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№ 94



  • V Международная конференция
    «Катализ для переработки возобновляемого сырья:
    топливо, энергия, химические продукты»
  • III Международная школа-конференция
    «Прикладные нанотехнологии и нанотоксикология»
  • За рубежом
  • Приглашения на конференции
  • Памяти Юрия Шаевича МАТРОСА

V Международная конференция «Катализ для переработки возобновляемого сырья: топливо, энергия, химические продукты»


III Международная школа-конференция «Прикладные нанотехнологии и нанотоксикология»


За рубежом

Japan scientists develop new catalyst capable of assisting three different key hydrogen reactions

Scientists from Kyushu University and Kumamoto University in Japan have developed a new catalyst capable of assisting three key reactions for using hydrogen in energy and industry. Inspired by three types of enzymes in nature, this research can help elucidate unknown relationships among catalysts, paving the way for efficient use of hydrogen gas as a next-generation energy source in the future.

One key for establishing hydrogen as a next-generation energy source is the development of catalysts that help use it efficiently. Catalysts play a role not only in splitting hydrogen molecules to generate electricity in fuel cells but also in putting hydrogen atoms together to form the fuel. Hydrogen also has many applications in the chemical industry, often being attached to molecules through the process of hydrogenation to modify their properties.

Nature has already developed its own set of biological catalysts—i.e., enzymes—capable of these same fundamental reactions. However, each of these three reactions requires a different type of enzyme, and these hydrogenase enzymes can be grouped by the metals they contain: an atom each of nickel and iron, two atoms of iron, or a single atom of iron.

Taking inspiration from nature, research teams led by Seiji Ogo from Kyushu University and Shinya Hayami from Kumamoto University now report in an open-access paper in the journal Science Advances (DOI: 10.1126/sciadv.aaz8181) that a single catalyst can perform all three roles.

The catalyst the scientists developed contains nickel and iron as the key metals. Depending on reaction conditions, hydrogen atoms will connect to the molecule in a slightly different way, leading to a twisting of the molecule that puts it in a configuration best suited for one of the three types of reactions.

While the enzymes in nature rely on different sets of metals to accomplish these reactions, the newly developed catalyst takes advantage of the molecular twist being enough to switch between structures similar to those of the three types of enzymes, thereby obtaining similar functions without changing the metals.

While the molecule may not be suitable for practical applications at present, it points toward the possibility of developing a single catalyst with multiple uses. More importantly, the better understanding of the catalytic processes afforded by this molecule can give crucial insight into natural enzymes and the development of future catalysts for realizing a hydrogen-powered society.

Green Car Congress


Ester dance moves substituents around arene rings

Palladium catalyst offers unusual route to high-value compounds



Rearrangement reactions are useful ways to make substituted aromatic molecules, but most of the methods that shift a substituent around an arene ring leave a functional group behind at the vacated carbon. A rare exception is the “halogen dance” reaction, in which a halogen atom hops to a neighboring carbon, while a hydrogen atom takes its original place.

Junichiro Yamaguchi and a team of chemical choreographers at Waseda University have now developed an analogous “ester dance” reaction, the first carbonyl group rearrangement of its kind (Sci. Adv. 2020, DOI: 10.1126/sciadv.aba7614). The reaction uses a palladium catalyst with a diphosphine-thiophene ligand and a base, and works on more than 30 different arenes, including naphthalenes (example shown) and pyridines. The discovery was a happy accident. “I’ve never seen such a reaction before,” says Yamaguchi.

The researchers think the palladium catalyst inserts itself into the ester before forming a palladium-arene intermediate. This subsequently reforms the ester at a thermodynamically favored position on an adjacent carbon.

They also teamed the ester dance with a decarbonylative coupling reaction, offering a one-pot route to a range of high-value molecules. Yamaguchi says the dance could be used to create ester and carboxylic acid intermediates for pharmaceuticals and agrochemicals.

Chemical & Engineering News


Same catalyst, different times, give different enantiomers

Reaction forms chiral amines in high selectivity



Different molecular enantiomers can have different chemistry, both in the body and in industrial processes. Controlling the yield of the right one is a time-consuming yet critical step in organic and pharmaceutical synthesis. Shu-Li You and coworkers at the Shanghai Institute of Organic Chemistry have found a surprising and simple shortcut: they can selectively make either enantiomer of some chiral amines just by varying the reaction times (Nat. Chem. 2020, DOI: 10.1038/s41557-020-0489-1). They used an iridium cyclooctadiene compound and a chiral olefin to create a chiral catalyst in solution, a common approach for asymmetric synthesis. After 6 min, S isomers form with 84–99% enantiomeric purity. If the researchers let the reaction go for 10 h, the R isomer forms with 74–99% enantiomeric purity (shown). The catalyst is highly selective for the S isomer and makes the compound quickly, You says. Over time, however, it decomposes and the more stable R isomer forms. The team discovered this while monitoring the reaction every 10 min. You says he was shocked by the results, as no one has reported this effect in asymmetric catalysis before. The team is now studying if the effect occurs with other reactions.

Chemical & Engineering News


Photocatalysis in flow functionalizes light hydrocarbons

Decatungstate plucks hydrogen atoms from C–H bonds in methane, ethane, propane, and isobutane


It typically takes some dramatic chemistry to turn light hydrocarbons like methane and propane into molecules that can be used as something other than fuel. Making them into one useful class of molecules, alkyl halides, requires using chlorine or bromine gas and sometimes temperatures in excess of 500 °C. Alkyl halides made this way are often turned into organometallic nucleophiles that form C–C bonds. Seeking a more direct way to use light hydrocarbons to make C–C bonds, chemists led by Eindhoven University of Technology’s Timothy Noël have now turned to the photocatalyst decatungstate (Science 2020, DOI: 10.1126/science.abb4688). In the presence of nearultraviolet light, decatungstate can pull a hydrogen atom from C–H bonds in methane, ethane, propane, or isobutane in a predictable manner. The resulting radical then reacts with a conjugated olefin to create a new C–C bond (example shown). Noël’s team performed the transformation in a microflow reactor under pressure, which can safely handle the combustible gases. The reactor forces the light hydrocarbons into the liquid phase, which makes them more likely to encounter decatungstate. Because the reaction conditions are mild and the photocatalyst is easy to prepare, the chemists say, the reaction is ideal for turning feedstock chemicals into more-interesting molecules.

Chemical & Engineering News

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Памяти Юрия Шаевича МАТРОСА


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