2. Atom Economy and Reaction Mass Efficiency

The green metrics atom economy (AE) and reaction mass efficiency (RME) are introduced and discussed. Following literature definitions, examples of reactions appropriate for upper-level undergraduate students are provided to illustrate how the metrics are calculated. In the case of atom economy, important assumptions regarding reactants, solvents and reagents are identified and explained. Several examples of inherently atom-efficient and inefficient reactions are also provided. In terms of reaction mass efficiency, the focus centers on a concise mathematical breakdown of various factors which contribute to changes in RME values in the context of two well-established definitions. A view of RME as a more robust metric that better captures the materials used during a chemical transformation is developed in the context of an undergraduate Suzuki reaction. With numerous academic and industrial examples comparing traditional syntheses with modern catalytic routes, the benefits and limitations of AE and RME are considered. Along with real-world case studies, the useful and effective application of these metrics is explained using several definitions of an ideal chemical reaction as points of reference. Finally, future projections and academic work are briefly outlined in order to highlight the development of these important metrics.