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 ==========================================================================
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).

* RELATED_TOPICS
o Plants_&_Animals
# Food # Agriculture_and_Food # Biology # Botany
o Matter_&_Energy
# Chemistry # Organic_Chemistry # Inorganic_Chemistry
# Biochemistry
* RELATED_TERMS
o Caffeine o Natural_gas o Botulinum_toxin_(cosmetic_treatment)
o Conservation_ethic o Plastic o Redox o Science o Hydroponics

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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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