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Molecules having two different mirror-image forms are described as 'chiral,' and many biological functions, especially of enzymes, depend upon this property - for example, it is common for only one such form of a drug molecule to have the desired effect. The generation of just one of the two forms is called 'asymmetric' synthesis.The project aims to exploit an exciting new concept for selectively introducing oxygenation into organic molecules, using water and electricity as the sole reagents. The project is possible as a result of an unusual collaboration between experts in electrochemistry and in asymmetric catalysis, and uses a very new discovery in the electrochemistry area to drive a recently-developed selective catalytic oxidation system, so obviating the need for a stiocheiometric reagent (other than electricity and water). This has never before been achieved.Electrochemistry plays a key role in a range of industrial sectors, and has repeatedly been identified as a highly promising methodology for the 'greening' of dirty chemical processes. Electricity provides the means to activate electrode surfaces, to catalyse chemical processes, and to replace a host of chemical reagents simply by supplying electrons of appropriate energy in an electrode system. The emulsion system which we propose to use allows any type of substrate to be introduced and reacted efficiently. The reactor will be useful for a wide range of everyday chemical transformations.The proposal aims to combine recently developed electrochemical technology based on boron-doped diamond as electrode material with new asymmetric epoxidation chemistry and 'active oxygen' processes, to achieve a number of important chemical transformations. A novel epoxidation catalyst will be employed free of heavy metals and permitting catalytic enantioselective oxygen transfer to alkenes over a short timescale, in the presence of as little as 0.1 mol% of catalyst. This very low level of catalyst loading is unprecedented for an 'organocatalyst,' containing no metal atoms. The chemistry involved is novel, clean, uses inexpensive reagents, and is amenable to scale up. The catalysts are indefinitely stable at room temperature.In the course of the project, the recently developed epoxidation chemistry will be introduced into a new type of electrochemical reactor. The reactor uses boron-doped diamond electrodes to generate 'active oxygen' in form of peroxides, hydroxyl radicals, and ozone, depending on the reaction conditions. In the three parts of the project, selective/asymmetric epoxidation, hydroxylation, and ozonolysis will be studied.In addition to the bulk scale electrosynthesis work, mechanistic electrochemical investigations will explore the pathway of the epoxidation process, identify reactive intermediates, and allow better ways of conducting the process to be found. For a complex system, such as an emulsion under phase transfer condition and employing interfacial catalysis, many important reaction parameters exist, and the key factors must be identified.Overall, the project aims to provide new clean technology and a new electrochemical reactor for a wide range of important chemical transformations including asymmetric epoxidation, hydroxylation, oxidation, and ozonolysis.
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