A study by Lionel Delaude and François Mazars, researchers from the Laboratory of Catalysis at the University of Liège (Belgium), showed that caffeine and theophylline can be used in “green” catalysts based on ruthenium. This chemical element belongs to the transition metals. The results of this study were published in Organometallics.
Catalysts are ubiquitous in chemical processes because they enable reactions to occur faster and more selectively under milder experimental conditions. It is usually obtained from non-renewable raw materials, often from petrochemicals and metallurgy. In line with the twelve principles of “green chemistry”, today’s chemists seek 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 Liège has developed biobased catalysts derived from caffeine and theophylline, two natural substances from the xanthine family found in many coffee beans, tea leaves, and cocoa. beans.
“The whole process of adding value to these compounds is environmentally friendly, because their extraction and separation from renewable plant sources only requires water and supercritical CO.2 “explains Lionel Delaude, professor of chemistry and director of the laboratory. “What’s more, they are not exploited and can be used at low cost.”
Small changes in the chemical structure of xanthine can be used to synthesize N-heterocyclic carbene precursors, which form the basis of many catalysts of the 21st century. The work of Lionel Delaude and his doctoral student François Mazars showed 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) lead to the formation of highly effective catalysts for the development of three major types of organic reactions; 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 contributed to the development of a more sustainable and friendly organometallic chemistry. Furthermore, it opens the door to other catalytic applications using caffeine and theophylline to generate bio sourced N-heterocyclic carbenes.
François Mazars et al, “Greening” Ruthenium–Arene Catalyst Precursors with N-Heterocyclic Carbene Ligands Derived from Caffeine and Theophylline, Organometallics (2023). DOI: 10.1021/acs.organomet.3c00166
Awarded by the University of Liege
Citation: Do you take ruthenium in your tea or coffee? (2023, July 13) retrieved 13 July 2023 from https://phys.org/news/2023-07-ruthenium-tea-coffee.html
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