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Process Mass Intensity Metric

Process Mass Intensity (PMI) is used to benchmark the “greenness” of a process by focusing on the total mass of materials used to produce a given mass of product. PMI accounts for all materials used within a pharmaceutical process, including reactants, reagents, solvents (used in the reaction and purification), and catalysts, and is, therefore, being employed to improve the efficiency of pharmaceutical syntheses by optimizing the use of these resources. [1] It has also helped drive industry focus towards the main areas of process inefficiency, cost, environmental impact and health and safety, allowing for the development of more sustainable and more cost-effective processes.

The ACS GCI PR have developed a PMI Calculator that enables a PMI value to be quickly determined and thus, “greener” manufacturing processes to be obtained.

There has been progression beyond the simple PMI Calculator to a Convergent PMI Calculator and a PMI Prediction Calculator. These employ the same principles as the simple PMI Calculator but offer more advanced PMI Calculations.

Convergent Process Mass Intensity Calculator

This tool works in the same way as the PMI Calculator but allows multiple branches for single step or convergent synthesis.

Process Mass Intensity Prediction Calculator

This calculator was created by the ACS GCI PR, with leadership from Bristol-Myers Squibb, to estimate probable PMI ranges, i.e., it can predict PMI prior to any laboratory evaluation of the chemical route, or at any other stage of a molecule’s development. This, therefore, allows for the assessment and comparison of potential route changes.

Additionally, the Green Chemistry Innovation Scorecard Calculator (iGAL) was established by the IQ Consortium, ACS GCIPR, and academic leaders. It accounts for process mass intensity (PMI) slightly differently, by focusing on waste. It provides a relative process greenness score which allows for comparisons between different processes and their waste reductions. [2] [3]

  1. C. Jimenez-Gonzalez, C. S. Ponder, Q. B. Broxterman and J. B. Manley, Using the Right Green Yardstick: Why Process Mass Intensity Is Used in the Pharmaceutical Industry to Drive More Sustainable Processes, Org. Process Res. Dev. 2011, 15, 4, 912–917
  2. F. Roschangar, J. Li, Y. Zhou, W. Aelterman, A. Borovika, J. Colberg, D. P. Dickson, F. Gallou, J. D. Hayler, S. G. Koenig, M. E. Kopach, B. Kosjek, D. K. Leahy, E. O’Brien, A. G. Smith, M. Henry, J. Cook and R. A. Sheldon, Improved iGAL 2.0 Metric Empowers Pharmaceuticals Scientists to Make Meaningful Contributions to United Nations Sustainable Development Goal 12, ACS Sustainable Chem. Eng. 2022, 10, 16, 5148–5162.
  3. E. R. Monteith, P. Mampuys, L. Summerton, J. H. Clark, B. U. W. Maes and C. R. McElroy. Why we might be misusing process mass intensity (PMI) and a methodology to apply it effectively as a discovery-level metric. Green Chem., 2020, 22, 123-135.