Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Chemical juggling with three particles

24.05.2019

Chemists from the University of Bonn and their US colleagues at Columbia University in New York have discovered a novel mechanism in catalysis. It allows the synthesis of certain alcohols more cheaply and environmentally friendly than before. The reaction follows a previously unknown pattern in which hydrogen is split into three components in a time-coordinated manner. More than five years passed between the idea and its practical realization. The results are published in the prestigious journal Science.

Alcohols are common chemical compounds which, in addition to carbon and hydrogen, contain at least one OH group. They serve as starting materials for a whole series of chemical syntheses and are often produced directly from olefins by addition of water (chemical formula: H2O).


Prof. Dr. Andreas Gansäuer and Anastasia Panfilova during epoxy hydrogenation at the Kekulé Institute of Organic Chemistry and Biochemistry at the University of Bonn.

© Photo: Volker Lannert/Uni Bonn

Olefins are hydrocarbons with a double bond available from oil. The water molecule serves as a “donor” of the OH-group characteristic of alcohols.

This synthesis is simple and efficient, but it has a decisive disadvantage: It can only be used to produce certain alcohols, the so-called “Markovnikov alcohols”.

The OH group cannot simply be attached to any position of the olefin – one of two positions is excluded. “We have now found a new catalytic method that can produce exactly these ‘impossible’ alcohols,” explains Prof. Dr. Andreas Gansäuer.

Gansäuer works at the Kekulé Institute of Organic Chemistry and Biochemistry at the University of Bonn. The idea for the new synthesis emerged in 2013 in a collaboration with the group of Prof. Dr. Jack Norton of Columbia University in New York.

However, it took almost five years until the synthesis of the so-called “anti-Markovnikov alcohol” using the new catalytic system worked well enough to be published.

Acceleration and slowing down by the catalysts’ ligands

The fact that the two groups succeeded in making it into the renowned journal ‘Science’ is due to the unusual reaction mechanism. Epoxides, common and valuable intermediate products of the chemical industry, serve as starting materials. Epoxides can be produced by adding an oxygen atom (chemical symbol: O) to olefins. If they are allowed to react with hydrogen molecules (H2), the oxygen becomes an OH group. Normally, with this approach only Markovnikov alcohols are produced.

“In our reaction, however, we successively transfer the hydrogen in three parts,” explains Gansäuer. “First a negatively charged electron, then a neutral hydrogen atom and finally a positively charged hydrogen ion, a proton. We use two catalysts, one of which contains titanium and the other chromium. “This allows us to convert epoxides into anti-Markovnikov alcohols.”

The timing of the entire process must be strictly coordinated - like in juggling, where each ball has to maintain a specified flight duration. To achieve this, the chemists had to synchronize the speed of three catalytic reactions. To this end, they attached the ‘right’ ligands, molecules that control the metals’ reactivity, to the titanium and chromium atoms.

Until now, anti-Markovnikov alcohols have been produced through a so-called hydroboration followed by an oxidation. However, this reaction is relatively complex and not particularly sustainable. The new mechanism, on the other hand, does not produce any by-products and is thus practically waste-free. “Titanium and chromium are also very common metals, unlike many other noble metals that are often used in catalysis,” Gansäuer emphasizes.

In 2013, Norton and Gansäuer submitted their idea to a call for proposals on sustainable catalysis by the International Union of Pure and Applied Chemistry (IUPAC), winning first place. The project was largely financed with the grant money. “But the good cooperation within my institute has certainly also contributed to the success,” emphasizes Gansäuer. “For instance, I had access not only to the institute's resources, but also to equipment of the other groups from Bonn.”

Wissenschaftliche Ansprechpartner:

Prof. Dr. Andreas Gansäuer
Kekulé Institute of Organic Chemistry and Biochemistry
University of Bonn
Tel. +49(0)228/732800
E-mail: andreas.gansaeuer@uni-bonn.de

Originalpublikation:

Chengbo Yao, Tobias Dahmen, Andreas Gansäuer, Jack Norton: Anti-Markovnikov alcohols via epoxide hydrogenation through cooperative catalysis. Science, DOI: 10.1126/science.aaw3913

Johannes Seiler | idw - Informationsdienst Wissenschaft
Further information:
http://www.uni-bonn.de/

More articles from Life Sciences:

nachricht Monitoring biodiversity with sound: how machines can enrich our knowledge
18.06.2019 | Georg-August-Universität Göttingen

nachricht Uncovering hidden protein structures
18.06.2019 | Universität Konstanz

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: The hidden structure of the periodic system

The well-known representation of chemical elements is just one example of how objects can be arranged and classified

The periodic table of elements that most chemistry books depict is only one special case. This tabular overview of the chemical elements, which goes back to...

Im Focus: MPSD team discovers light-induced ferroelectricity in strontium titanate

Light can be used not only to measure materials’ properties, but also to change them. Especially interesting are those cases in which the function of a material can be modified, such as its ability to conduct electricity or to store information in its magnetic state. A team led by Andrea Cavalleri from the Max Planck Institute for the Structure and Dynamics of Matter in Hamburg used terahertz frequency light pulses to transform a non-ferroelectric material into a ferroelectric one.

Ferroelectricity is a state in which the constituent lattice “looks” in one specific direction, forming a macroscopic electrical polarisation. The ability to...

Im Focus: Determining the Earth’s gravity field more accurately than ever before

Researchers at TU Graz calculate the most accurate gravity field determination of the Earth using 1.16 billion satellite measurements. This yields valuable knowledge for climate research.

The Earth’s gravity fluctuates from place to place. Geodesists use this phenomenon to observe geodynamic and climatological processes. Using...

Im Focus: Tube anemone has the largest animal mitochondrial genome ever sequenced

Discovery by Brazilian and US researchers could change the classification of two species, which appear more akin to jellyfish than was thought.

The tube anemone Isarachnanthus nocturnus is only 15 cm long but has the largest mitochondrial genome of any animal sequenced to date, with 80,923 base pairs....

Im Focus: Tiny light box opens new doors into the nanoworld

Researchers at Chalmers University of Technology, Sweden, have discovered a completely new way of capturing, amplifying and linking light to matter at the nanolevel. Using a tiny box, built from stacked atomically thin material, they have succeeded in creating a type of feedback loop in which light and matter become one. The discovery, which was recently published in Nature Nanotechnology, opens up new possibilities in the world of nanophotonics.

Photonics is concerned with various means of using light. Fibre-optic communication is an example of photonics, as is the technology behind photodetectors and...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

SEMANTiCS 2019 brings together industry leaders and data scientists in Karlsruhe

29.04.2019 | Event News

Revered mathematicians and computer scientists converge with 200 young researchers in Heidelberg!

17.04.2019 | Event News

First dust conference in the Central Asian part of the earth’s dust belt

15.04.2019 | Event News

 
Latest News

Uncovering hidden protein structures

18.06.2019 | Life Sciences

Monitoring biodiversity with sound: how machines can enrich our knowledge

18.06.2019 | Life Sciences

Schizophrenia: Adolescence is the game-changer

18.06.2019 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>