Simple Cobalt Catalyst Unlocks Hard-to-Use Chemical Building Blocks
Chemists have long known that some of the most common building blocks for making medicines, materials and industrial chemicals—compounds called alkyl chlorides—are surprisingly difficult to work with. Now researchers in the UNC Department of Chemistry, including Ph.D. student John Brymer, above, report a new catalytic method that may finally make these abundant chemicals far easier to use.
March 8, 2026 I By Dave DeFusco
Chemists have long known that some of the most common building blocks for making medicines, materials and industrial chemicals—compounds called alkyl chlorides—are surprisingly difficult to work with. Now researchers in the UNC Department of Chemistry report a new catalytic method that may finally make these abundant chemicals far easier to use.
The study, published in the Journal of the American Chemical Society, describes how a simple cobalt-based catalyst, known as a cobaloxime, can help link carbon atoms together or remove chlorine atoms from these compounds under mild, practical conditions. The reactions even tolerate air and water, something many traditional catalysts cannot handle.
That practicality is part of what makes alkyl chlorides appealing in the first place. As lead author John Brymer, a Ph.D. student in the Department of Chemistry, explained in the paper, their stability is actually an advantage despite making them harder to activate chemically.
“Because they don’t react as easily, alkyl chlorides last longer in storage and are easier to handle,” said Brymer. “That stability means far more of them are available for scientists to buy and use—roughly 200,000 more kinds than similar chemicals called bromides or iodides. Their stability also means the leftover substances they produce tend to be less toxic.”
Traditionally, chemists have relied on expensive metals such as palladium to perform reactions similar to those described in the study. Those catalysts often require carefully controlled conditions that exclude air and moisture, increasing cost and complexity. Brymer said the cobalt alternative offers clear advantages.
“Palladium is much more expensive than cobalt,” he said. “Typically these systems don’t tolerate air and water that well, so the fact that the cobaloxime is able to tolerate air and water fine, and is significantly cheaper and more abundant, makes it desirable.”
The research team demonstrated that the catalyst can drive two useful types of reactions. One is a variation of the Mizoroki–Heck reaction, which forms new carbon-carbon bonds, a cornerstone of modern synthetic chemistry. The other removes hydrogen and chlorine atoms from molecules to form alkenes, a process called dehydrohalogenation.
A key feature of the new chemistry is the use of visible light to help activate the catalyst. Light provides energy that helps break a temporary bond between cobalt and carbon, allowing the reaction to proceed.
“You can break it by giving it energy either in the way of heat or light,” said Brymer. “Using both in our case has proven to be the most effective. The dehydrohalogenations and intermolecular couplings only work with irradiation.”
This means relatively gentle conditions can replace harsher chemical treatments often needed in similar reactions. Another crucial discovery involved something seemingly simple: an added electrolyte, specifically tetrabutylammonium chloride (TBACl). This salt helps zinc, which is a chemical that powers the reaction, restore the cobalt catalyst to its active form so it can keep doing its job again and again.
“Normally, zinc doesn’t have enough chemical strength to switch the cobalt catalyst back into its active form,” said Brymer. “Adding the electrolyte makes that possible, so the catalyst can keep working through the reaction cycle. Without it, many of the reactions hardly happen at all.”
The researchers also found the method produces fewer unwanted byproducts than earlier approaches. That selectivity is important when synthesizing complex molecules such as pharmaceuticals. “We’re able to selectively get the product we want without as many byproducts,” said Brymer, adding that earlier systems often produced large amounts of unwanted alkane products.
The reactions also tolerate sensitive chemical groups, such as alcohols, ketones and esters, which are common in biologically active molecules. That flexibility could make the chemistry useful in drug discovery and materials science.
Erik Alexanian, professor of chemistry at UNC and Brymer’s advisor, emphasizes that the broader significance lies in showing that abundant “first-row” metals, like cobalt, are cheaper, more readily available alternative that could make important chemical processes more affordable and sustainable. Demonstrating practical alternatives, he said, helps expand the toolkit for more sustainable and economical chemical synthesis.
“It’s just once again showing that you don’t need to rely on palladium systems to do interesting transformations,” said Alexanian, “opening up more examples of much cheaper first-row metals working just adds another example to that.”