Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Conifer Scent Influences Climate

10.01.2014
Detection by IR: The ozonolysis of terpenes forms Criegee intermediates that oxidize SO2

Conifers emit volatile hydrocarbons, primarily terpenes, which we experience as the characteristic smell of the woods.



In a complicated series of reactions involving ozone and sulfur dioxide, these compounds may be involved in the formation of aerosols that counteract the greenhouse effect. German scientists have now been able to follow the reaction of a terpene with ozone in the laboratory by using infrared (IR) spectroscopy.

As they report in the journal Angewandte Chemie, they were able to identify critical intermediates of this process, namely the Criegee intermediates. They were also able to verify that these intermediates react very efficiently with sulfur dioxide.

Terpenes have a strong influence on the chemical processes that occur in the earth’s atmosphere, even though they are only present in trace amounts. Particularly in summer, these compounds are involved in the ozone chemistry of the troposphere. It has been shown that their oxidation plays a large role in the formation of secondary organic aerosols (SOAs), which influence our climate.

These processes have not yet been completely explained and represent a large source of uncertainty in climate-prediction models. Researchers working with Thomas Zeuch at the University of Göttingen and the Karlsruhe Institute of Technology (KIT) have now gained new insights into the reactions of terpenes with ozone.

SOAs are liquid or solid particles that contain sulfuric acid (H2SO4) and are formed from gaseous precursors such as sulfur dioxide (SO2) and terpenes. Atmospheric sulfuric acid and the sulfuric acid and sulfate aerosol particles that are formed from it also contribute to acid rain. “At the same time, they work against the greenhouse effect,” explains Zeuch, “because they both promote cloud formation and reflect the sun’s radiation back into space.”

How does sulfuric acid get into the troposphere? “In addition to a sequence of reactions that starts with the oxidation of sulfur dioxide by hydroxyl radicals, an alternative pathway of oxidation by Criegee intermediates (CIs) has been proposed,” says Zeuch. These compounds are carbonyl oxides with two free-radical centers that account for their unusual chemistry. They are formed by the reaction of ozone with the double bonds in organic compounds such as terpenes. Until now, only small CIs formed through photolysis have been directly detected. In their study, Zeuch and his co-workers have now examined the reactions of the terpene called β-pinene, which is often found in plants, with ozone.

“By using IR spectroscopy, we were able to detect large, stabilized CIs formed during the ozonolysis of pinene for the first time,” reports Zeuch. “These large CIs reacted with sulfur dioxide to form sulfur trioxide with a yield of over 80 %. Time-resolved experiments revealed that this reaction is very fast.” This unequivocally proves that SO2 is efficiently oxidized to tropospheric sulfuric acid by reaction with stabilized Criegee intermediates from terpenes.

About the Author
Dr. Thomas Zeuch is group leader and lecturer at the Institute of Physical Chemistry, Göttingen University. The research in his team is dedicated to unravel the chemistry behind the formation of new particles in air. Zeuch and his co-workers try to trace this chemistry on the microscopic level by means of new infrared spectroscopic methods.

Author: Thomas Zeuch, Universität Göttingen (Germany), http://www.uni-pc.gwdg.de/zeuch/

Title: Infrared Detection of Criegee Intermediates Formed during the Ozonolysis of β-Pinene and Their Reactivity towards Sulfur Dioxide

Angewandte Chemie International Edition, Permalink to the article: http://dx.doi.org/10.1002/anie.201307327

Thomas Zeuch | Angewandte Chemie
Further information:
http://pressroom.angewandte.org

More articles from Life Sciences:

nachricht More than just a mechanical barrier – epithelial cells actively combat the flu virus
04.05.2016 | Helmholtz-Zentrum für Infektionsforschung

nachricht Discovery of a fundamental limit to the evolution of the genetic code
03.05.2016 | Institute for Research in Biomedicine (IRB Barcelona)

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Nuclear Pores Captured on Film

Using an ultra fast-scanning atomic force microscope, a team of researchers from the University of Basel has filmed “living” nuclear pore complexes at work for the first time. Nuclear pores are molecular machines that control the traffic entering or exiting the cell nucleus. In their article published in Nature Nanotechnology, the researchers explain how the passage of unwanted molecules is prevented by rapidly moving molecular “tentacles” inside the pore.

Using high-speed AFM, Roderick Lim, Argovia Professor at the Biozentrum and the Swiss Nanoscience Institute of the University of Basel, has not only directly...

Im Focus: 2+1 is Not Always 3 - In the microworld unity is not always strength

If a person pushes a broken-down car alone, there is a certain effect. If another person helps, the result is the sum of their efforts. If two micro-particles are pushing another microparticle, however, the resulting effect may not necessarily be the sum their efforts. A recent study published in Nature Communications, measured this odd effect that scientists call “many body.”

In the microscopic world, where the modern miniaturized machines at the new frontiers of technology operate, as long as we are in the presence of two...

Im Focus: Tiny microbots that can clean up water

Researchers from the Max Planck Institute Stuttgart have developed self-propelled tiny ‘microbots’ that can remove lead or organic pollution from contaminated water.

Working with colleagues in Barcelona and Singapore, Samuel Sánchez’s group used graphene oxide to make their microscale motors, which are able to adsorb lead...

Im Focus: ORNL researchers discover new state of water molecule

Neutron scattering and computational modeling have revealed unique and unexpected behavior of water molecules under extreme confinement that is unmatched by any known gas, liquid or solid states.

In a paper published in Physical Review Letters, researchers at the Department of Energy's Oak Ridge National Laboratory describe a new tunneling state of...

Im Focus: Bionic Lightweight Design researchers of the Alfred Wegener Institute at Hannover Messe 2016

Honeycomb structures as the basic building block for industrial applications presented using holo pyramid

Researchers of the Alfred Wegener Institute (AWI) will introduce their latest developments in the field of bionic lightweight design at Hannover Messe from 25...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

The “AC21 International Forum 2016” is About to Begin

27.04.2016 | Event News

Soft switching combines efficiency and improved electro-magnetic compatibility

15.04.2016 | Event News

Grid-Supportive Buildings Give Boost to Renewable Energy Integration

12.04.2016 | Event News

 
Latest News

New fabrication and thermo-optical tuning of whispering gallery microlasers

04.05.2016 | Physics and Astronomy

Introducing the disposable laser

04.05.2016 | Physics and Astronomy

A new vortex identification method for 3-D complex flow

04.05.2016 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>