1,721,103 research outputs found
X-ray and molecular dynamics studies of butylammonium butanoate-water binary mixtures
No full textThe nanostructural organisation of mixtures of the ionic liquid (butylammonium butanoate) and water at several mole fractions of water has been investigated using small and wide angle X-ray scattering (S-WAXS) and molecular dynamics (MD) simulations. The presence of a first sharp diffraction peak (FSDP) in the pure ionic liquid has been observed, experimentally and theoretically, suggesting the possibility of segregation of domains of different polarity in the system. With increasing dilution in water, the prepeak is shifted towards smaller Q values, and becomes very weak, while the principal peak moves towards larger Q values. These phenomena suggest the disruption of the hydrogen-bonded network of the ionic liquid, primarily through hydrogen bonding of the anion to water, a conclusion supported by MD simulations
Quinine based ionic liquids: A tonic for base instability
No full textSix basic ionic liquids were synthesised from the natural molecule quinine, including one room temperature ionic liquid. The thermal properties were studied and the basicity analysed by Hammett measurements. The properties are discussed in relation to the crystal structure of one of the salts, [C4Qn][NTf2] (2c) and electron density models generated using Spartan. The ionic liquids were shown to catalyse the Knoevenagel condensation of Malononitrile and Benzaldehyde.</p
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Criticality of the [C(4)mim] [BF4] plus water system
No full textA study of the behavior of the response functions of the [C(4)mim][BF4] + water ionic binary solution near its liquid-liquid critical point at atmospheric pressure is presented. Phase equililibrium temperatures, which allow to obtain the critical coordinates of this system, are determined. Measurements of the isobaric heat capacity per unit volume in the critical region indicate Ising-like behavior. The slope of the critical line, (dT/dp)(c), is estimated by means of Prigogine and Defay's equation using experimentally determined excess volumes and excess enthalpies as a function of temperature. (dT/dp)(c) is found to be near zero. The consequences of this fact for the global critical behavior of second-order volumetric derivatives are discussed
Supported ionic liquid-phase (SILP) catalysis – Heterogenization of homogeneous rhodium phosphine catalysts
No full textIonic Liquids Uncoiled: Critical Expert Overviews
No full textIonic Liquids UnCOILed presents decisively important reviews on new processes and recent developments in ionic liquid technology with an emphasis on commercial applications in which ionic liquids are replacing, or may replace, processes currently using conventional solvents. Ranging from applied to theoretical, synthetic to analytical, and biotechnological to electrochemical, the book features eleven chapters written by an international group of key academic and industrial chemists, exercising the judicious evaluation which they are uniquely qualified to do. This book is a must for R and D chemists in industrial, governmental and academic laboratories, and for commercial developers of environmentally-friendly, sustainable processes. </p
Engineering Simulations
No full textOver recent years, ionic liquids have emerged as a class of novel fluids that have inspired the development of a number of new products and processes. The ability to design these materials with specific functionalities and properties means that they are highly relevant to the growing philosophy of chemical-product design. This is particularly appropriate in the context of a chemical industry that is becoming increasingly focussed on small-volume, high-value added products with relatively short times to market. To support such product and process development, a number of tools can be utilised. A key requirement is that the tool can predict the physical properties and activity coefficients of multi-component mixtures and, if required, model the process in which the materials will be used. Multi-scale simulations that span density functional theory (DFT) to process-engineering computations can address the relevant time and length scales and have increased in usage with the availability of cheap and powerful computers. Herein we will discuss the area of engineering calculations relating to the design of ionic liquid processes, that is, the computational tools that bridge this gap and allow for process simulation tools to utilise and assist in the design of ionic liquids. It will be shown that, at present, it is possible to use available tools to estimate many important properties of ionic liquids and mixtures containing them with a sufficient level of accuracy for preliminary design and selection.</p
Phase behavior and thermodynamic properties of ionic liquids, ionic liquid mixtures, and ionic liquid solutions
No full textAn overview of experimental and theoretical studies recently performed in the Oeiras/Lisbon laboratories is provided. Typical showcase examples of UCST demixing of ionic liquid solutions are presented and discussed. Co-solvency, pressure, and isotope effects were investigated. In order to rationalize the observed effects, a phenomenological g(E)-model was successfully applied, which permitted us to establish strong links between phase behavior and excess properties. Speed of propagation of ultrasound waves and densities in pure ILs as a function of temperature and pressure were determined from which several other thermodynamic properties such as compressibilities, expansivities and heat capacities, were derived. The quasi-ideality of mixtures of ILs, as judged by the small values of their excess volumes, could have been predicted by the master linear representation of their pure liquid volumes as the size of either the cation or the anion change. Research has been carried out at a broad range of pressures, typically up to 1600 bar, sometimes inside the metastable liquid region. The current study focuses on [C(n)mim][PF6], [C(n)mim][NTf2], and [C(n)mim][BF4] where n is usually 4, but generally 2 <n <10
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
- …
