Catalytic Dehydrogenative Coupling of Hydrosilanes with Alcohols for the Production of Hydrogen On-demand: Application of a Silane/Alcohol Pair as a Liquid Organic Hydrogen Carrier

The compound [Ru(p-cym)(Cl)2(NHC)] is an effective catalyst for the room-temperature coupling of silanes and alcohols with the concomitant formation of molecular hydrogen. High catalyst activity is observed for a variety of substrates affording quantitative yields in minutes at room temperature and with a catalyst loading as low as 0.1 mol %. The coupling reaction is thermodynamically and, in the presence of a Ru complex, kinetically favourable and allows rapid molecular hydrogen generation on-demand at room temperature, under air, and without any additive. The pair silane/alcohol is a potential liquid organic hydrogen carrier (LOHC) for energy storage over long periods in a safe and secure way. Silanes and alcohols are non-toxic compounds and do not require special handling precautions such as high pressure or an inert atmosphere. These properties enhance the practical applications of the pair silane/alcohol as a good LOHC in the automotive industry. The variety and availability of silanes and alcohols permits a pair combination that fulfils the requirements for developing an efficient LOHC

An Expedient Method for the Umpolung Coupling of Enols with Heteronucleophiles

[EN] In this paper, we present an unprecedented and general umpolung protocol that allows the functionalization of silyl enol ethers and of 1,3-dicarbonyl compounds with a large range of heteroatom nucleophiles, including carboxylic acids, alcohols, primary and secondary amines, azide, thiols, and also anionic carbamates derived from CO2. The scope of the reaction also extends to carbon-based nucleophiles. The reaction relies on the use of 1-bromo-3,3-dimethyl-1,3-dihydro-1 lambda(3)[d][1,2]iodaoxole, which provides a key alpha-brominated carbonyl intermediate. The reaction mechanism has been studied experimentally and by DFT, and we propose formation of an unusual enolonium intermediate with a halogen-bonded bromide.The authors are grateful for support from the Swedish Research Council through Vetenskapsradet, and from the Goran Gustafsson Foundation. This project was also funded by the European Union's Horizon 2020 research and innovation programme under Grant Agreement 721223 and NordForsk through NordCO2 (85378)

A simple approach to understand solid state chemistry with the example of a piezoelectric material incorporated in a birthday card

EDULEARN17 Proceedings: 9th International Conference on Education and New Learning Technologies Dates (3-5 July, 2017, Barcelona, Spain),Advanced solid materials are present in a large quantity of fields of our quotidian live. All the electronic devices surrounding us, such as mobile phones, computers or appliances are made up of many different materials: ceramics, metals, polymers, etc. The recent development of advanced ceramic materials to be applied in electronic devices, which require high performances as well as relatively economic syntheses and environmentally friendly characteristics, is a wide field in Materials Chemistry. It is important to motivate students to this area, so that, they can understand the importance of the chemistry and the material science in our society. In the present contribution, we would like to relate our experience giving a comprehensive laboratory session intended for all undergraduate chemistry students. Piezoelectric compounds can be defined as materials that produce some electric charge when a mechanical stress is applied (direct effect) or suffer a mechanical deformation when an electric field is applied (reverse effect). These materials are used in several devices such as lighters, speakers, sensors or sonars. Lead zirconate titanate [Pb(Ti 1-x ,Zr x )O 3 ] (PZT) is the most studied and commercialized ceramic piezoelectric mat erial due to their excellent characteristics. Relation between structure -composition -properties of this material and its easy preparation makes it suitable to use in low value added devices. In this work, we propose an example to understanding this technology based on the components of a speaker of a musical birthday card, in particular the piezoelectric component, including the chemistry that is involved in these types of devices. Two common characterization techniques in Solid State Chemistry are also int roduced to the students: X -Ray Diffraction and Electron Microscopy. Moreover, the discovery by the students of the presence of this type of material in this simple device offers a possibility to motivate them to learn these sciences, and allow them to know the importance of the Solid State Chemistry and the Materials Science in our society. Different educational methodologies may be used to study and understand these materials with piezoelectric properties. Problem Based Learning (PBL) is a widely applied approach intended to encourage students to learn through the structured exploration of a research problem. Currently this particular system has become a valid teaching method in high schools, where students are encouraged to develop a real research project. The PBL methodology used in this work represents an improvement in the content of the knowledge while simultaneously it fosters the development of communication, problem -solving, and self -directed learning skills. This work can also be interesting for tea chers of inorganic chemistry and material science and undergraduate students owing to its pedagogical character

Enols and Allylic Alcohols as Building Blocks in Synthetic Organic Chemistry : Experimental and Theoretical Studies

