Use Safer Solvents and Auxiliaries

This principle asks chemists to choose the safest solvent available for each step of a reaction, and to minimise the total amount of solvents and auxiliary substances used overall, since solvents typically make up a large share of the total waste a chemical process generates. Solvents are substances that dissolve solutes to form solutions and so facilitate many reactions, but using toxic solvents affects millions of workers every year and carries knock-on consequences for consumers and the environment. Because many solvents are used in very high volumes and many are themselves volatile organic compounds, their use generates large amounts of waste, air pollution and other health impacts -- finding safer, more efficient alternatives, or removing solvents from a process altogether, is one of the best ways to make that process or product genuinely greener. The chapter's central illustration is replacing volatile halogenated organic solvents such as dichloromethane (CH2Cl2), chloroform (CHCl3) and carbon tetrachloride (CCl4) with green solvent …