No description available.

No description available.

No description available.

No description available.

With the ever increasing limitations being placed by regulations, cost and social acceptance on the processes that chemists can use to satisfy society's demands, the need to improve the control that can be exerted on reactivity and to lessen the impact of our industry has never been so prescient. As a solvent, CO2 exhibits a unique set of properties that potentially open up areas of process control that are otherwise unavailable. Due to the infancy of this technology, the impact of using CO2 in conjunction with many otherwise typical chemical processes remains relatively unexplored. Herein we present the results of utilising CO2 as a solvent for the bromination of a number of substituted benzenes and compare them to the analogous reaction in conventional solvents. The influence of CO2 on these reactions in terms of changes to regioselectivity and variation of the reaction pathways is explained with reference to Hammett δ electronic effects and the relative solubilities of the different species. The scope of the palladium carbene catalyst PEPPSI-IPr is broadened to include Heck reactions, a protocol it has shown little suitability for up to now, via an apparent in situ reduction of the pre-catalytic species by aniline. A limited amount of evidence is provided that may indicate the reactions are being catalysed by palladium nanoparticles. Finally, high pressure CO2 is explored as an antisolvent in a study designed to gather the preliminary data required to design and construct an apparatus to allow the continuous flow processing of post-reaction crude mixtures in a manner that potentially could significantly reduce the amount of waste solvent generated from chemical processing. The research presented here offers new insight into the potential of CO2 as a solvent both for reactions and for reaction processing. Additionally, the scope of a catalytic process has been expanded.

Several Quartz Crystal Microbalance (QCM) measurement techniques in conjunction with a series of calix[4]resorcinarene sensing membranes have been successfully exploited for the detection of volatile organic solvents at vapour concentrations below their lower explosive level. The impedance analysis technique involves the measurement of the electrical properties of the QCM around the resonant frequencies of crystal. Subsequent fitting of the measured spectra to an equivalent circuit allows parameters directly related to mass loading and the mechanical properties (viscosity) of the film to be obtained. An experimental setup which allows the real time in situ extraction of these parameters has been developed. It has been shown that unique changes in mass loading and the films viscoelastic properties caused by the adsorption of target vapours into a calix[4]resorcinarene C15H31 sensing membrane can be detected. In some cases this facilitates both the detection and discrimination of target vapours using a single QCM sensing element. The changes in the films mechanical properties are believed to be caused by capillary condensation of vapours at values below saturated vapour pressure inside the nano-porous calix[4]resorcinarene film matrix. The work is extended by the use of the sensor array technique. In the first instance frequency only measurements are used. Four QCM have been coated with calix[4]resorcinarene compounds with different hydrocarbon chain lengths and exposed to range of organic vapours. The variation in chain length produces selectivity between the sensing membranes, and leads to the classification of all the tested organic vapours using a feed forward multilayer Artificial Neural Network. The trained network successfully classified over 98% of the test data. The additional measurement of film dissipation using impedance analysis/QCMD shows interesting phenomena. An unexpected increase in mechanical stiffness of the film is observed for small chain length C[4]RA compounds (CH3) on vapour sorption. A speculative model has been proposed relating the chain length and effective cavity size to the observed phenomena. An alternative low cost multi parameter measurement set up has also been developed using the QCMD principle. The crystal is driven from an external oscillatory source and subsequently disconnected. The resonant frequency and dissipation factor can be extracted from the decaying sinusoid signal. This approach eliminates the need for expensive network analysers. An additional multiplexing circuit has been combined with the QCMD technique and allows both the frequency and dissipation factor of several crystals to be measured in pseudo real time. This makes the system ideally suited for multi parameter array measurements. The basis for a discriminative explosive vapour sensor based on calix[4]resorcinarene membranes has been investigated and promising results for future development have been obtained. The exact adsorption mechanisms are however complex and althoughspeculative models have been proposed, further research is suggested to fully characterize the complete adsorption process and the mechanical changes taking place within the film.

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Le bouleversement du monde des solvants classiques, résultant de la récente prise de conscience des risques environnementaux et sanitaires liés à leur utilisation, a conduit au développement de nouveaux solvants présentant un meilleur profil HSE et dérivés de la biomasse végétale : les agro-solvants. Ces solvants alternatifs ont été recensés, modélisés et comparés aux solvants organiques classiques dans un panorama purement théorique établi grâce à l'approche COSMO-RS. Cet outil permet non seulement d'aider à la substitution de solvants indésirables mais aussi de souligner les besoins de nouvelles structures. Une démarche in silico de conception raisonnée d'agro-solvants, via le développement d'un logiciel de synthèse automatique, GRASS, a ainsi été mise en place et permet de générer virtuellement des produits de commodités à partir d'agro-synthons abondants (glycérol, acide itaconique, isosorbide, etc.) et de transformations chimiques pertinentes industriellement. Les structures générées sont ensuite triées via des modèles de prédiction de propriétés physico-chimiques afin de sélectionner les mieux adaptés pour une application donnée. Des agro-solvants dérivés du glycérol et de l'isosorbide (éthers, esters, acétals) ont été sélectionnés, synthétisés puis évalués expérimentalement en considérant leurs propriétés physico-chimiques (Tfus, Téb, d, η, stabilités à l'hydrolyse et à l'oxydation), leurs capacités de solubilisation de deux pesticides cibles et leurs propriétés hydrotropes. Ces mesures expérimentales ont ensuite été confrontées à différents modèles de prédiction. / Many of the traditional organic solvents (halogenated compounds, aromatics, glycols ethers) are banned or about to be, as a result of the recent awareness of the environmental and health risks associated with their use. There is therefore an urgent need to find alternatives with good ESH (Environment, Safety and Health) profiles, preferably coming from renewable feedstock: the so-called biosolvents. In this work, these alternative solvents have been listed, modeled, and compared to classical organic ones to give a purely predictive landscape obtained thanks to the COSMO-RS approach. This tool can be used to help in finding substitution solutions and also highlights the needs for new biosolvents. A Computer-Assisted Organic Synthesis program, named GRASS, has been developed to help in the rational design of biosolvents from a bio-based building block (glycerol, itaconic acid, isosorbide, etc.) through industrially-relevant chemical transformations. Then, all the virtual derivatives generated have been sorted out thanks to property prediction models in order to select the most relevant ones. Biosolvents coming from glycerol and isosorbide (ethers, esters, acetals) have been selected, synthesized and experimentally evaluated as solvents considering their physico-chemical properties (m.p., b.p., d, η, stabilities to hydrolysis and to oxidation), their capacities to solubilise two agrochemicals, and their hydrotropic properties. These experimental data have then been compared to various prediction models.