Creating compounds with catalysts
The Radosevich Group uses innovative phosphorus catalysts to create new reactions
Courtesy of the Radosevich Group
Imagine a world where toxic chemicals abound in the air in the form of unfiltered carbon monoxide from car exhaust. Imagine a world without paper because the pulp cannot be refined into the crisp white sheets we have today. Imagine a world without fertilizer, gasoline, or even plastic. Imagine a world without life because the processes to replicate DNA now take 2.3 billion years. This is the reality of a world without catalysts, which are used to propel reactions in manufacturing, petrochemicals, the human body, and many other areas of life.
Although catalytic processes have become widespread over all industries, there are still many areas with potential for great advancements. The Radosevich Group, a synthetic chemistry laboratory led by Dr. Alexander Radosevich, PhD ’07, has been investigating the process of catalysis for nine years. A catalyst is a compound that can be used to increase the rate of a reaction without being consumed in the reaction itself. “We are interested in designing new reactions,” Radosevich said. By designing and improving catalysts, completely new compounds can be created.
In describing the setup of his lab, Radosevich noted that most of the equipment could easily be found in a standard teaching laboratory. What makes the Radosevich group lab unique are the tools, or catalysts, created through straightforward techniques. Radosevich compared his research to the construction of a building. While the tools used in construction are commonplace, the end-product can be elaborate and complex. Also, having simple tools and processes allows for the catalysts to be easily reproduced in a commercial setting. Radosevich states that “the point of reaction chemistry that we develop is to be used by other people."
The Radosevich group focuses on the creation of catalysts with phosphorus compounds. Phosphorus is a unique catalytic element because, although it is a non-metal, it has multiple oxidation states like a transition metal, which make up most catalysts. For example, a rhodium catalyst is used in the catalytic converters of cars to filter the exhaust. However, transition metals can be rare and expensive. In contrast, phosphorus is abundant and inexpensive. Phosphorus’s free ability to cycle through oxidation states allows it to act similarly to transition-metal catalysts. Additionally, organophosphorus molecules, which are molecules that contain both carbon and phosphorus, have useful spectroscopic properties. Spectroscopy uses electromagnetic radiation to identify compounds.
After completing a round of experiments, the researchers used various spectroscopic techniques to indirectly identify the compounds created. The most abundant isotope of phosphorus, 31P, is easily identified by the spectroscopic techniques used, which allow the compounds to be characterized very easily. Identifying and characterizing the compounds created allow the researchers understand more about the compound and which reactions it would best optimize as a catalyst.
The organophosphorus molecules created by the Radosevich group have applications in many fields, one such field being the pharmaceutical industry. By treating organic compounds containing nitrogen dioxide with nitric acid and then introducing a phosphorus catalyst, reactive nitrogen intermediates are produced. These nitrogen intermediates can then be reacted to form other compounds. The catalysis of these reactions is important in pharmaceuticals, as many drugs contain nitrogen. Finding an easy and efficient way to separate nitrogen is valuable for drug discovery.
In the future, Dr. Radosevich hopes to expand his research from catalytic synthesis with phosphorus to other equally abundant, non-metal compounds such as silicon or sulfur. He would also like to investigate the compounds he creates in his lab through the broader lens of reactivity rather than just catalysis. “At root,” says Radosevich, “I’m interested in reactions.”