Search results for "química orgánica"
showing 10 items of 87 documents
Complejos NHC–Metal en la funcionalización de hidrocarburos; procesos en batch y en flujo
2017
Desde hace muchos años, la catálisis juega un papel fundamental en distintas áreas, tanto del ámbito académico como del industrial, ya que facilita la síntesis de productos de gran impacto para la sociedad. Actualmente, industrias como la petroquímica, la farmacéutica, la cosmética, o la alimentaria, entre otras, dependen en gran medida de la catálisis. En la búsqueda de sistemas catalíticos óptimos que permitan llevar a cabo transformaciones eficientes, selectivas y que minimicen el costo energético y la producción de residuos, surgió la catálisis metálica, principalmente basada en complejos de metales de transición como catalizadores. Estos complejos han tenido una importante evolución, d…
Stereodifferentiation in the formation and decay of the encounter complex in bimolecular electron transfer with photoactivated acceptors.
2005
Experimental evidence has been obtained for the involvement of encounter complexes between both enantiomers of a π,π* triplet excited ketone and a chiral phenol or indole. Determination of the pre-equilibrium constants (KEC) and the intrinsic decay rate constants (kd) indicates a significant stereodifferentiation in both steps of the quenching process. Perez Prieto, Julia, Julia.Perez@uv.es ; Galian, Raquel Eugenia, Raquel.Galian@uv.es ; Morant Miñana, Maria Carmen, Maica.Morant@uv.es
Ionic liquids and microwave irradiation as synergistic combination for polar Diels–Alder reactions using properly substituted heterocycles as dienoph…
2012
For the DA reactions between nitropyrrole derivatives and isoprene, the combination of microwave irradiation and protic ionic liquid, has a notable synergistic effect. DFT calculations suggest that a supplementary energy ranking in the IR region of 1700-1400 cm-1 can favour the structural changes in the reactants to reach the TS. Fil: Mancini, Pedro Maximo Emilio. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Departamento de Química; Argentina Fil: Ormachea, Carla. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa F…
Triazolopyridines 22.1 Description of new 7,9-di(2-pyridyl)[1,2,3]triazolo[5',1':6,1]pyrido[3,2-d]pyrimidines
2002
The new heteroaromatic compounds, 7,9-di(2-pyridyl)[1,2,3]triazolo[5',1':6,1]pyrido[3,2-d] pyrimidines 11a-c, were synthesized in two steps from readily available triazolopyridines 1a-c. Regioselective lithiation of 1a-c followed by treatment with 2-cyanopyridine gave a mixture of compounds 5a-c, and 11a-c in moderate to low yields, together with gums. Similar reactions with the triazolopyridine 1d gave as the only identified compound the triazolopyridine derivative 5d. Abarca Gonzalez, Belen, Belen.Abarca@uv.es ; Ballesteros Campos, Rafael, Rafael.Ballesteros@uv.es ; Chadlaoui, Mimoun, michad@alumni.uv.es
Improved Regioselectivity in Pyrazole Formation through the Use of Fluorinated Alcohols as Solvents: Synthesis and Biological Activity of Fluorinated…
2008
The preparation of N-methylpyrazoles is usually accomplished through reaction of a suitable 1,3-diketone with methylhydrazine in ethanol as the solvent. This strategy, however, leads to the formation of regioisomeric mixtures of N-methylpyrazoles, which sometimes are difficult to separate. We have determined that the use of fluorinated alcohols such as 2,2,2-trifluoroethanol (TFE) and 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) as solvents dramatically increases the regioselectivity in the pyrazole formation, and we have used this modification in a straightforward synthesis of fluorinated analogs of Tebufenpyrad with acaricide activity. Fil: Fustero, Santos. Universidad de Valencia; España Fil…
Mechanisms of DNA damage by photoexcited 9-methyl-β-carbolines
2013
It has been well documented that β-carboline alkaloids, particularly the 9-methyl derivatives, are efficient photosensitizers. However, structure–activity relationships are missing and the photochemical mechanisms involved in the DNA photodamage still remain unknown. In the present work, we examined the capability of three 9-methyl-β-carbolines (9-methyl-norharmane, 9-methyl-harmane and 9-methylharmine) to induce DNA damage upon UVA excitation at physiological pH. The type and extent of the damage was analyzed together with the photophysical and binding properties of the β-carboline derivatives investigated. The results indicate that even at neutral pH most of the DNA damage is generated fr…
Natural eutectogels: sustainable catalytic systems for C–C bond formation reactions
2021
Natural eutecto gels were prepared combining properties of amino acids with the ones of deep eutectic solvents. Soft materials obtained were fully characterised determining the gel-sol transition temperatures and analysing mechanical and morphological features through rheological measurements and polarised optical microscopy. All eutecto gels were tested as catalytic reaction media for the enantioselective aldol reaction and, the best performing one was also used to carry out the Michael addition. In both cases, eutecto gels proved to have a great potential as sustainable reaction media, allowing to perform processes under mild conditions, obtaining excellent yields and, in some cases, also…
Reacciones de formación de enlaces C-C catalizadas por metales de transición y factores que les afectan
2015
La síntesis y funcionalización de compuestos carbonílicos ha atraído la atención de los químicos a lo largo del tiempo ya que el grupo carbonilo es una función muy versátil en química orgánica y está presente en numerosos compuestos con actividad biológica. Por su parte, las reacciones de acoplamiento cruzado de dos y tres componentes son metodologías que actualmente se aplican a nivel tanto académico como industrial debido a que requieren condiciones suaves de reacción, la extracción de los productos de la mezcla de reacción es fácil y los subproductos generados presentan una baja toxicidad. En este contexto, la aplicación de estas metodologías a la síntesis y funcionalización de compuesto…
Tuning the pore size from micro- to meso-porous in thermally stable aluminophosphates
1999
Thermally stable porous aluminophosphates (ICMUV-3) with P/Al molar ratios in the range 0.15 <= P/Al <= 0.75 and showing continuously adjustable pore sizes from 13 to 37 Å have been prepared through a surfactant-assisted procedure without changing the surfactant length and/or addition of organic expansors. Cabrera Medina, Saul, Saul.Cabrera@uv.es ; El Haskouri, Jamal, Jamal.Haskouri@uv.es ; Beltran Porter, Aurelio, Aurelio.Beltran@uv.es ; Beltran Porter, Daniel, Daniel.Beltran@uv.es ; Amoros del Toro, Pedro Jose, Pedro.Amoros@uv.es
Enzyme-catalysed transformations of ent-kaurane diterpenoids
2005
Several acetyl derivatives of linearol, atractyligenin and atractylitriol were obtained through enzyme-catalysed acetylation and deacetylation reactions. In most reactions lipases showed regio- and stereoselective behaviour, allowing a family of novel compounds to be prepared. Fil: Monsalve, Leandro Nicolas. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Unidad de Microanálisis y Métodos Físicos en Química Orgánica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Unidad de Microanálisis y Métodos Físicos en Química Orgánica; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y …