Green Chemistry Metrics - The EcoScale

The EcoScale

The EcoScale is a recently developed metric tool for evaluation of the effectiveness of a synthetic reaction. It is characterized by simplicity and general applicability. Like the yield-based scale, the EcoScale gives a score from 0 to 100, but also takes into account cost, safety, technical set-up, energy and purification aspects. It is obtained by assigning a value of 100 to an ideal reaction defined as "Compound A (substrate) undergoes a reaction with (or in the presence of)inexpensive compound(s) B to give the desired compound C in 100% yield at room temperature with a minimal risk for the operator and a minimal impact on the environment", and then subtracting penalty points for non-ideal conditions. These penalty points take into account both the advantages and disadvantages of specific reagents, set-ups and technologies. By calculating the EcoScale, a quick assessment of the "greenness" of reaction protocols is obtained, and the areas that need further attention are clearly indicated, which finally can drive improvement of reaction conditions.