Greenness of chemical reactions – limitations of mass metrics

Abstract

The influence of reaction conditions (yield, excess of stoichiometric reagent, molecular weights of reagents, and mass of auxiliary materials and solvents) on the values of several green chemistry mass metrics (E-factor, mass intensity, atom utilization, relative mass efficiency, and element efficiency), for reactions with 1:1 and 1:3 stoichiometries, has been analyzed, as well as relationships between the metrics. The theoretical behavior of these, when visualized by three-dimensional graphic representations, e.g. surfaces of metric 0 f(yield, excess), together with the experimental values, facilitates the management of its improvement Á changes in conditions in successive experiments should follow the directions shown by the graph. The study shows that there are practical limitations to the greenness increase due to the complex nature of the chemistry but confirms that it is worthwhile to pay more attention to the effort of obtaining quantitative details of the laboratory syntheses to acquire information to assess greenness.

How Efficient Is My (Medicinal) Chemistry?

“…There are numerous articles, reviews, and books dealing with green chemistry. A short and arbitrary selection can be found in references [ 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 ].…”

Planetary metrics for the absolute environmental sustainability assessment of chemicals

“… 5 However, these single-factor metrics started showing practical limitations evaluating the greenness of a chemical due to the continuous advances in the field and the inherently complex nature of the chemical routes. 6 Accordingly, the current trend is to replace single-factor metrics by multi-factor indicators to provide evidence of a significant advance in green chemistry, which should be applied in any experimental work. 7 Among the indicators available, those based on life cycle assessment (LCA) have been recommended and are gaining broad interest in the community.…”

Aiming for a standardized protocol for preparing a process green synthesis report and for ranking multiple synthesis plans to a common target product

“…However, they completely neglect other factors that are equally important in tracking and ultimately ranking continued improvements in process synthesis design such as environmental and occupational impact, and energy consumption. Limitations of massmetrics-only analysis in decision-making and ranking have been discussed previously [16]. Over the years more holistic analyses of synthesis plans to pharmaceutical targets have addressed these deficits by including environmental and safety-hazard assessments such as Edwards-Lawrence algorithm [17], EATOS [18][19][20], EcoScale [21], Green Star [22], and FLASC [23].…”