It is hard to find a place on Earth that is not affected by palladium . The silver-white metal is a key ingredient in the catalytic converters of 1.4 billion cars worldwide, which spew palladium pellets into the atmosphere. Palladium pollution is exacerbated by mining, etc. Traces of palladium have appeared in some of the most remote places on Earth, from Antarctica to the top of the Greenland ice sheet. In fact, palladium is also indispensable for pharmaceuticals. That’s because catalysts with palladium atoms at their core have an unparalleled ability to help the carbon-carbon bonds hold together. This chemical reaction is key to building organic molecules, especially those used as drugs. “Every drug we make has a palladium-catalyzed step at some point,” says Per-Ola Norrby, a drug researcher at AstraZeneca, a pharmaceutical giant in Gothenburg, Sweden. Palladium’s catalyzed reactions are so valuable that in 2010, The discoverer of this reaction won a Nobel Prize. Despite palladium’s many uses, chemists are trying to get rid of it. The metal is more expensive than gold, and palladium-containing molecules are highly toxic to humans and wildlife. Chemical manufacturers must separate all palladium from their products and dispose of hazardous waste carefully, which adds additional costs. Thomas Fuchb, a medicinal chemist at the life sciences company Merck in Darmstadt, Germany, gave the example of making 3 kilograms of a drug molecule—with a raw material cost of $250,000. The palladium catalyst alone accounts for $100,000; extracting them from the product costs another $30,000. Finding a less toxic alternative to the metal could help reduce the environmental harm of palladium waste and move the chemical industry in a “greener” direction, says Tianning Diao, an organometallic chemist at New York University. The researchers hope to swap out palladium for more common metals, such as iron and nickel, or invent metal-free catalysts that bypass the problem entirely. Researchers have repeatedly reported the discovery of palladium-free catalysts over the past two decades. But it’s not uncommon for each discovered teaser to turn out to be a mistake.
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