Maria J. Climent

University of Valencia, Valenza, Valencia, Spain

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Publications (65)207.56 Total impact

  • ChemInform 05/2014; 45(18).
  • Maria J. Climent, Avelino Corma, Sara Iborra
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    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.
    ChemInform 04/2014; 45(13).
  • Maria J. Climent, Avelino Corma, Sara Iborra, Laura Martí
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    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.
    ChemSusChem 03/2014; · 7.48 Impact Factor
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    ACS Catalysis 02/2014; 4(3):870–891. · 5.27 Impact Factor
  • Applied Catalysis A: General. 01/2014; 481:27–38.
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    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.
    ChemCatChem 12/2013; 5(12). · 5.18 Impact Factor
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    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.
    ChemSusChem 09/2013; · 7.48 Impact Factor
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    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.
    ChemSusChem 06/2013; · 7.48 Impact Factor
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    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.
    ChemSusChem 01/2013; · 7.48 Impact Factor
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    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.
    The Journal of Physical Chemistry A 08/2012; 116(35):8807-14. · 2.77 Impact Factor
  • Maria José Climent, Avelino Corma, Sara Iborra
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    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.
    RSC Advances 12/2011; 2(1):16-58. · 3.71 Impact Factor
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    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.
    Physical Chemistry Chemical Physics 08/2011; 13(38):17255-61. · 3.83 Impact Factor
  • Maria J. Climent, Avelino Corma, Sara Iborra
    ChemInform 08/2011; 42(34).
  • Maria J. Climent, Avelino Corma, Sara Iborra
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    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.
    Green Chemistry 03/2011; 13(3). · 6.83 Impact Factor
  • Maria J Climent, Avelino Corma, Sara Iborra
    Chemical Reviews 02/2011; 111(2):1072-133. · 41.30 Impact Factor
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    ABSTRACT: The synthesis of a series of fine chemicals (4-(4-methoxyphenyl)-2-butanone, 4-(6,6-dimethylbicyclo[3,1,1]hept-2-en-2-yl)-2-butanone, and 2-cyclopentylcylopentanone) has been performed through a simple process that involves one-pot multi-step reactions (condensation–dehydration–reduction) using multifunctional base–acid-metal catalysts. The E factor for the specific process, as well as for the global process that includes the manufacturing of the reactants, has been calculated and compared with those obtained using conventional methods. In various cases, it is demonstrated that by means of process intensification with multifunctional solid catalysts, it is possible to decrease the E factor by one order of magnitude or more with respect to any of the manufacturing routes reported to date.
    Green Chemistry 01/2010; 12(1). · 6.83 Impact Factor
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    ABSTRACT: Synthesis of glycerol carbonate has been performed by transesterification of ethylene carbonate with glycerol catalyzed by basic oxides (MgO, and CaO), and mixed oxides (Al/Mg, Al/Li) derived from hydrotalcites. The results showed that the optimum catalyst in terms of activity and selectivity is a strong basic Al/Ca-mixed oxide (AlCaMO) which is able to catalyze the reaction at low temperature (35°C), and low catalyst loading (0.5wt%) giving high glycerol conversions with 98% selectivity to glycerol carbonate. When the synthesis of glycerol carbonate was carried out by carbonylation of glycerol with urea, the results showed that balanced bifunctional acid–base catalysts where the Lewis acid activates the carbonyl of the urea and the conjugated basic site activates the hydroxyl group of the glycerol were the most active and selective catalysts.
    Journal of Catalysis - J CATAL. 01/2010; 269(1):140-149.
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    ABSTRACT: ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
    ChemInform 01/2010; 41(1).
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    ABSTRACT: Bifunctional acid-base ionic liquid organocatalysts with different distances between the two sites have been synthesised, and their activity for the Knoevenagel condensation has been tested. As has been found to be the case with enzymes, the distance between the acidic and basic sites determines the activity of the bifunctional organocatalyst, and at the optimal distance the reaction rate increases by two orders of magnitude with respect to the purely acidic or basic counterpart organocatalysts. The experimental results have been rationalised through the study of the reaction mechanism of the Knoevenagel condensation between malononitrile and benzaldehyde by means of DFT calculations. It has been found that it consists of two consecutive steps. First, deprotonation of malononitrile on the basic site to obtain a methylene carbanion intermediate takes place, and second, co-adsorption and activation of benzaldehyde on the acid centre of this intermediate followed by the C-C bond-formation reaction. The calculations and the kinetic study indicate that there is an inversion of the rate-controlling step when the distance between the acidic and the basic sites is modified, with a direct implication on the reaction rate.
    Chemistry 12/2009; 16(4):1221-31. · 5.93 Impact Factor
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    ABSTRACT: Substituted 1,5-benzodiazepines are selectively synthesized in one pot from substituted nitroaromatics and ketones. The reaction is performed in the presence of hydrogen and in the absence of solvent by using a bifunctional solid catalyst with a chemoselective hydrogenation functional group capable of reducing the nitro group to a diamino group and an acid functional group, which catalyzes the cyclocondensation of the amino group with the ketone.
    Chemistry 08/2009; 15(35):8834-41. · 5.93 Impact Factor

Publication Stats

300 Citations
207.56 Total Impact Points


  • 1991–2014
    • University of Valencia
      Valenza, Valencia, Spain
  • 1989–2014
    • Polytechnical University of Valencia
      • • Institute of Chemical Technology (ITQ)
      • • Department of Chemistry
      Valenza, Valencia, Spain
  • 2013
    • Instituto de Química Avanzada
      Barcino, Catalonia, Spain
  • 1991–1995
    • Instituto Universitario de Tecnología de Valencia
      Valencia, Estado Carabobo, Venezuela
  • 1987
    • Universidad Politécnica de Madrid
      Madrid, Madrid, Spain