Green metrics, assessing reactions

Andraos, J. (2007) On the Use of Green Metrics in the Undergraduate Organic Chemistry Lecture and Laboratory to Assess the Mass Efficiency of Organic Reactions. Journal of Chemical Education, 84, 1004-1010. 

Why is Life Cycle Assessment important 13) How can analytical techniques be used to follow the course of a reaction 14) What is the Toxics Release Inventory 15) What are green metrics Are mass and energy good enough indicators of environmental impact 16)... 

Figure 8.4 Battery of metrics for assessment of the material greenness of synthesis reactions. Left The assessment (and optimization) involves two dimensions that require different metrics. Right Scope and hierarchy of the metrics.

Ribeiro, M. G. T. C. Yunes, S. K Machado, A. A. S. C. Assessing the Greenness of Chemical Reactions in the Laboratory Using Updated Holistic Graphic Metrics based on the Globally Harmonized Systems of Classification and Labeling of Chemicals. J. Chem. Educ. 2014, Pi, 1901-1908. 

The interpretation of the metrics assessment from the toolkit highlights where research is performing well in terms of its greenness and suggests areas where improvements could potentially be made. The toolkit can also be used to assess state-of-the-art reactions/routes to target compounds to provide a benchmark against which to compare results. 

For instance, in the above case of mass metrics, very important to assess the materialization of synthetic reactions to pursue the dematerialization of chemistry, the metrics AE and E-factor were found to be insufficient to account for all aspects of material greenness a decade after their conception, and since then a lot of alternative reductionist metrics have been proposed. This is not unexpected, as the calculation of metrics should be easy... 

Table 8.2 Components of a synthesis reaction captured by the mass metrics of a battery suitable to assess its material greenness."...

Two further points deserve comment. First, in practice, the two types of materialization (reagents vs. auxiliary materials) are not independent, for instance, decreasing the volume of the solvent used as reaction mean, to decrease the E-factor, may affect the yield of the reaction, and change the value of RME. Second, while the evaluation of the atomic greenness involves two metrics, the materialization via auxiliary materials is assessed by one only, the E-factor (or MI), because there is no theoretical upper limit for the amount of matter used in them (for the atomic greenness, the stoichiometric equation defines AE as such a limit). This situation makes difficult the comparison of auxiliary materials responsible for materialization in different reactions and, consequently, of their global materialization, because it is impossible to define a normalized scale for the E-factor (or MI). This is a... 

In more recent activities, the green star is being used in a broader study of the synthesis experiments used in the 1st and 2nd years organic and inorganic laboratories of chemistry BSc courses of Portuguese universities. This study showed that the metric is adequate to evaluate separately the three stages of the synthesis process, the reaction step (with ten corner stars), and the two post-reaction steps, isolation and purification (six corner stars). This assessment of the micro-greenness of the steps shows that the post-reaction... 

---