such as "Introduction", "Conclusion"..etc
Researchers at the University of California, Riverside have
successfully created in the laboratory a class of carbenes, highly
reactive molecules, used to make catalysts -- substances that
facilitate chemical reactions. Until now, chemists believed these
carbenes, called "abnormal N-heterocyclic carbenes" or aNHCs, were
impossible to make.
Carbenes are made up of unusual carbon atoms and are usually
unstable in nature. They attach themselves to metals to form
metal-carbene complexes that serve as efficient catalysts used widely
in the pharmaceutical industry.
The metal-carbene complexes are formed in two ways: (a) the complex
is created in one step, without first preparing carbene independently,
and (b) a metal and an independent carbene are brought together to make
Most often the metal used in a metal-carbene complex is rhodium,
gold, platinum or palladium -- all of which are very expensive and, in
some cases, even toxic. To bring down the cost of catalysts, when
possible, carbenes are used independently (without metals) in many
Until now, aNHCs have been used as only metal-carbene complexes,
never independently. Chemists had assumed that aNHCs cannot exist
freely, which made them impossible to make.
Now UC Riverside's Guy Bertrand, a distinguished professor of
chemistry, and colleagues have challenged that assumption by
successfully creating aNHCs that are metal-free and can be used to make
any desired complex.
"Many chemical species are believed to be unstable because they do
not obey the rules we learned at school, and consequently nobody tries
to make them," said Bertrand, who led the research project. "The role
of scientists, however, is to challenge former hypotheses. That is just
what we did in the case of the aNHCs, and we were successful.
"The aNHCs are stable at room temperature both in the solid state
and in solution, which means their application as metal-free catalysts
is extremely wide, greatly benefiting industry by making possible
scores of new chemical reactions."
Results of the study appear in the Oct. 23 issue of Science.
"This study, reporting the synthesis and characterization of an
entirely different class of metal-free NHCs, could open new horizons
and have a huge impact on the field of catalysis," said John Schwab,
who oversees organic synthesis grants at the National Institutes of
Health's National Institute of General Medical Sciences. "The potential
applications to drug discovery and manufacture are exciting, since
catalytic processes can help keep costs in check and be environmentally
friendly, to boot."
Bertrand is interested in making aNHCs commercially available. "We
hope many chemists in the world will use these carbenes and find some
new applications," he said.
The UCR Office of Technology Commercialization has filed a patent
application on the technology and is currently seeking partners in
industry interested in developing the technology commercially.
Bertrand was joined in the research by Eugenia Aldeco-Perez, Amos J.
Rosenthal, and Bruno Donnadieu of UCR; and Gernot Frenking and Pattiyil
Parameswaran of Phillips-Universitat Marburg, Germany.
The research project was funded by the National Institutes of
Health. The National Council for Science and Technology (CONACYT),
Mexico, provided Aldeco-Perez, the first author of the research paper,
with financial support.
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