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 'Lipid asymmetry' plays key role in activating immune cells
20.02.2018 | Biophysical Society

nachricht New printing technique uses cells and molecules to recreate biological structures
20.02.2018 | Queen Mary University of London

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: In best circles: First integrated circuit from self-assembled polymer

For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.

In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...

Im Focus: Demonstration of a single molecule piezoelectric effect

Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale

Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...

Im Focus: Hybrid optics bring color imaging using ultrathin metalenses into focus

For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.

But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...

Im Focus: Stem cell divisions in the adult brain seen for the first time

Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.

The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...

Im Focus: Interference as a new method for cooling quantum devices

Theoretical physicists propose to use negative interference to control heat flow in quantum devices. Study published in Physical Review Letters

Quantum computer parts are sensitive and need to be cooled to very low temperatures. Their tiny size makes them particularly susceptible to a temperature...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on High Temperature Shape Memory Alloys (HTSMAs)

15.02.2018 | Event News

Aachen DC Grid Summit 2018

13.02.2018 | Event News

How Global Climate Policy Can Learn from the Energy Transition

12.02.2018 | Event News

 
Latest News

'Lipid asymmetry' plays key role in activating immune cells

20.02.2018 | Life Sciences

MRI technique differentiates benign breast lesions from malignancies

20.02.2018 | Medical Engineering

Major discovery in controlling quantum states of single atoms

20.02.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>