Metrics: Summary and Further Reading

Reproduced Content

This page reproduces content from L. Summerton and A. Constandinou, Beyond Mass-based Metrics: Evaluating the Greenness of Your Reaction, in Green and Sustainable Medicinal Chemistry: Methods, Tools and Strategies for the 21st Century Pharmaceutical Industry, L. Summerton, H. F. Sneddon, L. C. Jones and J. H. Clark, Royal Society of Chemistry, Cambridge, UK, 2016, ch. 4, pp. 41-53.

It is copyright to the Royal Society of Chemistry (RSC) and is reproduced here with their express permission. If you wish to reproduce it elsewhere you must obtain similar permission from the RSC.

Metrics will not provide a definitive answer to the question ‘is my reaction green?’ – this is never a straightforward yes or no answer, as there are numerous factors to take into consideration. It should however help to answer probably the most important question, ‘is my reaction greener?’  As with all things, a balance must be struck and a number of considerations should be incorporated into the decision making process.

An approach that encompasses more than mass based metrics has been studied in this module.  This, alongside a greater understanding of the issues surrounding sustainability, and the ability to interpret the metrics results, should provide evidence to suggest where improvements could be made, and where methodologies are performing well.  

Ultimately, the use of metrics bridges the gap between discovery and larger scale/process chemistry by highlighting issues at an earlier stage.

Recommended reading:

S. Abou-Shehada, P. Mampuys, B. U. W. Maes, Clark and L. Summerton, An evaluation of credentials of a multicomponent reaction for the synthesis of isothioureas through the use of a holistic CHEM21 green metrics toolkit, Green Chem., 2016, 19, 249–258.

R. C. McElroy, A. Constantinou, L. C. Jones, L. Summerton and J. H. Clark, Towards a holistic approach to metrics for the 21st century pharmaceutical industry, Green Chem., 2015, 17, 3111-3121.

L. Summerton and A. Constandinou, Beyond Mass-based Metrics: Evaluating the Greenness of Your Reaction, in Green and Sustainable Medicinal Chemistry: Methods, Tools and Strategies for the 21st Century Pharmaceutical Industry, L. Summerton, H. F. Sneddon, L. C. Jones and J. H. Clark, Royal Society of Chemistry, Cambridge, UK, 2016, ch. 4, pp. 41-53.

D. J. C. Constable, A. D. Curzons and V. L. Cunningham, Metrics to ‘green’ chemistry-which are the best?, Green Chem., 2002, 4, 521-527.

C. Jimenez-Gonzalez, D. J. C. Constable and C. S. Ponder, Evaluating the “Greenness” of chemical processes and products in the pharmaceutical industry-a green metrics primer, Chem. Soc. Rev., 2012, 41, 1485-1498.

Returning to the original question

Look at the methods again from the first module (c.f. Why are Metrics important?) now we have provided the assessment using the CHEM21 metrics toolkit at 1st pass.[1]

Would you now change your mind about the greenest option?

There is not necessarily a right or wrong answer.  But this example shows:

  • How it is important to have more information on a reaction than just yield;
  • The need to balance/weigh up the different parameters.
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  1. L. Summerton and A. Constandinou, Beyond Mass-based Metrics: Evaluating the Greenness of Your Reaction, in Green and Sustainable Medicinal Chemistry: Methods, Tools and Strategies for the 21st Century Pharmaceutical Industry, L. Summerton, H. F. Sneddon, L. C. Jones and J. H. Clark, Royal Society of Chemistry, Cambridge, UK, 2016, ch. 4, pp. 41-53.