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Scientists convert deadly gas to harmless powder

Using a ground-breaking method that is both new and inexpensive, Aarhus researchers have encapsulated the poisonous gas carbon monoxide (CO) in a powder, making it easy to work with. The method has just been presented in an article published in the highly reputed Journal of the American Chemical Society (JACS) and is expected to have significant influence on the production of organic molecules and research into them. In collaboration with Aarhus University, the researchers have therefore applied for a patent on both the process and the equipment used to release CO.

2011.04.12 | Christina Troelsen

The deadly gas carbon monoxide as a powder.

Outline of the reaction. Carbon monoxide (CO) molecules are formed in one chamber. They are subsequently led to a reaction chamber, where they are put into the desired organic molecule. Both processes are catalysed by the catalytic metal palladium.

An example of a palladium-catalysed reaction. The scientists succeeded here in putting a so-called olefin on a benzene ring by means of a palladium atom.

The researchers from the Department of Chemistry who are responsible for developing the new powder. Front row from left: Stig Friis, Dennis Nielsen, middle row: Thomas Gøgsig, Philippe Hermange, at the back: Anders Lindhardt, Klaus Bjerglund and Troels Skrydstrup. The team also includes Mia Burhardt and Rolf Taaning (not pictured). Photo: Niels Jørgen Hansen (Department of Chemistry).

See video interview with Professor Troels Skrydstrup
Every year, carbon monoxide costs the lives of many hundreds of people all over the world. This most frequently occurs when people burn coal or wood in enclosed spaces, such as lighting a barbecue indoors. CO is emitted in this process, and can lead to headache, exhaustion and finally death.

Because the gas is extremely harmful to health, chemists have found it difficult and complicated to work with. The new method makes the processes much more easily accessible and safe. The method was developed by a team of scientists at the Centre for Insoluble Protein Structure (inSPIN), the Interdisciplinary Nanoscience Centre (iNANO), and the Department of Chemistry, Aarhus University, headed by Professor Troels Skrydstrup.

Easier to handle dangerous gas

For many years, chemists have used CO as a building block in the production of large organic molecules, i.e. molecules that contain carbon. However, as mentioned above, the gas has the disadvantage of being extremely dangerous for humans and animals if too large amounts are inhaled.

At the same time, the gas is colourless, odourless and tasteless, and symptoms are first observed a relatively long time after inhalation. It has therefore been necessary to use specially designed equipment accompanied by CO detectors when working with the gas. All this has made working with the gas so difficult that its application is not nearly as widespread as its beneficial properties entitle it to be.

The discovery is based on a special, harmless powder the scientists succeeded in producing. Under the right conditions, the powder can be converted to carbon monoxide gas. The method published by the researchers utilises a two-chamber system in which the gas is produced in one of the chambers. This gas-producing chamber is adjacent to the actual reaction chamber in which someone may want to use the CO. The amount of gas produced can be regulated by controlling the amount of powder measured, thus making it possible to liberate small and very precise amounts.

This means that CO detectors are not necessary, and neither is expensive equipment for storing the gas at high pressure. In addition, the method means that chemists all over the world no longer need to find chemical alternatives to avoid using CO gas, which saves both time and money in the long run.

Based on Nobel Prize

The method is an extension of a chemical process developed in the 1970s, which was awarded the Nobel Prize in Chemistry 2010. The technology is based on the use of the element palladium, which has proved to be extremely effective for incorporating CO into organic molecules (see fact box). The silver shiny palladium is used to catalyse the process, which means it induces or accelerates the formation of an abundance of organic molecules.

Facts – palladium chemistry
Palladium is used as a catalyst of the so-called cross-couplings. When two carbon atoms meet, there is normally no reason for them to react to each other. When they get close to palladium, however, they both initially bind to the metal, which subsequently binds the carbon atoms together. At the same time, the palladium is regenerated and can form part of the next reaction.

By adding CO to an organic molecule, the addition involves not just an extra carbon atom, but also a chemical group (carbonyl – a carbon atom bound to an oxygen atom by two bonds), and this is extremely practicable in connection with further work involving the molecule. At the same time, the carbonyl group is often found in chemical combinations that work on or with biological systems such as medicines. The researchers at iNANO, Aarhus University, can thus easily and efficiently produce a considerable number of molecules that are otherwise difficult to form. Molecules produced by this method would require a number of extra reactions to be produced under other circumstances. And these extra reactions often mean that less material is produced and at a higher price.

Atomic tag on molecules

The method also makes it possible for scientists to incorporate carbon isotope C13 in their molecules. The incidence of C13 in nature is only1.1%.

C13 is used for a technique called nuclear magnetic resonance (NMR), which examines how the atomic cores ‘rotate’. This provides information about which atoms are located around the C13 atom (see fact box). In other words, it makes it possible to determine the structure of the molecule.

Facts – nuclear magnetic resonance (NMR)
NMR is used to get information about which atoms are found in a molecule, and how they are placed in relation to each other. The technique makes use of the fact that magnetic cores in a strong magnetic field are capable of absorbing and discharging electromagnetic energy. The way they do this depends on the adjacent atoms, and information is thus acquired regarding the composition and structure. NMR is also the principle behind MRI scannings, which are used by the health services.

The researchers are also in the process of extending the technique to incorporate radioactive CO into organic molecules. In this case, they use the radioactive carbon isotopes C11 and C14. Radioactive molecules are used in a considerable number of contexts, including studies of how biologically active substances such as pharmaceuticals and agricultural chemicals are degraded in the body and in nature. Such studies are necessary in the development of new and less harmful biologically active substances.

The radioactively tagged substances are also regularly utilised for the positron emission tomography (PET) scanning technique used in hospitals all over the world for diagnosing cancer.

Facts – positron emission tomography (PET)
The PET technique can create images of processes in the body. A so-called tracer molecule is used in this process, and it is tagged with a special radioactive atom that can target specific processes/tissues in the body. After a certain time, the tracer atom emits a special kind of radiation that can be detected and used to make 3D images.

The researchers have submitted a patent application

In addition to publishing the discovery and in collaboration with Aarhus University, the researchers have applied for a patent on both the process and the equipment used to release CO. This technology is expected to form the basis for setting up a company to handle CO-based processes using the different carbon isotopes.

Written in collaboration with Professor Troels Skrydstrup, Postdoctoral Scholar Anders Lindhardt, Postdoctoral Scholar Rolf Taaning and PhD Student Thomas Gøgsig, as well as Nanovidensbank.dk .


For more information, please contact

Professor Troels Skrydstrup
Centre for Insoluble Protein Structure (inSPIN), iNANO and Department of Chemistry
Aarhus University
Tel: +45 8942 3932
Mobile: 2899 2132
E-mail: ts@chem.au.dk

See video interview with Professor Troels Skrydstrup (in Danish only):

Links

Chemical and Engineering News, 11 April 2011: Safer Carbonylations. Synthesis: New approach could ease small-scale carbon monoxide reactions

Ingeniøren, 12 April (in Danish only): Aarhus researchers convert carbon monoxide to harmless powder

Scientific article in Journal of the American Chemical Society (JACS): Carbonylative Heck Reactions Using CO Generated ex Situ in a Two-Chamber System


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Revised 2014.04.22

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