Making Chemistry greener with solvent alternatives

Chlorinated solvents that are used in everything from cleaning agents to anaesthetic could often be replaced by greener, less toxic alternatives according to a new review.

Scientists from the University of Nottingham’s school of Chemistry, based at the GSK Carbon Neutral Laboratory for Sustainable Chemistry, have published a review in Chemical Reviews summarising why chlorinated solvents found such prominence in chemical laboratories in the first place, the inherent risks associated with their use, and most importantly the alternatives that are available.

To help the scientific community move towards these alternatives the scientists have also created a free resource showing the alternatives to solvents to help improve the sustainability of chemical processes.

Chlorinated solvents are used widely in chemistry laboratories and the wider chemical and pharmaceutical industry. Though they are extremely useful as solvents, degreasers, cleaning agents and even as anaesthetics, the environmental health and safety hazards associated with their use are multiple. Many of the commonly used chlorinated solvents are toxic, carcinogenic and harmful to the environment.

A number of these solvents are even banned from widespread use due to their ozone depleting potential. Most chemical processes in the pharmaceutical industry require large volumes of solvent, up to 90% of the entire mass of the process can be compromised of solvent. This reliance on chlorinated solvents can introduce a significant amount of hazardous waste and dangers to workers and the environment.

Our paper recommends that synthetic chemistry as a field can transition away from a heavy reliance on unsustainable, harmful chlorinated solvents. For almost every example of a widely used process in organic and medicinal chemistry, that regularly utilises a chlorinated solvent, there are now examples of far safer more sustainable alternatives.

As part of the EPSRC Prosperity Partnership project between GSK, University of Nottingham and University of Strathclyde, the researchers have worked closely with the pharmaceutical industry to create a printable 4-page resource that’s free to use that highlights the top 25 most common/popular organic and medicinal chemistry reactions. For each reaction, a safer and more sustainable solvent in which to conduct them is proposed, supported by literature precedent.

Andrew continues: “One of the major hurdles in convincing chemists to migrate from chlorinated solvents is literature precedent and old habits dying hard. The reliance on chlorinated solvents has also become a self-reinforcing problem. When a chemist checks the literature, they find only chlorinated solvents have ever been used for the reaction they are interested in, so they naturally use a chlorinated solvent and add to the problem by publishing their own work using unsustainable conditions. This paper seeks to address this problem and break the cycle by providing real examples, case studies and visual guides from successful solvent replacements projects over the past 10-15 years.We hope that this paper will become the corner stone/gold standard for any laboratory wishing to begin implementing more sustainable solvent practices.”

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