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 New Computer Model Could Explain how Simple Molecules Took First Step Toward Life
29.07.2015 | Brookhaven National Laboratory

nachricht Switch for building barrier in roots
29.07.2015 | The University of Tokyo

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Superfast fluorescence sets new speed record

Plasmonic device has speed and efficiency to serve optical computers

Researchers have developed an ultrafast light-emitting device that can flip on and off 90 billion times a second and could form the basis of optical computing.

Im Focus: Unlocking the rice immune system

Joint BioEnergy Institute study identifies bacterial protein that is key to protecting rice against bacterial blight

A bacterial signal that when recognized by rice plants enables the plants to resist a devastating blight disease has been identified by a multi-national team...

Im Focus: Smarter window materials can control light and energy

Researchers in the Cockrell School of Engineering at The University of Texas at Austin are one step closer to delivering smart windows with a new level of energy efficiency, engineering materials that allow windows to reveal light without transferring heat and, conversely, to block light while allowing heat transmission, as described in two new research papers.

By allowing indoor occupants to more precisely control the energy and sunlight passing through a window, the new materials could significantly reduce costs for...

Im Focus: Simulations lead to design of near-frictionless material

Argonne scientists used Mira to identify and improve a new mechanism for eliminating friction, which fed into the development of a hybrid material that exhibited superlubricity at the macroscale for the first time. Argonne Leadership Computing Facility (ALCF) researchers helped enable the groundbreaking simulations by overcoming a performance bottleneck that doubled the speed of the team's code.

While reviewing the simulation results of a promising new lubricant material, Argonne researcher Sanket Deshmukh stumbled upon a phenomenon that had never been...

Im Focus: NASA satellite camera provides 'EPIC' view of Earth

A NASA camera on the Deep Space Climate Observatory (DSCOVR) satellite has returned its first view of the entire sunlit side of Earth from one million miles away.

The color images of Earth from NASA's Earth Polychromatic Imaging Camera (EPIC) are generated by combining three separate images to create a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

3rd Euro Bio-inspired - International Conference and Exhibition on Bio-inspired Materials

23.07.2015 | Event News

Clash of Realities – International Conference on the Art, Technology and Theory of Digital Games

10.07.2015 | Event News

World Conference on Regenerative Medicine in Leipzig: Last chance to submit abstracts until 2 July

25.06.2015 | Event News

 
Latest News

A New Litmus Test for Chaos?

29.07.2015 | Physics and Astronomy

New Computer Model Could Explain how Simple Molecules Took First Step Toward Life

29.07.2015 | Life Sciences

New ERC calls published under Horizon 2020

29.07.2015 | Awards Funding

VideoLinks
B2B-VideoLinks
More VideoLinks >>>