An Acyl-NHC Osmium Cooperative System: Coordination of Small Molecules and Heterolytic B–H and O–H Bond Activation

The hexahydride complex OsH6(PiPr3)2 (1) activates the C–OMe bond of 1-(2-methoxy-2-oxoethyl)-3-methylimidazolium chloride (2), in addition to promoting the direct metalation of the imidazolium group, to afford a five-coordinate OsCl(acyl-NHC)(PiPr3)2 (3) compound. The latter coordinates carbon monoxide, oxygen, and molecular hydrogen to give the corresponding carbonyl (4), dioxygen (5), and dihydrogen (6) derivatives. Complex 3 also promotes the heterolytic bond activation of pinacolborane (HBpin), using the acyl oxygen atom as a pendant Lewis base. The hydride ligand and the Bpin substituent of the Fischer-type carbene of the resulting complex 7 activate the O–H bond of alcohols and water. As a consequence, complex 3 is a metal ligand cooperating catalyst for the generation of molecular hydrogen, by means of both the alcoholysis and hydrolysis of pinacolborane, via the intermediates 7 and 6.

2-Aminobenzimidazole Organocatalyzed Asymmetric Amination of Cyclic 1,3-Dicarbonyl Compounds

The use of a trans-cyclohexanediamine benzimidazole derivative as a hydrogen-bond catalyst for the electrophilic amination of cyclic 1,3-dicarbonyl compounds is herein presented. High yields and enantioselectivities varying from moderate to excellent are generally obtained using mild reaction conditions and as low as 1 mol% of catalyst loading.

Grado de interiorización de los sistemas de gestión medioambiental: una revisión de la literatura

El objetivo de este trabajo es analizar las principales características de los trabajos sobre interiorización de las normas de gestión medioambiental que fueron identificados a partir de una búsqueda electrónica en las bases de datos Web of Science, Science Direct, ProQuest y Emerald. Estos trabajos muestran que las empresas pueden tener un mayor o menor compromiso con los requisitos de una norma de gestión medioambiental, lo que puede llevar a niveles heterogéneos de interiorización e implantación. Además, los resultados de estos trabajos muestran que una mayor interiorización conlleva un mejor rendimiento medioambiental.

Mesoporous Metal Complex–Silica Aerogels for Environmentally Friendly Amination of Allylic Alcohols

Two series of mesoporous hybrid iron(III) complex–silica aerogels were prepared in one-pot synthesis by using the sol–gel coordination chemistry approach. The use of the ligands 3-(2-aminoethylamino)propyltrimethoxysilane and 2-(diphenylphosphino)ethyltriethoxysilane, both with terminal triethoxysilyl groups, were used to incorporate metal complexes in situ into the framework of silica, through their co-condensation with a silicon alkoxide during the aerogel formation. This methodology yielded optically translucent hybrid mesoporous gels with homogeneous metal incorporation and excellent textural properties. The catalytic performance of these materials was tested in the direct amination of allylic alcohols in water as a target reaction, with activities comparable or even higher than those corresponding to the homogeneous iron(III) complex. Furthermore, these catalysts were stable and maintained their catalytic activity after six reaction cycles.

Organocatalytic Asymmetric α-Chlorination of 1,3-Dicarbonyl Compounds Catalyzed by 2-Aminobenzimidazole Derivatives

Bifunctional chiral 2-aminobenzimidazole derivatives 1 and 2 catalyze the enantioselective stereodivergent α-chlorination of β-ketoesters and 1,3-diketone derivatives with up to 50% ee using N-chlorosuccinimide (NCS) or 2,3,4,4,5,6-hexachloro-2,5-cyclohexadien-1-one as electrophilic chlorine sources.

Experiencia de la Universidad de Alicante en el uso de la docencia basada en proyectos para la enseñanza de diseño de reactores

En la Universidad de Alicante se viene aplicando el método de aprendizaje basado en proyectos (ABP) en la asignatura de “Diseño de reactores heterogéneos” desde hace varios años. Los profesores están sumamente contentos con este método, pues reciben un feedback muy interesante por parte del alumnado y se discrimina perfectamente los alumnos valiosos.

