department of Chemistry
      Valenza, Valencia, Spain
  • 1991-2014
    • University of Valencia
      Valenza, Valencia, Spain
  • 1996-2009
    • Instituto Universitario de Tecnología de Valencia
      Valencia, Carabobo, Venezuela
  • 2004
    • Instituto de Química Avanzada
      Barcino, Catalonia, Spain
  • 1987
    • Universidad Politécnica de Madrid
      Madrid, Madrid, Spain