Chapter 2: Recyclability of Reagents

Over the past century, the development of new pharmaceutical products in the form of improved drugs has contributed significantly to a breakthrough revolution in medical care, enabling dramatic reductions in hospitalization, suffering and death. However, this achievement has come at a cost because, despite being a fertile ground of innovation, these industries have unfortunately been the major source of waste generation, which has adversely affected human health and the environment. Consequently, pharmaceutical process chemists are now concentrating their efforts and creative energies towards minimizing the environmental impact of their craft with the help of new biosynthetic routes, solvent substitution practices, elimination of hazardous substances and the reuse and recycling of reagents. Strikingly, much success has been accomplished in the redesigning of pharmaceutical processes as evident from the list of industrial companies that have won the US Presidential Green Chemistry Challenge awards. In the present chapter, we provide a comprehensive view to the readers about pharmaceutical wastes (their types and how they enter into the environment), reagents used in process development (solvent, catalyst, packaging materials), process efficiency metrics used for assessing the greenness of a reaction and waste management techniques being adopted across the world. We have also included a few case studies in order to highlight how big pharma companies like Pfizer, Bristol-Myers Squibb, ChemGenes Corporation, Novartis, GlaxoSmithKline and Merck have discovered/come up with efficient reagent recovery and recycling strategies for improving the current synthetic protocols.