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breaking bonds

During his sophomore year, Robert Richards ’12 realized that it would be good to get some experience conducting experiments outside of a controlled classroom environment. Because Ian Rhile, Ph.D., was his professor for freshman chemistry, Richards approached him to see if there was anything he needed help with.

As it turned out, Rhile, assistant professor of chemistry and biochemistry, was in the midst of a multi-year research project funded by a grant from the American Chemical Society-Petroleum Research Fund. He thought it would be the perfect fit for Richards, a chemistry major from Mount Bethel, Pa. So Rhile invited Richards to join his team, which has been working on removing the hydrogen atom from a carbon-hydrogen compound so they can replace it with another type of atom, such as oxygen.

Rhile explained that one of the biggest challenges in organic chemistry is to make molecules do what you want, and changing the carbon-hydrogen atom to some other type of atom would be very useful in that regard.

“All organic compounds—and a lot of other compounds as well —have a specific type of bonding called covalent bonding, where their electrons are shared between atoms,” Rhile said. “Carbonhydrogen bonds are among the most common in organic chemistry.

“Oftentimes you want to put other types of atoms where the hydrogen atoms are to make the compounds more useful for industrial or  pharmaceutical use. And if they’re pure carbon-hydrogen bonds they can be difficult to break.”

The first step in the process, called concerted proton electron transfer, is to introduce a receptor compound that will accept the hydrogen atom to make room for

The simpler compounds the team needs aren’t off-the-shelf products they could buy from a chemical catalog, so they had to design a synthesis to perform in the lab.

“Part of the research has been figuring out the synthesis of these molecules,” Rhile said. “Some we knew about in the literature, for some we had to come up with our own procedures based on literature procedures. We have made the molecule we want and observed the reactivity we expected. Now we’re doing some control experiments and other tests.”

While Rhile and his team have been experimenting with the compounds in the lab, Jeffrey Wolbach, Ph.D., and a separate team of student-scientists have been modeling the chemical reactions in their computer.

“We want to know the mechanism by which the hydrogen atom is being transferred,” said Wolbach, assistant professor of chemistry and biochemistry. “With the analytical instruments you can measure what you have to start with and what you have at the end. But it’s hard to measure how it gets from the beginning to the end.”

The advantage of using a computer program, Wolbach said, is that it can model characteristics of the reaction that can’t be observed experimentally. In this case, his team is interested in observing the transition state.

“When you get two molecules reacting there’s a point when you have something that both resembles the reactants and looks like  the products, but it’s really neither,” Wolbach explained. “You have a bunch of atoms glommed together, and that’s notoriously difficult to isolate experimentally.”

But they can be isolated computationally. “We can draw the reactants and we can draw the products, and the computer will find the transition state and tell us what it looks like,” Wolbach said. “It enables us to look at the transition state and come back with ideas of where we might be able to change the reactants to make the reaction go faster or better.”

“One of the goals of  the project is to develop a step-by-step description of how the chemicals are reacting,” Rhile added. “That’s what Dr. Wolbach is doing on the computer and what we’re trying to doexperimentally.” 

For Richards and the other students working on the project, it’s a chance to get experience they wouldn’t normally get in the classroom.

“In classroom settings you’re working on a lab that was designed to work so you know you’re going to get results,” Richards said. “Here we don’t know if our reactions are even going to work. It’s what we’re trying to figure out as part of our research. We’re going to get results, but we don’t know if they’re going to be what we want.

“We’re also using various instruments we have in the  department but don’t often use in class,” Richards added. “So we’re getting much more training on a lot of the instruments. And we’re using various organic synthesis techniques that I wouldn’t learn until advanced organic chemistry my senior year. Plus, we’re working a lot more independently than we would be in the lab.

”Brittney Tiley ’12, a chemistry major from Pottstown, Pa., who worked on Rhile’s team, presented her work at the National Conference on Undergraduate Research held at Ithaca College, Ithaca, N.Y., in April. In early June,  Rhile presented at the National Organic Symposium at Princeton University, Princeton, N.J.

The student-professor teams are continuing to work on their research during the summer months by experimenting with an expanded menagerie of compounds. n

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