PROVIDENCE, R.I. [Brown University] A key advance, newly reported by chemists from Brown and Yale Universities, could lead to a cheaper and more sustainable way to make acrylate, an important commodity chemical used to make materials from polyester fabrics to diapers.
Chemical companies churn out billions of tons of acrylate each year, usually by heating propylene, a compound derived from crude oil. "What we're interested in is enhancing both the economics and the sustainability of how acrylate is made," said Wesley Bernskoetter, assistant professor of chemistry at Brown, who led the research. "Right now, everything that goes into making it is from relatively expensive, nonrenewable carbon sources."
Since the 1980s researchers have been looking into the possibility of making acrylate by combining carbon dioxide with a gas called ethylene in the presence of nickel and other metal catalysts. CO2 is essentially free and something the planet currently has in overabundance. Ethylene is cheaper than propylene and can be made from plant biomass.
There has been a persistent obstacle to the approach, however. Instead of forming the acrylate molecule, CO2 and ethylene tend to form a precursor molecule with a five-membered ring made of oxygen, nickel, and three carbon atoms. In order to finish the conversion to acrylate, that ring needs to be cracked open to allow the formation of a carbon-carbon double bond, a process called elimination.
That step had proved elusive. But the research by Bernskoetter and his colleagues, published in the journal Organometallics, shows that a class of chemicals called Lewis acids can easily break open that five-membered ring, allowing the molecule to eliminate and form acrylate.
Lewis acids are basically electron acceptors. In this case, the acid steals away electrons that make up the bond between nickel and oxygen in the ring. That weakens the bond and opens the rin
|Contact: Kevin Stacey|