502c Designing Green Processes: Phase Behaviour of Ionic Liquid - Carbon Dioxide Based Systems

Eliane Kühne1, Cor J. Peters1, and Geert-Jan Witkamp2. (1) Delft University of Technology, Faculty of Applied Sciences, DelftChemTech (PCMT), Julianalaan 136, Delft, ZH 2628 BL, The Netherlands, (2) Delft University of Technology, Faculty of Design, Engineering and Production, Laboratory for Process Equipment, Leeghwaterstraat 44, Delft, ZH 2628 CA, The Netherlands

Nowadays, industry is facing a substantial challenge to modify its processes to cleaner, environmentally friendly ones. This concerns mainly pharmaceutical companies, which processes consist of several steps, involving large amounts of volatile organic solvents (VOS's) and releasing undesirable waste.

Processes based on ionic liquids and carbon dioxide are emerging as a solution for this problem, mainly for the efficient replacement of VOS's. Additionally, when ionic liquids are combined with carbon dioxide, a remarkable switch in the miscibility of the system is observed. Therefore, when ionic liquids are used as reaction medium, it is possible to apply carbon dioxide pressure in order to perform reactions in one phase, and further extraction of the product by supercritical CO2 from the heterogeneous system.

This novel approach offers attractive advantages, especially to the pharmaceutical industry. Among others, processes can be carried out with no solvent loss, recycling of the ionic liquid and carbon dioxide is possible, and the product is obtained with extremely high purity.

In order to design an efficient process, knowledge on the phase diagrams of the system under consideration is of crucial importance. After identifying the location of the homogeneous and heterogeneous regions, pressure and temperature can be selected to optimize reactions and extractions.

This concept is being studied for two hydrogenation reactions: the first involving acetophenone giving 1-phenylethanol, and the second for a step reaction in the synthesis of s-naproxen, an anti-inflammatory drug. In this contribution we present the phase behaviour of ternary systems [Bmim][BF4] (1-butyl-3-methylimidazolium tetrafluoroborate), carbon dioxide and a solute, i.e., each one of the compounds from the reactions mentioned above. Based on our data, it is possible to select operational conditions to perform the reaction and extraction of the product, analysing this novel concept.