Evaluating the greenness of alternative reaction media

Abstract

The solvent performances and ecological (dis)advantages of different solvent systems for the Diels–Alder reaction of cyclopentadiene and methyl acrylate were investigated. Promising solvent alternatives, especially [C₆MIM][BF₄](1-hexyl-3-methylimidazolium tetrafluoroborate), citric acid/N,N′-dimethyl urea as well as a solvent-free alternative were compared to the conventional solvent systems methanol, cyclohexane, acetone and methanol/water. By means of the ECO (Ecological and Economic Optimisation) method these solvent alternatives were evaluated already during an R&D (Research and Development) stage in a holistic approach. This method is a screening tool that employs a Simplified Life Cycle Assessment (SLCA) approach in combination with an optimisation procedure. All life cycle stages from the production of reactants, solvents etc., synthesis and workup, recycling and disposal are considered within this methodology. With the help of the ECO method, some significant environmental issues depending on the solvent selection are compared in order to make a contribution to the assessment of the greenness of chemical processes and products during R&D.