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Brookhaven-developed Recyclable Catalyst May Help to Reduce Hazardous Industrial Waste

Catalysts at Work

“In making this recyclable catalyst, we had to understand the details of each bond-making and bond-breaking step of the individual reactions making up the catalytic cycle.”
- Vladimir Dioumaev

The new catalyst begins working as it mixes readily with the reactants. When the reaction is nearly complete, the catalyst begins to precipitate, yet it remains suspended within the reactants as an oily liquid clathrate clearly visible in the reaction tube. “The reagents penetrate the oil to keep reacting until the reactants are used up,” Dioumaev explains. When that happens, the catalyst is no longer soluble, so it precipitates out of the reaction as a solid, settling to the bottom of the test tube.

Further analysis revealed that virtually no trace of the catalyst is left in the liquid reaction products. This property is particularly desirable, for instance, in the creation of pharmaceutical compounds, which must be free of metal-based catalyst residue to be safe for use.

Now, the Brookhaven scientists will see if catalyst self-separation using liquid clathrate catalysts can be employed in other reactions. “At present, we are trying to determine the scope of reactions that can be carried out using this type of catalyst,” says Bullock. “In the future, we will seek to understand the criteria that influence the behavior of catalysts and their ability to mix with different solvents, which may allow us to design more catalysts that are readily recyclable.”

Meet Morris Bullock and Vladimir Dioumaev

Morris Bullock

Though the liquid in their test tubes has a purplish-red hue, Morris Bullock and Vladimir Dioumaev see only green — a fine example of “green chemistry,” that is.

“Our interest in developing readily recyclable catalysts and the use of solvent-free conditions arose out of the ‘green chemistry’ movement — the growing recognition of the importance of using chemical reactions that can contribute to a sustainable future by minimizing the generation of hazardous waste,” says Bullock, who has been a member of Brookhaven’s Chemistry Department since 1985.

“Green” chemistry is defined as the design of chemical processes and products that minimize or, ideally, eliminate the production of hazardous substances. That approach has multiple benefits, since avoiding both the production of waste and waste treatment can save the environment, lives, and money.

It was, in fact, the economical, practical idea of developing a self-separating catalyst that first drew the interest of Dioumaev, Bullock’s postdoctoral fellow. “Morris was the first to realize the environmental ‘green’ implications when I showed him how the catalyst self-separates,” Dioumaev says.

Vladimir Dioumaev

The team’s approach to designing catalysts is to use fundamental mechanistic information about the individual steps of the reactions and then to design catalysts that use those individual reactions.

“Our long-term goal is rationally to design catalysts that have high reactivity, but that, at the same time, are used in processes that are environmentally benign,” Bullock explains. Morris Bullock grew up in North Carolina and earned a B.S. in chemistry from the University of North Carolina at Chapel Hill in 1979, and a Ph.D. in chemistry from the University of Wisconsin–Madison in 1983. He did postdoctoral research at Colorado State University before coming to the Lab.

Vladimir Dioumaev did his undergraduate work at Moscow State University in his native Russia, before earning an M.S. in organic and organometallic chemistry through a joint program of Yale University and Moscow State University in 1988.

Dioumaev earned his Ph.D. in inorganic and polymer chemistry from McGill University in 1997 before coming to the United States. He joined the Lab’s Chemistry Department in 2001 and became a naturalized U.S. citizen in 2003.

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