Turning harmful greenhouse gas into drug reagents
One man’s trash is another man’s treasure, and a team of chemists at University of Southern California (USC) managed to utilize an ozone-destroying greenhouse gas which previously had little practical use. They managed to transform fluoroform – a common byproduct in Teflon manufacture – into reagents that could be used in structurally elaborate pharmaceuticals, agrochemicals, and materials.
Companies which produce Teflon have huge tanks of production byproduct and are unable to simply release it due to the potential damage to the environment. Fluoroform is one such byproducts and it has an estimated global warming potential 11,700 times higher than carbon dioxide. G. K Surya Prakash, professor of chemistry at the USC Dornsife College of Letters, Arts and Sciences and director of the USC Loker Hydrocarbon Research Institute, has spent decades working with fluorine reagents and he saw the tanks of fluoroform as an untapped opportunity.
About a quarter of drugs on the market today contain at least one fluorine atom. It can be found in a wide variety of drugs, ranging from a widely used cancer treatment 5-Fluorouracil to Prozac or Celebrex. While fluorine is about the same size as a tiny hydrogen atom — so similar that living cells cannot tell the two elements apart — it also has extremely strong attraction for electrons (it is electronegative). Its electronegative property makes carbon-fluorine chemical bonds quite strong, thus improving the bioavailability of drugs made with fluorine.
Prakash led a team that included longtime colleague George Olah, Distinguished Professor of Chemistry at USC Dornsife, and research associates Parag Jog and Patrice Batamack. After many years of trial-and-error expermetns, the team led by Prakash pinned down the precise conditions needed to transform the harmful fluoroform (CF3H) into useful reagents, including the silicon-based Ruppert-Prakash Reagent for efficient CF3 transfer.
They also managed to find another use for fluoroform by combining it with elemental sulfur, thus creating trifluoromethanesulfonic acid – a superacid which is 100 times stronger than sulfuric acid. The methodology developed by USC researchers is also widely applicable to a variety of silicon, boron, as well as carbon-based electrophiles and it could lead to development of new materials.
For more information, read the article published in the journal Science: “Taming of Fluoroform (CF3H): Direct Nucleophilic Trifluoromethylation of Si, B, S and C Centers”.