Chemistry, by its very nature, involves the use of chemicals that can be harmful, toxic and potentially damaging to the environment, which means that drug discovery currently has a large and expensive environmental footprint. However, all is not lost. With a few small steps it is possible to make a big change to the impact that drug discovery has on our world. Let’s look at ways we can reduce the environmental impact of chemical processing and flash chromatography. This involves using green chemistry applications in the purification workflow to find a solution that reduces chemical waste to make it good for both the chemist and the environment.
Solving the solvent problem
A key factor in making the synthetic workflow greener is reducing the environment impact of chromatographic purifications, which often involve the use of large volumes of solvent. For example, flash chromatographic purification traditionally enables the purification of up to grams of material, employing solvents such as hexane and ethyl acetate (although dichloromethane and methanol are also common) as the mobile phase.
Flow rates vary with flash column size but tend to be around 10–100 mL/min, with run times of on average 5–20 minutes that consume liters of solvent. Preparative HPLC involves lower flow rates but the lower loading capacity of the columns means that more runs are needed, again using liters of solvent. Added to that, the large quantities of solvent employed in compound purification must be purchased and stored, manipulated in the laboratory, removed from the final compound by evaporation, and handled by safe and responsible waste disposal to minimize environmental impact.
Going green can reduce costs at many levels
Recent changes in environmental regulation reflect a realization that chemistry can and should be greener. For the chemist, using large quantities of hazardous solvents involves other costs apart from the financial ones – there is also a societal pressure to be more environmentally friendly, and the handling of large quantities of solvent can raise safety concerns. Reducing the environmental impact of synthetic chemistry means being kinder to the environment, and leaving less of a footprint on the world for future generations. Using green solvents and processes that reduce environmental waste and waste disposal concerns go a long way to achieving this.
Added efficiency is a spinoff
Reducing the environmental impact of laboratory work not only reduces costs it often leads to ways of working smarter – with benefits such as quicker workflows, safer processes and more efficient green chemistry. Just because ‘you’ve always done it this way’, doesn’t mean it is the best way moving forward. As an awareness of the environment grows, chemists – along with every responsible global citizen – are looking for ways to become greener and to do their work with a better consideration of all the costs, not just those that are monetary.
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How to reduce your environmental impact
In the next article we will discuss approaches to reducing the environmental impact of the purification component of the small molecule synthetic pathway. We’ll show you that with a few key choices in design and with a little smart thinking, you can vastly reduce the environmental impact of your purifications.