Part of the reason the compounds are so useful is the highly unreactive nature of the carbon-fluorine bond, but this also makes it very hard to convert them into other chemicals for safe disposal or recycling into other products.
Now Oleg Ozerov and Christos Douvris of Brandeis University, US, have developed a process that uses a catalyst to convert carbon-fluorine bonds in trifluoromethyl and nonafluorobutyl groups to carbon-hydrogen bonds – a reaction known as hydrodefluorination. The process works under mild conditions and is the first example of efficient catalytic hydrodefluorination of perfluoroalkyl groups at ambient temperature.
“Activation of carbon-fluorine bonds is one of the great unsolved challenges of chemistry,” Ozerov told environmentalresearchweb. “Most of the previous work in this area was not successful with heavily fluorinated alkanes. We conceived our approach to address this deficiency.”
The researchers used a silylium-carborane as the catalyst, which enabled defluorination of the perfluoroalkyl groups by a silane compound. What’s more, the catalyst remained active for many reaction cycles.
“In terms of environmental relevance, it is possible that this research opens the door to potential new technologies for remediation of fluorinated environmental pollutants,” said Ozerov. “I should stress that the research as is right now is not practical, but the Science paper is a proof of principle, not an attempt to demonstrate actual practicality.”
While the team has shown that it can hydrodefluorinate hydrofluorocarbons, perfluorocarbons (PFCs), which contain no carbon-hydrogen bonds but only carbon-fluorine bonds, remain a challenge. “Our future work will aim at improvements in the process to enable us to tackle PFCs,” said Ozerov.
The researchers reported their work in Science.