The Growing Impact of Continuous Flow Methods on the Twelve Principles of Green Chemistry

This chapter considers the beneficial combination, and potential impact, of continuous flow methodology with the twelve Principles of Green Chemistry as developed by Anastas. Whilst the application of continuous flow reactions is changing the way medicinal chemists are making and trying to identify lead bioactive compounds, the main impact of flow methods on green chemistry is in process development and manufacture where the volumes of materials produced are far greater. The least wasteful strategy for synthesizing a product is one in which no by-product is formed and the reaction is 100% atom-efficient. A way of reducing the impact of hazardous reagents is through their immediate synthesis and use in further reactions. Flow processes offer potential for avoiding or minimizing solvent, because higher viscosities with more intense mixing, and better energy management can be achieved than in batch. Chemical products should be designed so that at the end of their function they break down into mild degradation products via biodegradation, hydrolysis, or photolysis and do not persist in the environment. Flow processes offer potential advantages for the production of bio-based materials and have been combined with numerous robust catalytic systems and alternative reaction media including supercritical fluids and ionic liquids.