New ligand technology for solving challenging environmental problems

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The long term theme of the proposed research program is to develop chemical transformations which will result in the development of more energy efficient and affordable industrial processes. The goals outlined below involve selected ligand designs for the formation of new complexes with a focus on solving major environmental challenges.***The gold problem: cyanidation is the dominant process for extraction and recovery of gold from low-grade gold ore due to the high leaching efficiency and mature technology of the process. The use of large amounts of sodium cyanide remains controversial and is of great environmental concern, however no viable alternative to cyanide that can be implemented at an industrial scale has been developed. until now. We are developing a gold extraction process using a sulfur-based ligand system applicable to the gold mining industry that we anticipate will (i) completely eliminate use of cyanide and in the process be (ii) faster and cheaper than existing cyanide technology, (iii) be more environmentally friendly and safer and (iv) be simple and easy to implement. Essential to this research will be an investigation into the mechanism of gold extraction so that we can better understand the chemistry taking place and thus further improve on our designs as we revolutionize the gold industry.***The plastic problem: global plastic production is currently exceeding 200 million tonnes per year, the vast majority of which is derived directly from fossil fuels. Conventional polymers such as polyethylene and polypropylene (which alone account for 125 million tonnes of global plastic production) can persist in the environment for over 100 years and accumulate in waste dumps and in oceans. Over 35% of polyethylene (PE) and polypropylene (PP) production goes to product packaging, applications in which the plastics are used on a short term basis and then disposed. The development of biodegradable polymers that can mimic the properties of PE presents the opportunity to produce environmentally friendly alternatives to conventional plastics. Highly promising candidates for PE mimics are polymers obtained from macrolactones. We are developing efficient, single-component catalysts for the ring-opening polymerization of large-ring aliphatic cyclic esters and intend to develop this technology as a viable alternative to polymers derived from fossil fuels. The resulting polymers would mimic the properties of fossil fuel-based plastics but would be biodegradable and be derived from renewable resources.*** *** **