Solvents

Telescoping

To reduce volumes of solvent used, one simple suggestion is to look at the number and types of solvents used in a synthetic pathway to a target molecule. In a synthetic process, it is fairly typical that a number of different solvents are used – this causes additional burden (e.g. removing solvent at the end of each step).  Counting the number of solvent swaps may identify opportunities where steps could be carried out in succession using the same solvent, without the need to isolate the product (telescoping reactions).[1][2]

Within the pharmaceutical industry there can be regulatory issues associated with telescoping due to the need to isolate intermediates in order to demonstrate control.

To study this area in more depth, see Telescoping

  1. G. Assaf, G. Checksfield, D. Critcher, P. J. Dunn, S. Field, L. J. Harris, R. M. Howard, G. Scotney, A. Scott, S. Mathew, G. M. H. Walker and A. Wilder, The use of environmental metrics to evaluate green chemistry improvements to the synthesis of (S,S)-reboxetine succinate, Green Chem., 2012, 14, 123-129.
  2. 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.