Impregnated palladium on magnetite as catalyst for direct arylation of heterocycles

Palladium impregnated on magnetite is an efficient, cheap and easy to prepare catalyst for the direct arylation of heterocycles. Good yields are afforded under relatively mild conditions and a broad substrate scope is evident. The catalyst is regioselective in many cases, affording arylated products, at the C2- or C3-position (depending of the heterocycle used). The methodology can be extended to prepare chromenes through an intramolecular direct arylation reaction. Some evidence is provided for two catalyst deactivation pathways, which prevents efficient recycling.

Cross-dehydrogenative coupling reaction using copper oxide impregnated on magnetite in deep eutectic solvents

The synthesis of different tetrahydroisoquinolines using choline chloride : ethylene glycol as a deep eutectic solvent (DES) and copper(II) oxide impregnated on magnetite as a catalyst has been accomplished successfully. The copper catalyst amount is the lowest loading ever reported. The presence of DES showed to be essential since the reaction in the absence of this medium did not proceed. A direct proportional relationship was found between the conductivity of DES medium and the yield obtained. The DES and the catalyst could be reused up to ten times without any detrimental effect on the yield of the reaction, with the aerobic conditions making the protocol highly sustainable, where the only waste is water.

Pursuing Chemical Efficiency by Using Supported Organocatalysts for Asymmetric Reactions under Aqueous Conditions

Over the past decade, a great effort has been made by the chemical community to improve the efficiency of organic transformations and allow sustainable processes. Merging the use of supported and recyclable organocatalysts and aqueous conditions for the asymmetric synthesis of valuable molecules, has led to outstanding contributions in the area of green chemistry. Recent progresses in the field include the implementation of these methodologies in the large scale production of chiral molecules using automated flow chemistry.

Bio-renewable enantioselective aldol reaction in natural deep eutectic solvents

Among the deep eutectic solvents (DES), natural deep eutectic solvents (NADES) formed by D-glucose and racemic malic acid are suitable media to perform the enantioselective L-proline catalyzed intermolecular aldol reaction, creating simultaneously and selectively a C–C bond and a new stereocenter. The scope of the reaction was found to be broad, with products being obtained with good levels of diastereo- and enantioselectivities. Furthermore, when the reaction was performed at a large scale, the catalyst together with the reaction media can be recovered by simple water extraction and reused at least three times affording similar results. Therefore, the use of NADES as reaction media to carry out a VOC-free selective process has been demonstrated for the first time. The process is clean, cheap, simple and scalable and meets most of the criteria to be considered as a sustainable and bio-renewable process, with the reaction media and catalyst arising directly from Nature.

Palladium(II) oxide impregnated on magnetite as a catalyst for the synthesis of 4-arylcoumarins via a Heck-arylation/cyclization process

Heck-arylation/cyclization was achieved using heterogeneous palladium(II) oxide impregnated on magnetite catalyst (2.5 mol%) with a lower catalyst loading than that reported for similar processes. Ethanol was used as a non-toxic and bio-renewable solvent. Good yields were afforded using a broad range of substrates (40–98%). The catalyst could be partially recycled, and analyses confirmed the almost total reduction of palladium(II) oxide to palladium(0) as well as the iodine poissoning effect, which is the main barrier to complete recyclability.

