Solvents

Introduction

Solvents are liquids capable of dissolving or dispersing other substances. They are used in very high volumes in industry. Cradle-to-gate life cycle studies have shown that solvents are the major contributor to the lifecycle impacts of active pharmaceutical ingredient (API) synthesis.[1][2] From a green chemistry point of view, solvents therefore become an area where significant impact can be achieved through the choice and volumes of solvent used (with or without recycling).

Before looking at solvent replacement strategies, we first need to consider why we use solvents and what factors must be considered when selecting a solvent. Insights into how we choose the right solvent for a reaction or purification can be found in Solvent Guides. It is also useful to consider trends in the use of different solvent types, as well as to identify the types of solvent that are being targeted for substitution through, for example, legislative or other measures. These points will be explored in more detail in this module.

Learning Objectives

By the end of this module, you should:

• Understand why we use solvents;
• Be aware of issues surrounding the use of solvents;
• Be able to identify solvents of concern;
• List considerations for choosing a green solvent;
• List types of alternative solvents
• Know where to find information regarding the selection of green solvents.