The ancient alchemists sought to transform base metals, like lead, into precious gold. Now a new process developed at the University of Illinois at Chicago suggests that base metals may be worth more than their weight in gold -- as catalysts in the manufacture of countless products made from petroleum-based raw materials.
The process is described online in the Journal of the American Chemical Society. Pharmaceuticals, electronic components, plastics and fuels are just some of the goods based on petroleum, a hydrocarbon molecule. But to use petroleum, the chemical bonds between its hydrogen and carbon atoms must first be broken so that other elements can be added. Breaking those bonds -- other than by burning -- is a challenge to chemists.
"These carbon-hydrogen bonds are inert, and a catalyst is required to facilitate the chemical reactions that cause the bonds to break," says Neal Mankad,
UIC assistant professor of chemistry, who developed the process with his graduate student Thomas Mazzacano. Most catalysts used currently are scarce and expensive "noble" metals, such as platinum, palladium and iridium. They are also toxic, and difficult to completely remove from pharmaceuticals and other products for human consumption.
"These metals are used for one reason -- because they work really well, and there are few alternatives," Mankad said. "Finding safer and cheaper substitutes for these noble-metal catalysts is a major goal of modern chemistry."
Mankad has developed a way to use copper and iron together to replace the extremely rare metal catalyst iridium, which is used in a chemical process called borylation. Adding a boron atom to carbon is the first step in the synthesis of many products, from chemotherapy drugs to adhesives and polymers.
"Iridium is literally the least abundant element on the periodic table," Mankad said. "In fact, much of it comes from meteorites."
In the borylation reaction, iridium takes the two electro
|Contact: Sharon Parmet|
University of Illinois at Chicago