Chemistry Articles and News

In Crystallo Snapshots of Rh2‑Catalyzed C−H Amination

In Crystallo Snapshots of Rh2‑Catalyzed C−H Amination

January 22, 2021    
Chemist    

While X-ray crystallography routinely provides structural characterization of kinetically stable pre-catalysts and intermediates, elucidation of the structures of transient reactive intermediates, which are intimately engaged in bond-breaking and -making during catalysis, is generally not possible. Here, we demonstrate in crystallo synthesis of Rh2 nitrenoids that participate in catalytic C–H amination, and we characterize these transient intermediates as triplet adducts of Rh2.

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Mechanochemical Cross-Coupling Reactions

Mechanochemical Cross-Coupling Reactions

January 22, 2021    
Chemist    

Mechanochemical synthesis avoids the use of potentially harmful organic solvents, thus providing an attractive and environmentally friendly alternative to solution-based synthesis. Mechanochemical cross-coupling reactions enable cleaner and more sustainable access to a wide range of valuable synthetic targets in organic materials and modern drug discovery.

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Download Periodic Table 2021 PRO - Chemistry v0.2.112

Download Periodic Table 2021 PRO – Chemistry v0.2.112

January 21, 2021    
Chemist    

Periodic Table 2021 PRO – Chemistry v0.2.112 for android Full Cracked. The chemistry falls into to number of the most important sciences and is one of the main school objects. Its studying begins with the Periodic Table. Interactive approach to a training material is more effective than classical. As in it technologies which became the family for the modern pupils are used. Differences PRO version of FREE: • More interactive tables • Continuous addition of new application information elements • More information about the additional elements • Conductivity • Electric type • Magnetic type • Bulk magnetic susceptibility • Specific magnetic susceptibility • Temperature Superconductivity • Color of the item • Density • Refractive Index • Coefficient of thermal conductivity • Electronegativity • Valence • Radioactivity • Half life • Molar volume What’s New in Periodic Table 2021 PRO – Chemistry v0.2.112 Meet the updated tables! Detailed data on solubility

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Carbon-based catalysts for Fischer–Tropsch synthesis

Carbon-based catalysts for Fischer–Tropsch synthesis

January 8, 2021    
Chemist    

Fischer–Tropsch synthesis (FTS) is an essential approach to convert coal, biomass, and shale gas into fuels and chemicals, such as lower olefins, gasoline, diesel, and so on. In recent years, there has been increasing motivation to deploy FTS at commercial scales which has been boosting the discovery of high performance catalysts. In particular, the importance of support in modulating the activity of metals has been recognized and carbonaceous materials have attracted attention as supports for FTS. In this review, we summarised the substantial progress in the preparation of carbon-based catalysts for FTS by applying activated carbon (AC), carbon nanotubes (CNTs), carbon nanofibers (CNFs), carbon spheres (CSs), and metal–organic frameworks (MOFs) derived carbonaceous materials as supports. A general assessment of carbon-based catalysts for FTS, concerning the support and metal properties, activity and products selectivity, and their interactions is systematically discussed. Finally, current challenges and future trends in the development of carbon-based

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Mechanochemistry for ammonia synthesis under mild conditions

Mechanochemistry for ammonia synthesis under mild conditions

December 25, 2020    
Chemist    

Ammonia, one of the most important synthetic feedstocks, is mainly produced by the Haber–Bosch process at 400–500 °C and above 100 bar. The process cannot be performed under ambient conditions for kinetic reasons. Here, we demonstrate that ammonia can be synthesized at 45 °C and 1 bar via a mechanochemical method using an iron-based catalyst. With this process the ammonia final concentration reached 82.5 vol%, which is higher than state-of-the-art ammonia synthesis under high temperature and pressure (25 vol%, 450 °C, 200 bar).

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Temporary or removable directing groups enable activation of unstrained C–C bonds

Temporary or removable directing groups enable activation of unstrained C–C bonds

September 25, 2020    
Chemist    

Carbon–carbon (C–C) bonds make up the skeletons of most organic molecules. The selective manipulation of C–C bonds offers a direct approach to editing molecular scaffolds but remains challenging. The kinetic inertness of C–C bonds can be overcome with transition-metal catalysis, which, nevertheless, relies on a substrate being highly strained or bearing a permanent directing group (DG). The driving force for C–C activation in these cases is strain relief and the formation of a stable metallocycle, respectively. Over the past two decades, a strategy has emerged that uses temporary or removable DGs to effect C–C activation of more common and less strained compounds.

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