13-Feb-2019 - Hokkaido University

Boosting solid state chemical reactions

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. 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, 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."

Facts, background information, dossiers

More about Hokkaido University

  • News

    A new tool to create chemical complexity from fatty acids

    Hokkaido University WPI-ICReDD researchers developed a modular catalyst that can accurately modify fatty acid derivatives in a hitherto inaccessible position. This enables the efficient production of valuable compounds from a renewable bioresource, whereas before we had to either rely on pe ... more

    Repeated interferon stimulation creates innate immune memory

    The innate immune system may be able to be trained to react to viral infections more efficiently by repeated exposure to anti-viral signaling molecules. Mammalian cells seem to be able to memorize anti-viral stimulation at the level of DNA-packaging molecules, enabling faster and greater ac ... more

    New record set for carbon-carbon single bond length

    A stable organic compound has been synthesized with a record length for the bond between its carbon atoms, exceeding the assumed limit. Hokkaido University researchers have synthesized an organic compound with a longer bond between carbon atoms than ever before - exceeding the assumed limit ... more

q&more – the networking platform for quality excellence in lab and process

The q&more concept is to increase the visibility of recent research and innovative solutions, and support the exchange of knowledge. In the broad spectrum of subjects covered, the focus is on achieving maximum quality in highly innovative sectors. As a modern knowledge platform, q&more offers market participants one-of-a-kind networking opportunities. Cutting-edge research is presented by authors of international repute. Attractively presented in a high-quality context, and published in German and English, the original articles introduce new concepts and highlight unconventional solution strategies.

> more about q&more

q&more is supported by: