New chemistry study challenges fundamental mechanism

As one of the fundamental disciplines that help us understand the physical world and how it works, organic chemistry plays an essential role in both our instruction and research missions. So it is significant that researchers continue to test and challenge this crucial area of study at its most basic levels:

A family of millions of known chemical compounds called "aromatics" or "arenes" and their products, including a great number of medicines, plastics and synthetic fibers, are characterized by their regular arrangement of ring atoms instead of alternating single and double bonds. A new study published by researchers in the University of Georgia Franklin College of Arts and Sciences department of chemistry posits a different fundamental mechanism for the way these compounds react to replace atoms.

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Aromatics constitute a diverse and widely used chemical family. Employed to make derivatives, benzene consistently ranks among the top 20 chemicals produced annually.

The key chemical reaction giving these derivatives depends on the underlying ring structure. "Electrophilic aromatic substitution" describes the reaction whereby an atom of an aromatic is replaced by another of an "electron-seeking" reagent. This fundamental organic chemical reaction of aromatics is the focus of the paper.

"The electrophile is supposed to attach itself to the aromatic in a first stage to give an ‘intermediate,' from which another group, present at the same site, is then lost in a second stage," said Paul von Ragué Schleyer, Graham Perdue Professor of Chemistry at UGA and one of the study's authors. "Although this putative intermediate has garnered much attention in the literature as a simplification, we find instead that it doesn't exist when the reaction conditions are modeled computationally."

Re-evaluting how this fundamentally discipline itself works only reinforces its reliability and rigor, as well as the theories and products that derive therein. Significantly, when reseachers of the caliber of Schaefer, Schleyer and their internaitonal colleagues publish the results of their investigations, the scientific community takes notice. This is a major contribution to the overall body of knowledge and we are proud of and humbled by their ongoing scholarship on both a fundamnental level and an over-arching plane.

For more on the UGA Center for Computational Quantum Chemistry, visit here.