BY DAWN LEVY
President Bush today named John Brauman, the J.G. Jackson and C.J. Wood Professor of Chemistry, as one of eight pioneering researchers to receive the 2002 National Medal of Science.
"Brauman advanced scientific knowledge by demonstrating differences in chemical reactivity in the presence or absence of solvent, making it possible to infer the role solvent plays in chemical stability and reactivity," lauded a White House press release. "He developed techniques for exploring and enhancing understanding of energy transfer and its effects on chemical dynamics."
Established by Congress in 1959, the medal is the nation's highest scientific honor. For a complete list of winners, see http://www.nsf.gov/nsb/awards/nms/medal.htm.
Brauman's medal brings the number awarded to Stanford including the Hoover Institution to 30.
Richard N. Zare, the Marguerite Blake Wilbur Professor in Natural Science at Stanford and a 1983 winner of the National Medal of Science, called Brauman's contributions to the field "spectacular," saying they changed the way chemists regard the properties of ions and the mechanisms of ion-molecule reactions. "No person has done more to help us understand the important role solvent molecules play in ion chemistry than John Brauman," he said.
"John Brauman has made major contributions to chemistry, in particular the field of ionic reactions and the crucial role of the medium in which these reactions occur," said John Ross, the Camille and Henry Dreyfus Professor of Chemistry at Stanford and a 1999 winner of the National Medal of Science. "His work provides a basic framework for understanding and predicting so much of solution and gas-phase reactions."
Chemical reactions can take place in solvents or solids, and the reactants often are not electrically neutral. To the contrary, they have charges that can interact very strongly with the solvents.
Brauman explained his work during an interview in his office in the Mudd Building. "One of the problems is when you make an observation -- how strong an acid is or how fast a reaction goes or how the reaction rate depends on the structure -- what you see is a combination of what the reactivity would have been without the solvent plus what the solvent is doing," he said. "What our research has been all about is trying to take those two things apart by looking at those reactions where there isn't any solvent around."
Looking at reactions essentially in a vacuum -- out of the context in which they occur in, say, biological or industrial solvents -- Brauman has learned a lot about their intrinsic reactivity. By demonstrating differences in chemical reactivity in the presence or absence of solvent, he has been able to infer the role solvent plays in chemical stability and reactivity.
To carry out an experiment that will allow study of a reaction without any solvent around requires a special technology that puts the charged reactants in a gaseous state. One example of that technology, developed in the 1960s, ion cyclotron resonance mass spectrometry, was developed by former Stanford faculty member John Baldeschwieler (now at Caltech), who won the National Medal of Science in 2000. Brauman used it to look at simple organic acids and bases undergoing reactions in a vacuum, which gave him a unique window into the equilibria and kinetics of the chemical reactions.
"One thing that makes organic chemistry interesting, in part, is the small structural changes you can make and the way the systems respond," Brauman said. "The reason our work was initially startling was that people made observations [in solvent] about what was a strong acid and what was a weaker acid and then tried to make hypotheses about the origin of these effects. And as it happens, if you take the solvent away then the effects are sometimes different."
He was first to show that many simple organic compounds have reversed acidity and basicity between the gas and liquid phase, and that meant that some hypotheses about acid/base chemistry, based on simplistic models, had to be wrong. The new knowledge created by his fundamental research has had profound effects on organic and biological chemistry and related fields.
"Brauman was able to rationalize both the gas phase and the solution behavior -- and he put them on a much more substantial footing," Zare said. "He subsequently developed powerful methods for describing solvation effects in ionic reactions. In recent work, he has shown that simple hydrogen-bonded complexes can have structures and properties that are quite different from those predicted by simple models. This work promises to make our pictures of hydrogen bonding much clearer."
In related work, Brauman studied how much energy it took to remove electrons from negative ions -- a measure of their absolute energetics. Determining accurate electron affinities of many molecules has provided new insights into the energetics of negatively charged ions. In addition, Brauman has undertaken studies to explore and understand energy transfer and its effects on reaction dynamics.
Born in Pittsburgh on Sept. 7, 1937, Brauman received his bachelor's degree in chemistry from MIT in 1959 and his doctorate in chemistry from the University of California-Berkeley in 1963. He completed a National Science Foundation postdoctoral fellowship at the University of California-Los Angeles before coming to Stanford, where he worked as an assistant professor (1963-1969), associate professor (1969-1972) and professor (1972 to present). He served as Chemistry Department chair from 1979 to 1983 and from 1995 to 1996 and as cognizant dean for natural sciences from 1999 to 2003.
Brauman's numerous awards include the Willard Gibbs Medal, the Linus Pauling Medal, the James Flack Norris Award in Physical-Organic Chemistry, the Arthur C. Cope Scholar Award, the Harrison Howe Award and the Award in Pure Chemistry -- all from the American Chemical Society -- as well as the National Academy of Sciences Award in the Chemical Sciences and a Dean's Award for Distinguished Teaching from Stanford.
He is a member of the American Academy of Arts and Sciences, a fellow of the American Association for the Advancement of Science and the American Chemical Society, an honorary fellow of the California Academy of Sciences and a member and home secretary of the National Academy of Sciences.
Author of more than 300 publications, Brauman has chaired Science magazine's senior editorial board since 2001, and was the magazine's deputy editor for physical sciences from 1985 to 2000.
Stanford Report, October 29, 2003