Fluoroform plagues producers of polytetrafluoroethylene, polyvinylidene fluoride, refrigerants and other fluorinated products. The compound, which also is called trifluoromethane, CF3H, and HFC-23, is a large-volume byproduct that poses significant disposal issues. It is a stable greenhouse gas with a global warming potential estimated to be about 11,700 times greater than that of carbon dioxide, note researchers at the University of Southern California (USC), Los Angeles. So, chemical makers can't release it and many store sizable quantities of the material. G. K. Surya Prakash (Figure 1), a professor of chemistry at the university and director of the USC Loker Hydrocarbon Research Institute, saw the fluoroform as an untapped resource. He led a team of researchers that now has developed a way to use CF3H to create valuable chemicals.
After years of trial-and-error tests, the team achieved direct trifluoromethylation of silicon, boron, sulfur and carbon using close to stoichiometric amounts of CF3H in common nonpolar solvents such as tetrahydrofuran/ether or toluene and a base. "The developed chemistry has great potential for the preparation of value-added fluorocarbon products for the chemical and pharmaceutical industries from a waste greenhouse gas," believes Prakash. More details on the method, which is being patented, appear in a recent article in Science.
Now, efforts are underway to optimize reaction conditions for higher yields, particularly for the preparation of trifluoromethanesulfonic acid, a widely used superacid catalyst in fine chemicals manufacture, says Prakash. The efforts should take from six months to a year.
The fluoroform-based synthesis approach also should attract interest for producing trifluoromethylated silanes, especially Ruppert-Prakash Reagent, which pharmaceutical makers use, he adds.
Finding an inexpensive base remains a key challenge, Prakash notes.
He envisions the technology will be made available to industry via nonexclusive licenses to produce particular classes of products.