Reducing solvent use is therefore usually a high priority for chemists working on making their reactions greener, especially when working on an industrial scale.įor example, Pfizer was able to reduce the amount of solvent waste generated in its synthesis of Viagra from 1300 kilograms to just 22 kilograms for every kilogram of Viagra made. This reliance on solvents means that a massive amount of solvent waste is generated during a typical chemical reaction. After the reaction, more solvents are then often used to separate and purify the product from other reaction components and any side-products. Usually, solvents themselves do not react with the reagents but are still necessary in reactions in order to dissolve reagents, mix all reaction components, and control the temperature of the reaction. Solvents are the most common example of auxiliary substances. In the video for Principle #5, we talk about the impact of solvent waste and illustrate it by substituting dichloromethane, a commonly-used solvent, with a safer alternative. This includes any substances that do not directly contribute to the structure of the reaction product but are still necessary for the chemical reaction or process to occur. The 5 th principle of green chemistry promotes the use of Safer Solvents and Auxiliaries. solvents, separation agents, etc.) should be made unnecessary wherever possible and innocuous when used. Safer Solvents and Auxiliaries: The use of auxiliary substances (e.g.
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