Mirror, mirror on the wall, which is the greenest of them all? A critical comparison of chemo- and biocatalytic oxyfunctionalisation reactions

Abstract

This review article critically compares two widely used types of catalysis, chemo- and biocatalysis, and provides insights on their greenness according to specified parameters. A comparative analysis of the environmental impact of chemo- and biocatalytic oxyfunctionalisation reactions based on published experimental data reveals that both methods produce comparable amounts of waste, with the majority stemming from the solvent used. However, it is emphasised that the synthesis of the catalysts themselves, including biocatalysts, should also be considered when assessing their environmental impact. The review underscores the complexity of assessing the environmental impact of catalytic oxyfunctionalisation reactions. The article also discusses the relationship between solvent properties and the energy demands for chemical transformations and downstream processing, underlining that the choice of solvent can significantly influence the environmental impact of a catalytic process. Additionally, the review highlights the importance of considering the recyclability of reagents and the secondary CO₂ emissions caused by the energy requirements of the reaction when evaluating the environmental impact of a catalytic process. Each chemo- and biocatalysis produce a certain environmental impact, the greenness of either method is dependent on several factors, including the type of waste generated, the recyclability of reagents, and secondary CO₂ emissions. This review therefore recommends using consistent metrics and a comprehensive life cycle assessment approach to evaluate this environmental impact, and highlights the importance of considering the synthesis of the catalysts themselves.