Toxic solvents remain widely used in chemical synthesis
An analysis of 40 years of patent data finds little progress towards safer alternatives.
Researchers at Ghent University, Belgium, and the University of York, UK, analysed 1.3 million chemical reactions, looking separately at solvents used during reactions and those used for work-up, purification and analysis.
The study, The Stubborn Persistence of Toxic Solvents in Chemical Synthesis, found no overall reduction in the proportion of hazardous solvents used as reaction media.
Use of dichloromethane has increased, while growing consumption of trifluoroacetic acid raises concerns about per- and polyfluoroalkyl substances (PFAS).
The researchers say that restrictions on individual solvents have often led to them being replaced with other hazardous substances as opposed to greener alternatives.
The study, published in Angewandte Chemie International Edition, also looked at which types of chemical reactions rely most heavily on toxic solvents, helping to identify where changes could have the biggest impact.
The authors warn that AI tools trained on historical reaction data could reinforce these practices by recommending solvents based on past use rather than sustainability.
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