Adaptación de la gestión de empresas turísticas al nuevo escenario del sector del turismo: especial referencia a la gestión hotelera

Resulte incuestionable que, en la actualidad, el Turismo constituye un complejo fenómeno con perfiles complejos y heterogéneos dentro del cual son abordados ámbitos muy diversos (económico, jurídico, político, cultural…). De forma inicial, dentro de la pluralidad de las relaciones que circunscriben el mismo, presentan especial transcendencia las conectadas, en mayor o menor grado, con la gestión y el alojamiento turístico. Lo que hace medio siglo resultaba inimaginable o, casi extravagante, constituye hoy una circunstancia común y frecuente en el escenario propuesto, de forma particular, dentro del complejo y escasamente analizado ámbito de la gestión hotelera. Al hilo de lo expresado, en este trabajo se analizará, partiendo del supuesto de que la colaboración interempresarial en el sector turístico puede sustentarse en capital o en relaciones contractuales, sus esenciales trazos conformadores (gestor hotelero y titular del hotel gestionado) sobre los cuales poder elaborar un concepto ordenado y de subsunción del mismo como paso previo para la fijación de su régimen jurídico básico. Con idéntico tenor, se discutirá la posibilidad de integración del hotel determinado en las grandes cadenas hoteleras, la utilización de su know-how estandarizado y marca propia. Finalmente, será estudiada su incidencia en las grandes cadenas hoteleras al objeto de valorar su expansión tanto desde un punto de vista nacional como internacional.

La Reacreditación en el Grado de Biología de la Facultad de Ciencias de la Universidad de Alicante

Implantación de los nuevos Grados, como sustitución de las Licenciaturas en los estudios universitarios, lleva consigo un proceso de Reacreditación, consistente en la revisión de una serie de parámetros de calidad, a realizar una vez terminada su implantación. Este proceso se ha desarrollado en tres ámbitos principales: la Gestión del Título, los Recursos de los que se dispone y, por último, los Resultados, y tiene como fin principal evaluar si los resultados obtenidos son adecuados para garantizar la continuidad de la impartición del Grado. El equipo de trabajo que ha llevado a cabo la revisión y ha puesto en marcha los procesos de mejora en el Grado de Biología de la Facultad de Ciencias de la Universidad de Alicante ha sido la Comisión de Título. La revisión que dicha Comisión ha realizado se ha centrado en evaluar la adquisición de competencias por parte de los estudiantes, en los recursos humanos y materiales que soportan el desarrollo del título, y en el análisis de la evolución de los resultados del mismo. Toda la información generada en este grupo de trabajo, ha sido volcada a la aplicación “AstUA” con la que se gestionan los programas de calidad de toda la Universidad de Alicante.

Princípios norteadores da gestão dos recursos hídricos no Brasil e no Estado de São Paulo em tempos de escassez

Este estudo visa apresentar os princípios gerais que regem a utilização dos recursos hídricos no Brasil e no Estado de São Paulo, destacando os instrumentos que regulamentam seu uso pelos múltiplos atores que dependem da água para a realização das mais variadas atividades, levando-se em consideração a legislação e demais normas e documentos elaborados e vigentes até o final do mês de maio de 2015. Será realizada pesquisa bibliográfica e documental e os dados serão tratados através da análise qualitativa de conteúdo. Afinal, como é a gestão da água no Estado de São Paulo e no Brasil, enquanto recurso, visando atender as necessidades heterogêneas dos atores que dele dependem para inúmeros usos? Buscar-se-á despertar o leitor para a relevância do tema neste momento em que atravessamos um cenário de escassez decorrente de uma série de fatores, dentre os quais destacam-se os gerenciais.

On the reactivity of naphthalene and biphenyl dianions: tying up loose ends concerning an SN2-ET dichotomy in alkylation reactions

Naphthalene and biphenyl dianions are interesting compounds that can be obtained by double reduction of the corresponding arenes in solution with certain alkali metals. These dianions are highly reactive and rather elusive species with very high laying and highly delocalized electrons. They share many aspects of the reactivity of the alkali metal they originated from and consequently behave primarily as strong electron transfer (ET) reagents. We report here kinetic evidence for a different type of reactivity in their alkylation reactions with alkyl fluorides. By using cyclopropylmethyl fluoride (c-C3H5CH2F) as a very fast radical probe, we were able to settle that this alkylation does not involve the classical electron transfer reaction followed by radical coupling between diffusing radicals, but supports the alternative SN2 concerted mechanism, discerning thus this mechanistic SN2-ET dichotomy.