Suchergebnisse

Green Chemistry is a vitally important subject area in a world where being as green and environmentally sound as possible is no longer a luxury but a necessity. Its applications include the design of chemical products and processes that help to reduce or eliminate the use and generation of hazardous substances. Supercritical Fluids (SCFs) and Gas-Expanded Liquids (GXLs) are of great interest in green chemistry becauser either they are nontoxic and non-polluting solvents (like carbon dioxide or water) or they help one to avoid harmful intermediates through new processing routes. This book exa

Abstract Driven by legislation and evolving attitudes towards environmental issues, establishing green solvents for extractions, separations, formulations and reaction chemistry has become an increasingly important area of research. Several general purpose solvent selection guides have now been published with the aim to reduce use of the most hazardous solvents. This review serves the purpose of explaining the role of these guides, highlighting their similarities and differences. How they can be used most effectively to enhance the greenness of chemical processes, particularly in laboratory organic synthesis and the pharmaceutical industry, is addressed in detail. Graphical abstract This review assesses the advances made in green solvent selection using tabular guides and related tools.

Despite used for half a century as host for salt-polymer complexes, PEO is still not a fossil and due to its availability, remains regularly used as a reference in solvent-free polymer electrolytes and related electrochemical cells. Often qualified as macromolecular solvent or immobile solvent, its drawbacks (crystallinity, mechanical strength) are well identified. On the other hand, its electrolyte conductivity maxima are considered as the best possible in absence of molecular solvents or ionic liquids. The comparison of PEO/LiTFSI based on raw PEO and ultrafiltrated one, shows unambiguously the impact of unentangled oligomers not only on ionic transport but also on mechanical behavior. Conductivity, cationic transference numbers and storage modulus data go in the same direction and the cationic conductivity (O/Li = 30) is divided by 2, following PEO purification. ; Jean-Yves Sanchez acknowledges the CONEX Programme, funding received from Universidad Carlos III de Madrid, the European Union's Seventh Framework Programme for research, technological development and demonstration (Grant agreement nº 600371), Spanish Ministry of Economy and Competitiveness (COFUND2013-40258) and Banco Santander. Amadou Thiam acknowledges ANR for his fellowship. Yannick Molméret acknowledges KICINNO Energy for the granting of his post-doc fellowship, in the frame of the project PENLiB coordinated by Prof. Jean-Yves Sanchez.

Driven by legislation and evolving attitudes towards environmental issues, establishing green solvents for extractions, separations, formulations and reaction chemistry has become an increasingly important area of research. Several general purpose solvent selection guides have now been published with the aim to reduce use of the most hazardous solvents. This review serves the purpose of explaining the role of these guides, highlighting their similarities and differences. How they can be used most effectively to enhance the greenness of chemical processes, particularly in laboratory organic synthesis and the pharmaceutical industry, is addressed in detail.

Sustainable development is one of the major concerns of society and of the scientific community presently. These concerns have led to new legislation by the European Union and United Nations focusing on the development of sustainable processes, mostly using greener solvents and renewable feedstocks as well as the implementation of a circular economy. In this sense, it is predicted that the share of bio-based chemicals will exponentially increase in the coming years through the valorization of biomass resources. Moreover, waste management is also a crucial point to achieve Circular Economy. Biomass represents thus a promising source for chemicals and materials. Nonetheless, the use of this feedstock must be carefully planned to be sustainable. To achieve a sustainable exploitation of biomass the use of biorefineries is key. Biorefineries are integrated systems of sustainable technologies for the comprehensive utilization and exploitation of biological raw materials. From the various types of available biomass, lignocellulosic feedstocks present the highest abundance with large quantities of the feedstock being wasted in pulp and paper manufacture and agro-based processes. This feedstock is however very complex, being composed of three main fractions: cellulose, hemicelluloses and lignin. The first two fractions are polysaccharides which can be used to produce new and innovative materials, chemicals and biofuels. Even so, there is a need for more efficient and sustainable use of these biomass fractions. Having these issues in mind, the main aim of this thesis is to explore the valorization of polysaccharides using alternative solvents, such as deep eutectic solvents (DES). The major fraction of the work was focused on the valorization of xylans which compose the majority of hemicelluloses fraction in lignocellulosic biomass. The initial work focused on the dissolution and extraction of these polysaccharides. In this study, the DES [Ch]Cl:Urea was able to solubilize a maximum of 328.23 g/L of xylans using 66.7 wt.% ...