Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Emory chemists reveal challenge to reaction theory

20.12.2004


For nearly 75 years, transition-state theory has guided chemists in how they view the way chemical reactions proceed. Recent research by Emory University chemists is challenging the long-held theory, showing that in some cases chemical reactions can proceed via a path that completely bypasses the "transition state."



"Our understanding of chemical reactions rests on the notion of the transition state. If we think of reactions as occurring on an energy landscape, the transition state is the ’mountain pass’ separating the reactants, and the resulting products from the reaction are valleys," says Joel Bowman, an Emory theoretical chemist and chairman of the chemistry department.

According to transition state theory, reactions proceed over this mountain pass, Bowman says, "but our results for a well-studied chemical reaction show that the reaction occurs during the transition state -- and also through a surprising second path that is not near this transition state region."


Bowman’s research, done in collaboration with physical chemist Arthur Suits of Wayne State University in Detroit, was published in the Nov. 12 issue of the journal Science, and was highlighted in the Nov. 15 issue of Chemical and Engineering News.

Using high-powered computational work and detailed experimental studies, the scientists demonstrated that formaldehyde (H2CO) exposed to light rays (or photoexcited) can decompose to hydrogen and carbon monoxide via a path that skirts that reaction’s well-established transition state entirely.

Using detailed pictures and measurements developed by Suits, Bowman performed high-level calculations to create a "movie" of this second pathway. The visual model reveals that one of formaldehyde’s hydrogen atoms breaks off and roams around before bumping into the second hydrogen atom and forming a hydrogen molecule (H2). At no point in this second pathway does the reaction go through its transition state.

Formaldehyde decomposition has long been a model system for those studying transition-state theory because the reaction is simple enough to treat with high-level theoretical models, and the products are easily detectable. Bowman’s research shows that such transition-state-skirting pathways may not be all that unusual in other chemical reactions.

"Although this discovery does not overturn traditional transition-state theory, our work is part of a growing body of evidence that is changing and expanding the way chemists and biochemists think about chemical reactions," Bowman says.

Beverly Cox Clark | EurekAlert!
Further information:
http://www.emory.edu

More articles from Life Sciences:

nachricht Ion treatments for cardiac arrhythmia — Non-invasive alternative to catheter-based surgery
20.01.2017 | GSI Helmholtzzentrum für Schwerionenforschung GmbH

nachricht Seeking structure with metagenome sequences
20.01.2017 | DOE/Joint Genome Institute

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Traffic jam in empty space

New success for Konstanz physicists in studying the quantum vacuum

An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Sustainable Water use in Agriculture in Eastern Europe and Central Asia

19.01.2017 | Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

 
Latest News

Helmholtz International Fellow Award for Sarah Amalia Teichmann

20.01.2017 | Awards Funding

An innovative high-performance material: biofibers made from green lacewing silk

20.01.2017 | Materials Sciences

Ion treatments for cardiac arrhythmia — Non-invasive alternative to catheter-based surgery

20.01.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>