Adding olefin enables efficient solvent-free cross-coupling reactions, leading to environmentally friendly syntheses of a wide range of organic materials.
A cross coupling reaction is typically performed in an organic solvent and leads to the production of a large amount of solvent waste, which is often harmful to the environment.
Top: Electron microscopic images of palladium nanoparticles in the reaction mixtures. After 99 minutes of the reaction, the palladium catalyst was found aggregated and deactivated itself (left) while the addition of olefin kept the catalyst dispersed (right). Bottom: Schematic illustration showing the function of olefin as a dispersant.
Credit: Kubota K. et al., Nature Communications, Jan. 10, 2019
Usage Restrictions: This image is copyrighted and can be used for reporting this press release if properly credited.
A new strategy developed by Hokkaido University researchers in Japan opens the door for more environmentally friendly solvent-free solid-state cross coupling processes using mechanochemistry. It also has many potential applications, including the development of organic materials found in solar cells and light-emitting diodes.
Cross-coupling reactions proceed efficiently in the presence of a metal catalyst to form a wide range of organic molecules with novel properties.
In particular, the Nobel-prize-winning palladium-catalysed cross-coupling reactions have long been used in the synthesis of natural products, in medicinal chemistry, and in polymer and materials science.
To reduce environmental waste, researchers have been looking at methods to enable efficient organic syntheses that use less or no solvent. In this context, "solid-state organic transformations" have received considerable research attention, but improving the efficiency of cross-coupling reactions in solid media remains a challenge.
In a study published in Nature Communications, Hokkaido University organic chemists Koji Kubota, Hajime Ito and their colleagues developed a new strategy for solid-state palladium-catalysed cross-coupling reactions using mechanochemistry that enables efficient solvent-free synthesis of organic materials.
Two solid organic materials were placed inside a ball milling jar that contains a stainless steel grinding ball. A palladium-based catalyst was also added. The jar undergoes a shaking process that causes the ball to grind the solid compounds, initiating a cross-coupling reaction.
They found that the palladium-based catalyst tended to aggregate during the reaction, which may lead to catalyst deactivation. But, when olefin such as 1,5-cyclooctadiene was added to the mixture, it acted as a dispersant for the palladium-based catalyst, facilitating a more efficient solid-state cross-coupling reaction. When olefin was added, the conversion rate of the reaction went up from less than 30% to 99%.
"Our protocol should be particularly useful for reducing the amount of organic solvent used in industry that is harmful to the environment. It will also make the production process less costly," said Hajime Ito.
"The new method could be applied to, for example, the production of triarylamines that can be found in a wide range of organic materials including solar cells and light-emitting diodes."
Tyler Tannert | EurekAlert!
Monitoring biodiversity with sound: how machines can enrich our knowledge
18.06.2019 | Georg-August-Universität Göttingen
Uncovering hidden protein structures
18.06.2019 | Universität Konstanz
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...
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...
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...
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....
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...
29.04.2019 | Event News
17.04.2019 | Event News
15.04.2019 | Event News
18.06.2019 | Life Sciences
18.06.2019 | Life Sciences
18.06.2019 | Life Sciences