The present thesis describes computational and experimental studies used to drive the reactivity of allylic and enol substrates towards new transformations. These synthetic methods give access to a number of organic molecules that may serve as important moieties in synthetic organic chemistry. Additionally, this thesis describes the synthesis of Metal-Organic Frameworks (MOFs) and their use in catalytic organic reactions.  The introductory chapter (Chapter 1) gives an overview of the concept of catalysis and its typologies, emphasizing those that have been used in the thesis. Moreover, synthetic procedures for the formation of MOFs and their use in catalysis are described. The importance and reactivity of allylic substrates are also presented. The chapter follows with a short introduction to hypervalent iodine and their reactivity. Finally, a brief description of computational studies and those used in this thesis are presented.  In Chapter 2, an umpolung protocol for the cross-nucleophile coupling of silyl enol ethers with heteronucleophiles mediated by an hypervalent iodine reagent has been explored (Paper I).  The mechanistic study of the reaction has been carried out employing DFT calculations and kinetic investigations. Together with deuterium labelling studies and kinetic simulations, DFT calculations have been used in Chapter 3 for the examination of the base-catalyzed [1,n]-proton shift in conjugated polyenyl ethers (Paper II).  Chapter 4 describes the synthesis of the family MIL-101(Cr) and MIL-101(Cr)-NH2 employing microwave-assisted methods. The method has been compared to the common solvothermal synthetic pathways using common characterization techniques for heterogeneous materials (Paper III).  Finally, Chapter 5 of this thesis describes the synthesis of a UiO-67 MOF containing a phosphazene superbase to study the effect of spatial confinement within a MOF on the stereospecific isomerization of allylic alcohols (Paper IV).Academic dissertation for the Degree of Doctor of Philosophy in Organic Chemistry</p

Reactivity of cubane-type molybdenum and tungsten cluster sulfides towards alkynes

Treball de Final de Grau en Química. Codi: QU0943. Curs acadèmic 2015-201

High Production of Hydrogen on Demand from Silanes Catalyzed by Iridium Complexes as a Versatile Hydrogen Storage System

The catalytic dehydrogenative coupling of silanes and alcohols represents a convenient process to produce hydrogen on demand. The catalyst, an iridium complex of the formula [IrCp*(Cl)(2)(NHC)] containing an N-heterocyclic carbene (NHC) ligand functionalized with a pyrene tag, catalyzes efficiently the reaction at room temperature producing H-2 quantitatively within a few minutes. As a result, the dehydrogenative coupling of 1,4-disilabutane and methanol enables an effective hydrogen storage capacity of 4.3 wt % that is as high as the hydrogen contained in the dehydrogenation of formic acid, positioning the silane/alcohol pair as a potential liquid organic hydrogen carrier for energy storage. In addition, the heterogenization of the iridium complex on graphene presents a recyclable catalyst that retains its activity for at least 10 additional runs. The homogeneous distribution of catalytic active sites on the basal plane of graphene prevents diffusion problems, and the reaction kinetics are maintained after immobilization

A General Method for alpha-Functionalization of Enol Derivatives through the Umpolung Cross-Nucleophile Coupling Mediated by a Single Iodine(III) Reagent

In this paper, we present an unprecedented and general umpolung protocol that allows the functionalization of silyl enol ethers and of 1,3-dicarbonyl compounds with a large range of heteroatomic nucleophiles, including carboxylic acids, alcohols, primary and secondary amines, azide, thiols, and also anionic carbamates derived from CO2. The scope of the reaction also extends to carbon-based nucleophiles. The reaction relies on the use of 1-bromo-3,3-dimethyl-1,3-dihydro-1delta3[d][1,2]iodaoxole, which provides a key alpha-brominated carbonyl intermediate. The reaction mechanism has been studied experimentaly and by DFT, and we propose formation of an unusual enolonium intermediate with a halogen-bonded bromide

Procedimiento para la producción y almacenamiento de hidrógeno mediante deshidrogenación catalítica, y uso de un catalizador de un metal de transición anclado sobre un soporte de un material de carbono para la obtención de hidrógeno mediante reacciones de deshidrogenación catalítica

La presente invención se refiere a un procedimiento para la producción y almacenamiento de hidrógeno mediante deshidrogenación catalítica basado en el uso de un catalizador de un metal de transición anclado sobre un soporte de un material de carbono. Adicionalmente, la presente invención también se refiere al uso de un catalizador de un metal de transición anclado sobre un soporte de un material de carbono para la obtención de hidrógeno mediante reacciones de deshidrogenación catalítica, preferiblemente, para el uso de dicho hidrógeno obtenido en una celda de combustible o un motor de combustión. [ES]The present invention relates to a method for the production and storage of hydrogen by means of catalytic dehydrogenation based on the use of a transition-metal catalyst anchored to a support made from a carbon material. In addition, the present invention also relates to the use of a transition-metal catalyst anchored to a support made from a carbon material in order to obtain hydrogen by means of catalytic dehydrogenation reactions, preferably in order for the hydrogen obtained to be used in a fuel cell or a combustion engine. [EN]Peer reviewedUniversitat Jaume I, Universidad de Zaragoza, Universitat Politècnica de València, Consejo Superior de Investigaciones Científicas (España)B2 Patente con examen previ