Chemists have finally succeeded in breaking down a famously unalterable molecule – and persistent greenhouse gas – at room temperature.

The molecules, known as fluorocarbons, are found in plastics, clothing and refrigerants. At their heart is a union of carbon and fluorine – a union that, thanks to their atomic configurations, is one of the strongest molecular unions known in nature.

Under standard conditions, fluorocarbons are impervious to acids and bases. They don't give or receive electrons, the very currency of molecular reconfiguration. Breaking them down is possible only at temperatures approaching 2000 degrees Fahrenheit.

In some situations, that stability is a blessing: Teflon is made from fluorocarbons. But so are the hydrofluorocarbon coolants in refrigerators and air conditioners – and when released, those become greenhouse gases that can circulate for thousands of years.

Though now found only in trace amounts in the atmosphere, scientists fear their accumulation.

"They're not the major contributor to global warming, but per molecule they're much more potent than carbon dioxide," said Brandeis University chemist Oleg Ozerov. "They're so stable that, unless we decompose them, they're pretty much here to stay."

In a study published today in Science, Ozerov and fellow Brandeis chemist Christos Douvris discovered a chemical reaction by which fluorocarbons can finally be decomposed.

The process involves trialkylsilium – a powerful acid – and triethylsilylium hexachlorocarborane, a catalyst that speeds the reaction. The acid bonds with a fluoride molecule from the fluorocarbon, in the process emitting a carbon atom. The carbon bonds with the catalyst, emitting a silylium ion that bonds with another fluoride atom.

"It's sort of a shuffle. A merry-go-round," said Robin Perutz, a

University of York chemist who was not involved in the study. "The key is the efficiency of the catalyst. This one goes around for many cycles: you don't need much of it. Previously you could do nothing useful with these molecules at room temperature."

Ozerov cautioned that the process has yet to be scaled to industrial levels.

If that can be done, "it's a good thing," said Dave Hamilton, director of the Sierra Club's Global Warming and Energy Program. "It begins to solve a thorny global warming problem."

Hydrodefluorination of Perfluoroalkyl Groups Using Silylium-Carborane Catalysts [Science] [not yet online]

A Catalytic Foothold for Fluorocarbon Reactions [Science] [not yet online]

*Image: Eric Crowley. These refrigerators are actually old and probably ran on chlorofluorocarbons, or CFCs – a type of fluorocarbon that was outlawed after its ozone layer-eating effects were revealed. Chlorofluorocarbons were replaced with hydrofluorocarbons, which turned out to be greenhouse gases; it's these that Ozerov and Douvris broke down.

*

See Also:

WiSci 2.0: Brandon Keim's Twitter stream and Del.icio.us feed; Wired Science on Facebook.