MSGID: 1:317/3 64ae2c6e   
   PID: hpt/lnx 1.9.0-cur 2019-01-08   
   TID: hpt/lnx 1.9.0-cur 2019-01-08   
    Highly efficient ruthenium-based catalysts with caffeine and   
   theophylline    
      
     Date:   
         July 11, 2023   
     Source:   
         University of Liege   
     Summary:   
         Researchers are developing highly efficient biosourced catalysts   
         based on caffeine and theophylline, two natural substances.   
      
      
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   FULL STORY   
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   A study by Lionel Delaude and Franc,ois Mazars, researchers from the   
   Laboratory of Catalysis at the University of Lie`ge (Belgium), has shown   
   that caffeine and theophylline can be used to 'green' catalysts based on   
   ruthenium. This chemical element belongs to the transition metals. The   
   results of this study have been published in the scientific journal   
   Organometallics and will remainin open access for six months.   
      
   Catalysts are ubiquitous in chemical processes because they enable   
   reactions to be carried out faster and more selectively under milder   
   experimental conditions. They are generally obtained from non-renewable   
   raw materials, often derived from petrochemicals and metallurgy. In line   
   with the twelve principles of "green chemistry," chemists are now seeking   
   to reduce the carbon footprint of their processes as much as possible. In   
   this context, the team from the Laboratory of Organometallic Chemistry   
   and Homogeneous Catalysis at the University of Lie`ge has developed   
   biobased catalysts derived from caffeine and theophylline, two natural   
   substances from the xanthine family found in large quantities in coffee   
   beans, tea leaves, and cocoa beans. The whole process of adding value   
   to these compounds is environmentally friendly, since their extraction   
   and separation from renewable plant sources requires only water and   
   supercritical CO2 ,"explains Lionel Delaude, professor of chemistry and   
   director of the laboratory. What's more, they are under-exploited and   
   available at low cost.   
      
   Slight modifications to the chemical structure of xanthines can be used   
   to synthesize N-heterocyclic carbene precursors, which form the basis of   
   many catalysts in the 21st century. The work of Lionel Delaude and his   
   doctoral student Franc,ois Mazars has shown that the combination of a   
   para-cymene ligand derived from a-phellandrene (an essential oil found   
   in many plants, including dill and eucalyptus) and an N-heterocyclic   
   carbene ligand derived from caffeine or theophylline with ruthenium   
   (a low-toxicity metal from the iron family) leads to the formation of   
   highly effective catalysts for promoting three major types of organic   
   reaction, namely, the transfer hydrogenation of unsaturated substrates   
   with isopropanol, the oxidation of alkenes with sodium periodate,   
   and the synthesis of vinyl esters from 1-hexyne and benzoic acid. This   
   discovery contributes to developing more sustainable and environmentally   
   friendly organometallic chemistry. Moreover, it opens the door to other   
   catalytic applications using caffeine and theophylline to generate bio   
   sourced N-heterocyclic carbenes.   
      
   This publication in Organometallicshas been singled out by the editors   
   of the American Chemical Society to be highlighted on the day of its   
   publication (28 May 2023) and to remain in open access for six months   
   as part of the ACS Editors' Choice programme. It has also been selected   
   to appear on the cover of an issue of the journal (July 10 2023).   
      
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   Source: Materials provided by University_of_Liege. Note: Content may be   
   edited for style and length.   
      
      
   ==========================================================================   
   Journal Reference:   
      1. Franc,ois Mazars, Lionel Delaude. "Greening" Ruthenium-Arene   
      Catalyst   
         Precursors with N-Heterocyclic Carbene Ligands Derived from   
         Caffeine and Theophylline. Organometallics, 2023; 42 (13): 1589 DOI:   
         10.1021/ acs.organomet.3c00166   
   ==========================================================================   
      
   Link to news story:   
   https://www.sciencedaily.com/releases/2023/07/230711130745.htm   
      
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