New patent survey shows chemists still rely heavily on dangerous solvents despite green efforts

Chemists are still using dangerous and carbon-intensive liquids in laboratories much more often than eco-friendly ones, a new study reveals. An analysis of 1.3 million chemical reactions listed in patents over four decades shows that hazardous solvents were used in about 60% of reactions in 1976, but that share rose to above 70% by 2016. Solvents are workhorse liquids used to dissolve chemical substances, and also to extract and purify reaction products. Almost all of them come from oil or natural gas, giving them a large environmental footprint, while some types like dichloromethane carry health or safety risks. The findings were published this month in Angewandte Chemie by Helen Sneddon, a sustainable-chemistry researcher at the University of York, and Maarten Dobbelaere, an AI researcher at the Swiss Federal Institute of Technology in Lausanne. They used an AI-based system named Rxn-INSIGHT to track solvent use across more than 500 different types of chemical reaction within a US Patent and Trademark Office database. Sneddon expressed disappointment at the trend, while Bruce Lipshutz, an organic chemist at the University of California, Santa Barbara, stated that the findings show an urgent need to move away from petrochemical-based solvents. The survey also found that when government rules restrict a toxic solvent, chemists tend to switch to another hazardous liquid instead of a greener option. The analysis noted a rise in the use of trifluoroacetic acid, which is key for making popular peptide drugs and is classified by some definitions as a permanent chemical belonging to the PFAS group found in waterways and living creatures. David Leahy, chair of the advisory board to the American Chemical Society's Green Chemistry Institute, pointed out that early-stage drug discovery researchers aim to make many molecules quickly and face almost zero incentive to use environmentally friendly conditions. However, the study's database ends in 2016, does not measure the actual quantities of solvents used, and mostly records early-stage research rather than scaled-up manufacturing.