Chemical Processing with Ionic Liquids and Carbon Dioxide: Combining Reactions and Separations Using Environmentally Benign Solvents

A new and general type of process for the chemical industry is presented using ionic liquids and supercritical carbon dioxide as combined reaction and separation media. In this process, the carbon dioxide pressure controls the miscibility of reactants, products, catalyst and ionic liquid, enabling fast atom-efficient reactions in a homogenous phase as well as instantaneous product recovery in a biphasic system. High reaction and separation rates can be achieved compared with the conventional fully biphasic alternative. Experimental and theoretical methods are used to find the operating conditions of the new approach. When the ionic liquid/carbon dioxide process is applied to the production of 1600 ton/year Levodopa, a medicine against Parkinsonian disease, the energy consumption is reduced with 20,000 GJ per year and the waste generation is reduced with 4800 ton of methanol per year and 480 kg catalyst per year, resulting in a decrease in total operational costs of 11.3 million euros per year.